SCONS(1)

NAME
scons - a software construction tool

SYNOPSIS

scons [options...] [name=val...] [targets...]

DESCRIPTION

SCons is an extensible open source build system that orchestrates the construction of software (and other tangible products such as documentation files) by determining which component pieces must be built or rebuilt and invoking the necessary commands to build them. SCons offers many features to improve developer productivity such as parallel builds, caching of build artifacts, automatic dependency scanning, and a database of information about previous builds so details do not have to be recalculated each run.

scons requires Python 3.6 or later to run; there should be no other dependencies or requirements, unless the experimental Ninja tool is used (requires the ninja package).

Changed in version 4.3.0: support for Python 3.5 is removed. The CPython project retired 3.5 in Sept 2020: https://peps.python.org/pep-0478.

Changed in version 4.8.0: support for Python 3.6 is deprecated and will be removed in a future SCons release. The CPython project retired 3.6 in Sept 2021: https://peps.python.org/pep-0494.

You set up an SCons build by writing a script that describes things to build (targets), and, if necessary, the rules to build those files (actions). SCons comes with a collection of Builder methods which supply premade Actions for building many common software components such as executable programs, object files and libraries, so that for many software projects, only the targets and input files (sources) need be specified in a call to a builder.

SCons operates at a level of abstraction above that of pure filenames. For example if you specify a shared library target named "foo", SCons keeps track of the actual operating system dependent filename (such as libfoo.so on a GNU/Linux system and foo.dll on Windows), and gives you a handle to refer to that target in other steps, so you don't have to use system-specific strings yourself. SCons can also scan automatically for dependency information, such as header files included by source code files (for example, #include preprocessor directives in C or C++ files), so these implicit dependencies do not have to be specified manually. SCons supports the ability to define new scanners to support additional input file types.

Information about files involved in the build, including a cryptographic hash of the contents of source files, is cached for later reuse. By default this hash (the content signature) is used to decide if a file has changed since the last build, although other algorithms can be used by selecting an appropriate Decider function. Implicit dependency files are also part of out-of-date computation. The scanned implicit dependency information can optionally be cached and used to speed up future builds. A hash of each executed build action (the build signature) is also cached, so that changes to build instructions (changing flags, etc.) or to the build tools themselves (e.g. a compiler upgrade) can also trigger a rebuild.

SCons supports separated source and build directories (also called "out-of-tree builds") through the definition of variant directories Using a separated build directory helps keep the source directory clean of artifacts when doing searches, allows setting up differing builds ("variants") without conflicts, and allows resetting the build by just removing the build directory (note that SCons does have a "clean" mode as well). See the VariantDir description for more details.

When invoked, scons looks for a file describing the build configuration in the current directory and reads that in. The file is by default named SConstruct, although some variants of that, or a developer-chosen name, are also accepted (see the section called “SConscript Files”). If found, the currrent directory is set as the project top directory. Certain command-line options specify alternate places to look for SConstruct (see -C, -D, -u and -U), which will set the project top directory to the path found. A path to the build configuration can also be specified with the -f option, which leaves the current directory as the project top directory.

The build configuration may be split into multiple files: the SConstruct file can specify additional configuration files by calling the SConscript function, and any file thus invoked may include further files in the same way. By convention, these subsidiary files are named SConscript, although any name may be used. As a result of this naming convention, the term SConscript files is used to refer generically to the complete set of configuration files for a project (including the SConstruct file), regardless of the actual file names or number of such files. A hierarchical build is not recursive - all of the SConscript files are processed in a single pass so that scons has a picture of the complete dependency tree when it begins considering what needs building. Each SConscript file is processed in a separate context so settings made in one script do not leak into another; information can however be shared explicitly between scripts.

Before reading the SConscript files, scons looks for a site directory - a directory named site_scons is searched for in various system directories and in the project top directory, or if the --site-dir option is given, checks only for that directory. Found site directories are prepended to the Python module search path (sys.path), thus allowing modules in such directories to be imported in the normal Python way in SConscript files. For each found site directory, (1) if it contains a file site_init.py that file is evaluated, and (2) if it contains a directory site_tools the path to that directory is prepended to the default toolpath. See the --site-dir and --no-site-dir options for details on default paths and controlling the site directories.

SConscript files are written in the Python programming language. For many tasks, the simple syntax can be understood from examples, so it is normally not necessary to be a Python programmer to use SCons effectively. SConscript files are executed in a context that makes the facilities described in this manual page directly available (that is, no need to import). Standard Python scripting capabilities such as flow control, data manipulation, and imported Python modules are available to use in more complicated build configurations. Other Python files can be made a part of the build system, but they do not automatically have the SCons context and need to import it if they need access (described later).

SCons reads and executes all of the included SConscript files before it begins building any targets. Progress messages show this behavior (the state change lines - those beginning with the scons: tag - may be suppressed using the -Q option):

    $ scons foo.out
    scons: Reading SConscript files ...
    scons: done reading SConscript files.
    scons: Building targets  ...
    cp foo.in foo.out
    scons: done building targets.
    $

To assure reproducible builds, SCons uses a restricted execution environment for running external commands used to build targets, rather then propagating the full environment in effect at the time scons was called. This helps avoid problems like picking up accidental or malicious settings, temporary debug values that are no longer needed, or a developer having different settings than another (or than the CI pipeline). Environment variables needed for the proper operation of such commands must be set in the execution environment explicitly, either by assigning the desired values, or by picking those values individually or collectively out of environment variables exposed by the Python os.environ dictionary (as external program inputs they should be validate before use). The execution environment for a given construction environment is its $ENV value. A small number of environment variables are picked up automatically by scons itself (see the section called “ENVIRONMENT”).

In particular, if a compiler or other external command needed to build a target file is not in scons' idea of a standard system location, it will not be found at runtime unless you explicitly add the location into the execution environment's PATH element. This is a particular consideration on Windows platforms, where it is common for a command to install into an app-specific location and depend on setting PATH in order for them to be found, which does not automatically work for SCons.

One example approach is to extract the entire PATH environment variable and set that into the execution environment:

    import os
    env = Environment(ENV={'PATH': os.environ['PATH']})

Similarly, if the commands use specific external environment variables that scons does not recognize, they can be propagated into the execution environment:

    import os
    env = Environment(
        ENV={
            'PATH': os.environ['PATH'],
            'MODULEPATH': os.environ['MODULEPATH'],
            'PKG_CONFIG_PATH': os.environ['PKG_CONFIG_PATH'],
        }
    )

Or you can explicitly propagate the invoking user's complete external environment:

    import os
    env = Environment(ENV=os.environ.copy())

This comes at the expense of making your build dependent on the user's environment being set correctly, but it may be more convenient for some configurations. It should not cause problems if done in a build setup which tightly controls how the environment is set up before invoking scons, as in many continuous integration setups.

    Note

    The above fragments are intended to illustrate a concept. It is normally not a good idea to wipe out the entire default value of the execution environment (env["ENV"]), as it may carry important information for the execution of build commands.

scons is normally executed in a top-level directory containing an SConstruct file (the project top directory). When scons is invoked, the command line (including the contents of the SCONSFLAGS environment variable, if set) is processed. Command-line options (see the section called “OPTIONS”) are consumed. Any variable argument assignments are collected, and remaining arguments are taken as targets to build.

Values of variables to be passed to the SConscript files may be specified on the command line:

    scons debug=1

These variables are available through the ARGUMENTS dictionary, and can be used in the SConscript files to modify the build in any way:

    if ARGUMENTS.get("debug", ""):
        env = Environment(CCFLAGS="-g")
    else:
        env = Environment()

The command-line variable arguments are also available in the ARGLIST list, indexed by their order on the command line. This allows you to process them in order rather than by name, if necessary. Each ARGLIST entry is a tuple consisting of the name and the value.

See the section called “Command-Line Construction Variables” for more information.

scons can maintain a cache of target (derived) files that can be shared between multiple builds. When derived-file caching is enabled in an SConscript file, any target files built by scons will be copied to the cache. If an up-to-date target file is found in the cache, it will be retrieved from the cache instead of being rebuilt locally. Caching behavior may be disabled and controlled in other ways by the --cache-force, --cache-disable, --cache-readonly, and --cache-show command-line options. The --random option is useful to prevent multiple builds from trying to update the cache simultaneously.

By default, scons searches for known programming tools on various systems and initializes itself based on what is found. On Windows systems which identify as win32, scons searches in order for the Microsoft Visual C++ tools, the MinGW tool chain, the Intel compiler tools, and the PharLap ETS compiler. On Windows system which identify as cygwin (that is, if scons is invoked from a cygwin shell), the order changes to prefer the GCC toolchain over the MSVC tools. On OS/2 systems, scons searches in order for the OS/2 compiler, the GCC tool chain, and the Microsoft Visual C++ tools, On SGI IRIX, IBM AIX, Hewlett Packard HP-UX, and Oracle Solaris systems, scons searches for the native compiler tools (MIPSpro, Visual Age, aCC, and Forte tools respectively) and the GCC tool chain. On all other platforms, including POSIX (Linux and UNIX) and macOS platforms, scons searches in order for the GCC tool chain, and the Intel compiler tools. The defaul tool selection can be pre-empted through the use of the tools argument to construction environment creation methods, explcitly calling the Tool loader, the through the setting of various setting of construction variables.

  Target Selection

SCons acts on the selected targets, whether the requested operation is build, no-exec or clean. Targets are selected as follows:

    1. Targets specified on the command line. These may be files, directories, or phony targets defined using the Alias function. Directory targets are scanned by scons for any targets that may be found with a destination in or under that directory. The targets listed on the command line are made available in the COMMAND_LINE_TARGETS list.

    2. If no targets are specified on the command line, scons will select those targets specified in the SConscript files via calls to the Default function. These are known as the default targets, and are made available in the DEFAULT_TARGETS list.

    3. If no targets are selected by the previous steps, scons selects the current directory for scanning, unless command-line options which affect the directory for target scanning are present (-C, -D, -u, -U). Since targets thus selected were not the result of user instructions, this target list is not made available for direct inspection; use the --debug=explain option if they need to be examined.

    4. scons always adds to the selected targets any intermediate targets which are necessary to build the specified ones. For example, if constructing a shared library or dll from C source files, scons will also build the object files which will make up the library.

To ignore the default targets specified through calls to Default and instead build all target files in or below the current directory specify the current directory (.) as a command-line target:

    scons .

To build all target files, including any files outside of the current directory, supply a command-line target of the root directory (on POSIX systems):

    scons /

or the path name(s) of the volume(s) in which all the targets should be built (on Windows systems):

    scons C:\ D:\

A subset of a hierarchical tree may be built by remaining at the project top directory and specifying the subdirectory as the target to build:

    scons src/subdir

or by changing directory and invoking scons with the -u option, which traverses up the directory hierarchy until it finds the SConstruct file, and then builds targets relatively to the current subdirectory (see also the related -D and -U options):

    cd src/subdir
    scons -u .

In all cases, more files may be built than are requested, as scons needs to make sure any dependent files are built.

Specifying "cleanup" targets in SConscript files is usually not necessary. The -c flag removes all selected targets:

    scons -c .

to remove all target files in or under the current directory, or:

    scons -c build export

to remove target files under build and export.

Additional files or directories to remove can be specified using the Clean function in the SConscript files. Conversely, targets that would normally be removed by the -c invocation can be retained by calling the NoClean function with those targets.

scons supports building multiple targets in parallel via a -j option that takes, as its argument, the number of simultaneous tasks that may be spawned:

    scons -j 4

builds four targets in parallel, for example.

OPTIONS

In general, scons supports the same command-line options as GNU Make and many of those supported by cons.

-b
    Ignored for compatibility with non-GNU versions of Make

-c, --clean, --remove
    Set clean mode. Clean up by removing the selected targets, well as any files or directories associated with a selected target through calls to the Clean function. Will not remove any targets which are marked for preservation through calls to the NoClean function.

    While clean mode removes targets rather than building them, work which is done directly in Python code in SConscript files will still be carried out. If it is important to avoid some such work from taking place in clean mode, it should be protected. An SConscript file can determine which mode is active by querying GetOption, as in the call if GetOption("clean"):

--cache-debug=file
    Write debug information about derived-file caching to the specified file. If file is a hyphen (-), the debug information is printed to the standard output. The printed messages describe what signature-file names are being looked for in, retrieved from, or written to the derived-file cache specified by CacheDir.

--cache-disable, --no-cache
    Disable derived-file caching. scons will neither retrieve files from the cache nor copy files to the cache. This option can be used to temporarily disable the cache without modifying the build scripts.

--cache-force, --cache-populate
    When using CacheDir, populate a derived-file cache by copying any already-existing, up-to-date derived files to the cache, in addition to files built by this invocation. This is useful to populate a new cache with all the current derived files, or to add to the cache any derived files recently built with caching disabled via the --cache-disable option.

--cache-readonly
    Use the derived-file cache, if enabled, to retrieve files, but do not not update the cache with any files actually built during this invocation.

--cache-show
    When using a derived-file cache show the command that would have been executed to build the file (or the corresponding *COMSTR contents if set) even if the file is retrieved from cache. Without this option, scons shows a cache retrieval message if the file is fetched from cache. This allows producing consistent output for build logs, regardless of whether a target file was rebuilt or retrieved from the cache.

--config=mode
    Control how the Configure call should use or generate the results of configuration tests. mode should be one of the following choices:

    auto
        SCons will use its normal dependency mechanisms to decide if a test must be rebuilt or not. This saves time by not running the same configuration tests every time you invoke scons, but will overlook changes in system header files or external commands (such as compilers) if you don't specify those dependecies explicitly. This is the default behavior.

    force
        If this mode is specified, all configuration tests will be re-run regardless of whether the cached results are out of date. This can be used to explicitly force the configuration tests to be updated in response to an otherwise unconfigured change in a system header file or compiler.

    cache
        If this mode is specified, no configuration tests will be rerun and all results will be taken from cache. scons will report an error if --config=cache is specified and a necessary test does not have any results in the cache.

-C directory, --directory=directory
    Run as if scons was started in directory instead of the current working directory. That is, change directory before searching for the SConstruct, Sconstruct, sconstruct, SConstruct.py, Sconstruct.py or sconstruct.py file or doing anything else. When multiple -C options are given, each subsequent non-absolute -C directory is interpreted relative to the preceding one. See also options -u, -U and -D to change the SConstruct search behavior when this option is used.

-D
    Works exactly the same way as the -u option except for the way default targets are handled. When this option is used and no targets are specified on the command line, all default targets are built, whether or not they are below the current directory.

--debug=type[,type...]
    Debug the build process. type specifies the kind of debugging info to emit. Multiple types may be specified, separated by commas. The following types are recognized:

    action-timestamps
        Prints additional time profiling information. For each command, shows the absolute start and end times. This may be useful in debugging parallel builds. Implies the --debug=time option.

        New in version 3.1.

    count
        Print how many objects are created of the various classes used internally by SCons before and after reading the SConscript files and before and after building targets. This is not supported when SCons is executed with the Python -O (optimized) option or when the SCons modules have been compiled with optimization (that is, when executing from *.pyo files).

    duplicate
        Print a line for each unlink/relink (or copy) of a file in a variant directory from its source file. Includes debugging info for unlinking stale variant directory files, as well as unlinking old targets before building them.

    explain
        Print an explanation of why scons is deciding to (re-)build the targets it selects for building.

    findlibs
        Instruct the scanner that searches for libraries to print a message about each potential library name it is searching for, and about the actual libraries it finds.

    includes
        Print the include tree after each top-level target is built. This is generally used to find out what files are included by the sources of a given derived file:

            $ scons --debug=includes foo.o

    json
        Write info to a JSON file for any of the following debug options if they are enabled: memory, count, time, action-timestamps

        The default output file is scons_stats.json

        The file name/path can be modified by using DebugOptions for example DebugOptions(json='path/to/file.json')

            $ scons --debug=memory,json foo.o

    memoizer
        Prints a summary of hits and misses using the Memoizer, an internal subsystem that counts how often SCons uses cached values in memory instead of recomputing them each time they're needed.

    memory
        Prints how much memory SCons uses before and after reading the SConscript files and before and after building targets.

    objects
        Prints a list of the various objects of the various classes used internally by SCons.

    pdb
        Run scons under control of the pdb Python debugger.

            $ scons --debug=pdb
            > /usr/lib/python3.11/site-packages/SCons/Script/Main.py(869)_main()
            -> options = parser.values
            (Pdb)

            Note
            pdb will stop at the beginning of the scons main routine on startup. The search path (sys.path) at that point will include the location of the running scons, but not of the project itself. If you need to set breakpoints in your project files, you will either need to add to the path, or use absolute pathnames when referring to project files. A .pdbrc file in the project root can be used to add the current directory to the search path to avoid having to enter it by hand, along these lines:

                sys.path.append('.')

            Due to the implementation of the pdb module, the break, tbreak and clear commands only understand references to filenames which have a .py extension. (although the suffix itself can be omitted), except if you use an absolute path. As a special exception to that rule, the names SConstruct and SConscript are recognized without needing the .py extension.

            Changed in version 4.6.0: The names SConstruct and SConscript are now recognized without requiring .py suffix.

            Changed in version 4.8.0: The name SCsub is now recognized without requiring .py suffix.

    prepare
        Print a line each time any target (internal or external) is prepared for building. scons prints this for each target it considers, even if that target is up to date (see also --debug=explain). This can help debug problems with targets that aren't being built; it shows whether scons is at least considering them or not.

    presub
        Print the raw command line used to build each target before the construction environment variables are substituted. Also shows which targets are being built by this command. Output looks something like this:

            $ scons --debug=presub
            Building myprog.o with action(s):
              $SHCC $SHCFLAGS $SHCCFLAGS $CPPFLAGS $_CPPINCFLAGS -c -o $TARGET $SOURCES
            ...

    stacktrace
        Prints an internal Python stack trace when encountering an otherwise unexplained error.

    time
        Prints various time profiling information:

            • The time spent executing each individual build command

            • The total build time (time SCons ran from beginning to end)

            • The total time spent reading and executing SConscript files

            • The total time SCons itself spent running (that is, not counting reading and executing SConscript files)

            • The total time spent executing all build commands

            • The elapsed wall-clock time spent executing those build commands

            • The time spent processing each file passed to the SConscript function

        (When scons is executed without the -j option, the elapsed wall-clock time will typically be slightly longer than the total time spent executing all the build commands, due to the SCons processing that takes place in between executing each command. When scons is executed with the -j option, and your build configuration allows good parallelization, the elapsed wall-clock time should be significantly smaller than the total time spent executing all the build commands, since multiple build commands and intervening SCons processing should take place in parallel.)

    sconscript
        Enables output indicating entering and exiting each SConscript file.

--diskcheck=type
    Enable specific checks for whether or not there is a file on disk where the SCons configuration expects a directory (or vice versa) when searching for source and include files. type can be an available diskcheck type or the special tokens all or none. A comma-separated string can be used to select multiple checks. The default setting is all.

    Current available checks are:

    match
        to check that files and directories on disk match SCons' expected configuration.

    Disabling some or all of these checks can provide a performance boost for large configurations, or when the configuration will check for files and/or directories across networked or shared file systems, at the slight increased risk of an incorrect build or of not handling errors gracefully.

--duplicate=ORDER
    There are three ways to duplicate files in a build tree: hard links, soft (symbolic) links and copies. The default policy is to prefer hard links to soft links to copies. You can specify a different policy with this option. ORDER must be one of hard-soft-copy (the default), soft-hard-copy, hard-copy, soft-copy or copy. SCons will attempt to duplicate files using the mechanisms in the specified order.

--enable-virtualenv
    Import virtualenv-related variables to SCons.

--experimental=feature
    Enable experimental features and/or tools. feature can be an available feature name or the special tokens all or none. A comma-separated string can be used to select multiple features. The default setting is none.

    Current available features are: ninja (New in version 4.2), legacy_sched (New in version 4.6.0).

        Caution
        No Support offered for any features or tools enabled by this flag.

    New in version 4.2 (experimental).

-f file, --file=file, --makefile=file, --sconstruct=file
    Use file as the initial SConscript file. Multiple -f options may be specified, in which case scons will read all of the specified files.

-h, --help
    Print a local help message for this project, if one is defined in the SConscript files (see the Help function), plus a line that refers to the standard SCons help message. If no local help message is defined, prints the standard SCons help message (as for the -H option) plus help for any local options defined through AddOption. Exits after displaying the appropriate message.

    Note that use of this option requires SCons to process the SConscript files, so syntax errors may cause the help message not to be displayed.

--hash-chunksize=KILOBYTES
    Set the block size used when computing content signatures to KILOBYTES. This value determines the size of the chunks which are read in at once when computing signature hashes. Files below that size are fully stored in memory before performing the signature computation while bigger files are read in block-by-block. A huge block-size leads to high memory consumption while a very small block-size slows down the build considerably.

    The default value is to use a chunk size of 64 kilobytes, which should be appropriate for most uses.

    New in version 4.1.

--hash-format=ALGORITHM
    Set the hashing algorithm used by SCons to ALGORITHM. This value determines the hashing algorithm used in generating content signatures, build signatures and CacheDir keys.

    The supported list of values are: md5, sha1 and sha256. However, the Python interpreter used to run scons must have the corresponding support available in the hashlib module to use the specified algorithm.

    If this option is omitted, the first supported hash format found is selected. Typically this is MD5, however, on a FIPS-compliant system using a version of Python older than 3.9, SHA1 or SHA256 is chosen as the default. Python 3.9 and onwards clients always default to MD5, even in FIPS mode.

    Specifying this option changes the name of the SConsign database. The default database is .sconsign.dblite. In the presence of this option, ALGORITHM is included in the name to indicate the difference, even if the argument is md5. For example, --hash-format=sha256 uses a SConsign database named .sconsign_sha256.dblite.

    New in version 4.1.

-H, --help-options
    Print the standard help message about SCons command-line options and exit.

-i, --ignore-errors
    Ignore all errors from commands executed to rebuild files.

-I directory, --include-dir=directory
    Specifies a directory to search for imported Python modules. If several -I options are used, the directories are searched in the order specified.

--ignore-virtualenv
    Suppress importing virtualenv-related variables to SCons.

--implicit-cache
    Cache implicit dependencies. This causes scons to use the implicit (scanned) dependencies from the last time it was run instead of scanning the files for implicit dependencies. This can significantly speed up SCons, but with the following limitations:

    scons will not detect changes to implicit dependency search paths (e.g. $CPPPATH, $LIBPATH) that would ordinarily cause different versions of same-named files to be used.

    scons will miss changes in the implicit dependencies in cases where a new implicit dependency is added earlier in the implicit dependency search path (e.g. $CPPPATH, $LIBPATH) than a current implicit dependency with the same name.

--implicit-deps-changed
    Forces SCons to ignore the cached implicit dependencies. This causes the implicit dependencies to be rescanned and recached. This implies --implicit-cache.

--implicit-deps-unchanged
    Force SCons to ignore changes in the implicit dependencies. This causes cached implicit dependencies to always be used. This implies --implicit-cache.

--install-sandbox=sandbox_path
    When using the Install builders, prepend sandbox_path to the installation paths such that all installed files will be placed under that directory. This option is unavailable if one of Install, InstallAs or InstallVersionedLib is not used in the SConscript files.

--interactive
    Starts SCons in interactive mode. The SConscript files are read once and a scons>>> prompt is printed. Targets may now be rebuilt by typing commands at interactive prompt without having to re-read the SConscript files and re-initialize the dependency graph from scratch.

    SCons interactive mode supports the following commands:

    build [OPTIONS] [TARGETS] ...
        Builds the specified TARGETS (and their dependencies) with the specified SCons command-line OPTIONS. b and scons are synonyms for build.

        The following SCons command-line options affect the build command:

            --cache-debug=FILE
            --cache-disable, --no-cache
            --cache-force, --cache-populate
            --cache-readonly
            --cache-show
            --debug=TYPE
            -i, --ignore-errors
            -j N, --jobs=N
            -k, --keep-going
            -n, --no-exec, --just-print, --dry-run, --recon
            -Q
            -s, --silent, --quiet
            --taskmastertrace=FILE
            --tree=OPTIONS

        Any other SCons command-line options that are specified do not cause errors but have no effect on the build command (mainly because they affect how the SConscript files are read, which only happens once at the beginning of interactive mode).

    clean [OPTIONS] [TARGETS] ...
        Cleans the specified TARGETS (and their dependencies) with the specified OPTIONS. c is a synonym. This command is itself a synonym for build --clean

    exit
        Exits SCons interactive mode. You can also exit by terminating input (Ctrl+D UNIX or Linux systems, (Ctrl+Z on Windows systems).

    help [COMMAND]
        Provides a help message about the commands available in SCons interactive mode. If COMMAND is specified, h and ? are synonyms.

    shell [COMMANDLINE]
        Executes the specified COMMANDLINE in a subshell. If no COMMANDLINE is specified, executes the interactive command interpreter specified in the SHELL environment variable (on UNIX and Linux systems) or the COMSPEC environment variable (on Windows systems). sh and ! are synonyms.

    version
        Prints SCons version information.

    An empty line repeats the last typed command. Command-line editing can be used if the readline module is available.

        $ scons --interactive
        scons: Reading SConscript files ...
        scons: done reading SConscript files.
        scons>>> build -n prog
        scons>>> exit

-j N, --jobs=N
    Specifies the maximum number of comcurrent jobs (commands) to run. If there is more than one -j option, the last one is effective.

-k, --keep-going
    Continue as much as possible after an error. The target that failed and those that depend on it will not be remade, but other targets specified on the command line will still be processed.

-m
    Ignored for compatibility with non-GNU versions of Make.

--max-drift=SECONDS
    Set the maximum expected drift in the modification time of files to SECONDS. This value determines how long a file must be unmodified before its cached content signature will be used instead of calculating a new content signature (hash) of the file's contents. The default value is 2 days, which means a file must have a modification time of at least two days ago in order to have its cached content signature used. A negative value means to never cache the content signature and to ignore the cached value if there already is one. A value of 0 means to always use the cached signature, no matter how old the file is.

--md5-chunksize=KILOBYTES
    A deprecated synonym for --hash-chunksize.

    Changed in version 4.2: deprecated.

-n, --no-exec, --just-print, --dry-run, --recon
    Set no-exec mode. Print the commands that would be executed to build any out-of-date targets, but do not execute those commands.

    Only target building is suppressed - any work in the build system that is done directly (in regular Python code) will still be carried out. You can add guards around code which should not be executed in no-exec mode by checking the value of the option at run time with GetOption:

        if not GetOption("no_exec"):
            # run regular instructions

    The output is a best effort, as SCons cannot always precisely determine what would be built. For example, if a file generated by a builder action is also used as a source in the build, that file is not available to scan for dependencies at all in an unbuilt tree, and may contain out of date information in a previously built tree.

    SCons cannot perform Configure checks in no-exec mode, as they would make changes to the filesystem (see $CONFIGUREDIR and $CONFIGURELOG). It can use stored information from a previous build, if it is not out of date, so a "priming" build may make subsequent no-exec runs more useful.

--no-site-dir
    Do not read site directories. Neither the standard site directories (site_scons) nor the path specified via a previous --site-dir option are added to the module search path sys.path, searched for a site_init.py file, or have their site_tools directory included in the tool search path. Can be overridden by a subequent --site-dir option.

--package-type=type
    The type of package to create when using the Package builder. Multiple types can be specified by using a comma-separated string, in which case SCons will try to build for all of those package types. Note this option is only available if the packaging tool has been enabled.

--profile=file
    Run SCons under the Python profiler and save the results to file. The results may be analyzed using the Python pstats module.

-q, --question
    Do not run any commands, or print anything. Just return an exit status that is zero if the specified targets are already up to date, non-zero otherwise.

-Q
    Suppress status messages about reading SConscript files, building targets and entering directories. Commands that are executed to rebuild target files are still printed.

--random
    Build dependencies in a random order. This is useful when building multiple trees simultaneously with caching enabled, to prevent multiple builds from simultaneously trying to build or retrieve the same target files.

-s, --silent, --quiet
    Silent. Do not print commands that are executed to rebuild target files. Also suppresses SCons status messages.

-S, --no-keep-going, --stop
    Ignored for compatibility with GNU Make

--site-dir=path
    Use path as the site directory rather than searching the list of default site directories. This directory will be prepended to sys.path, the module path/site_init.py will be loaded if it exists, and path/site_tools will be included in the tool search path. The option is not additive - if given more than once, the last path wins.

    The default set of site directories searched when --site-dir is not specified depends on the system platform, as follows. Users or system administrators can tune site-specific or project-specific SCons behavior by setting up a site directory in one or more of these locations. Directories are examined in the order given, from most generic ("system" directories) to most specific (in the current project), so the last-executed site_init.py file is the most specific one, giving it the chance to override everything else), and the directories are prepended to the paths, again so the last directory examined comes first in the resulting path.

    Windows:

            %ALLUSERSPROFILE%/scons/site_scons
            %LOCALAPPDATA%/scons/site_scons
            %APPDATA%/scons/site_scons
            %USERPROFILE%/.scons/site_scons
            ./site_scons

        Note earlier versions of the documentation listed a different path for the "system" site directory, this path is still checked but its use is discouraged:

            %ALLUSERSPROFILE%/Application Data/scons/site_scons

    Mac OS X:

            /Library/Application Support/SCons/site_scons
            /opt/local/share/scons/site_scons (for MacPorts)
            /sw/share/scons/site_scons (for Fink)
            $HOME/Library/Application Support/SCons/site_scons
            $HOME/.scons/site_scons
            ./site_scons

    Solaris:

            /opt/sfw/scons/site_scons
            /usr/share/scons/site_scons
            $HOME/.scons/site_scons
            ./site_scons

    Linux, HPUX, and other Posix-like systems:

            /usr/share/scons/site_scons
            $HOME/.scons/site_scons
            ./site_scons

--stack-size=KILOBYTES
    Set the size stack used to run threads to KILOBYTES. This value determines the stack size of the threads used to run jobs. These threads execute the actions of the builders for the nodes that are out-of-date. This option has no effect unless the number of concurrent build jobs is larger than one (as set by -j N or --jobs=N on the command line or SetOption in a script).

    Using a stack size that is too small may cause stack overflow errors. This usually shows up as segmentation faults that cause scons to abort before building anything. Using a stack size that is too large will cause scons to use more memory than required and may slow down the entire build process. The default value is to use a stack size of 256 kilobytes, which should be appropriate for most uses. You should not need to increase this value unless you encounter stack overflow errors.

-t, --touch
    Ignored for compatibility with GNU Make. (Touching a file to make it appear up-to-date is unnecessary when using scons.)

--taskmastertrace=file
    Prints trace information to the specified file about how the internal Taskmaster object evaluates and controls the order in which Nodes are built. A file name of - may be used to specify the standard output.

--tree=type[,type...]
    Prints a tree of the dependencies after each top-level target is built. This prints out some or all of the tree, in various formats, depending on the type specified:

    all
        Print the entire dependency tree after each top-level target is built. This prints out the complete dependency tree, including implicit dependencies and ignored dependencies.

    derived
        Restricts the tree output to only derived (target) files, not source files.

    linedraw
        Draw the tree output using Unicode line-drawing characters instead of plain ASCII text. This option acts as a modifier to the selected type(s). If specified alone, without any type, it behaves as if all had been specified.

        New in version 4.0.

    status
        Prints status information for each displayed node.

    prune
        Prunes the tree to avoid repeating dependency information for nodes that have already been displayed. Any node that has already been displayed will have its name printed in [square brackets], as an indication that the dependencies for that node can be found by searching for the relevant output higher up in the tree.

    Multiple type choices may be specified, separated by commas:

        # Prints only derived files, with status information:
        scons --tree=derived,status
        # Prints all dependencies of target, with status information
        # and pruning dependencies of already-visited Nodes:
        scons --tree=all,prune,status target

-u, --up, --search-up
    Walks up the directory structure until an SConstruct, Sconstruct, sconstruct, SConstruct.py, Sconstruct.py or sconstruct.py file is found, and uses that as the project top directory. If no targets are specified on the command line, only targets at or below the current directory will be built.

-U
    Works exactly the same way as the -u option except for the way default targets are handled. When this option is used and no targets are specified on the command line, all default targets that are defined in the SConscript file(s) in the current directory are built, regardless of what directory the resultant targets end up in.

-v, --version
    Print the scons version, copyright information, list of authors, and any other relevant information. Then exit.

-w, --print-directory
    Print a message containing the working directory before and after other processing.

--no-print-directory
    Turn off -w, even if it was turned on implicitly.

--warn=type, --warn=no-type
    Enable or disable (with the prefix "no-") warnings (--warning is a synonym). type specifies the type of warnings to be enabled or disabled:

    all
        All warnings.

    cache-version
        Warnings about the derived-file cache directory specified by CacheDir not using the latest configuration information. These warnings are enabled by default.

    cache-write-error
        Warnings about errors trying to write a copy of a built file to a specified derived-file cache specified by CacheDir. These warnings are disabled by default.

    cache-cleanup-error
        Warnings about errors when a file retrieved from the derived-file cache could not be removed.

    corrupt-sconsign
        Warnings about unfamiliar signature data in .sconsign files. These warnings are enabled by default.

    dependency
        Warnings about dependencies. These warnings are disabled by default.

    deprecated
        Warnings about use of currently deprecated features. These warnings are enabled by default. Not all deprecation warnings can be disabled with the --warn=no-deprecated option as some deprecated features which are late in the deprecation cycle may have been designated as mandatory warnings, and these will still display. Warnings for certain deprecated features may also be enabled or disabled individually; see below.

    duplicate-environment
        Warnings about attempts to specify a build of a target with two different construction environments that use the same action. These warnings are enabled by default.

    fortran-cxx-mix
        Warnings about linking Fortran and C++ object files in a single executable, which can yield unpredictable behavior with some compilers.

    future-reserved-variable
        Warnings about construction variables which are currently allowed, but will become reserved variables in a future release.

    future-deprecated
        Warnings about features that will be deprecated in the future. Such warnings are disabled by default. Enabling future deprecation warnings is recommended for projects that redistribute SCons configurations for other users to build, so that the project can be warned as soon as possible about to-be-deprecated features that may require changes to the configuration.

    link
        Warnings about link steps.

    misleading-keywords
        Warnings about the use of two commonly misspelled keywords targets and sources to Builder calls. The correct spelling is the singular form, even though target and source can themselves refer to lists of names or nodes.

    tool-qt-deprecated
        Warnings about the qt tool being deprecated. These warnings are disabled by default for the first phase of deprecation. Enable to be reminded about use of this tool module. New in version 4.3.

    no-object-count
        Warnings about the --debug=object feature not working when scons is run with the Python -O option or from optimized Python (.pyo) modules.

        Note the "no-" prefix is part of the name of this warning. Add an additional "-no" to disable.

    no-parallel-support
        Warnings about the version of Python not being able to support parallel builds when the -j option is used. These warnings are enabled by default.

        Note the "no-" prefix is part of the name of this warning. Add an additional "-no" to disable.

    python-version
        Warnings about running SCons using a version of Python that has been deprecated. These warnings are enabled by default.

    reserved-variable
        Warnings about attempts to set the reserved construction variable names $CHANGED_SOURCES, $CHANGED_TARGETS, $TARGET, $TARGETS, $SOURCE, $SOURCES, $UNCHANGED_SOURCES or $UNCHANGED_TARGETS. These warnings are disabled by default.

    stack-size
        Warnings about requests to set the stack size that could not be honored. These warnings are enabled by default.

    target-not-built
        Warnings about a build rule not building the expected targets. These warnings are disabled by default.

-Y repository, --repository=repository, --srcdir=repository
    Search the specified repository for any input and target files not found in the local directory hierarchy. Multiple -Y options may be specified, in which case the repositories are searched in the order specified.

SCONSCRIPT FILE REFERENCE

  SConscript Files

The build configuration is described by one or more files, known as SConscript files. There must be at least one file for a valid build (scons will quit if it does not find one). scons by default looks for this file by the name SConstruct in the directory from which you run scons, though if necessary, also looks for alternative file names Sconstruct, sconstruct, SConstruct.py, Sconstruct.py and sconstruct.py in that order. A different file name (which can include a pathname part) may be specified via the -f option. Except for the SConstruct file, these files are not searched for automatically; you add additional configuration files to the build by calling the SConscript function. This allows parts of the build to be conditionally included or excluded at run-time depending on how scons is invoked.

Each SConscript file in a build configuration is invoked independently in a separate context. This provides necessary isolation so that different parts of the build don't accidentally step on each other. You have to be explicit about sharing information, by using the Export function or the exports argument to the SConscript function, as well as the Return function in a called SConscript file, and comsume shared information by using the Import function.

The following sections describe the various SCons facilities that can be used in SConscript files. Quick links:
    Construction Environments
    Tools
    Builder Methods
    Functions and Environment Methods
    SConscript Variables
    Construction Variables
    Configure Contexts
    Command-Line Construction Variables
    Node Objects

  Construction Environments

A Construction Environment is the basic means by which you communicate build information to SCons. A new construction environment is created using the Environment function:

    env = Environment()

Construction environment attributes called Construction Variables may be set either by specifying them as keyword arguments when the object is created or by assigning them a value after the object is created. These two are nominally equivalent:

    env = Environment(FOO='foo')
    env['FOO'] = 'foo'

Note that certain settings which affect tool detection are referenced only when the tools are initializided, so you either need either to supply them as part of the call to Environment, or defer tool initialization. For example, initializing the Microsoft Visual C++ version you wish to use:

    # initializes msvc to v14.1
    env = Environment(MSVC_VERSION="14.1")
    env = Environment()
    # msvc tool was initialized to default, does not reinitialize
    env['MSVC_VERSION'] = "14.1"
    env = Environment(tools=[])
    env['MSVC_VERSION'] = "14.1"
    # msvc tool initialization was deferred, so will pick up new value
    env.Tool('default')

As a convenience, construction variables may also be set or modified by the parse_flags keyword argument during object creation, which has the effect of the env.MergeFlags method being applied to the argument value after all other processing is completed. This is useful either if the exact content of the flags is unknown (for example, read from a control file) or if the flags need to be distributed to a number of construction variables. env.ParseFlags describes how these arguments are distributed to construction variables.

    env = Environment(parse_flags='-Iinclude -DEBUG -lm')

This example adds 'include' to the $CPPPATH construction variable, 'EBUG' to $CPPDEFINES, and 'm' to $LIBS.

An existing construction environment can be duplicated by calling the env.Clone method. Without arguments, it will be a copy with the same settings. Otherwise, env.Clone takes the same arguments as Environment, and uses the arguments to create a modified copy.

SCons provides a special construction environment called the Default Environment. The default environment is used only for global functions, that is, construction activities called without the context of a regular construction environment. See DefaultEnvironment for more information.

By default, a new construction environment is initialized with a set of builder methods and construction variables that are appropriate for the current platform. The optional platform keyword argument may be used to specify that the construction environment should be initialized for a different platform:

    env = Environment(platform='cygwin')

Specifying a platform initializes the appropriate construction variables in the environment to use and generate file names with prefixes and suffixes appropriate for that platform.

Note that the win32 platform adds the SystemDrive and SystemRoot variables from the user's external environment to the construction environment's ENV dictionary. This is so that any executed commands that use sockets to connect with other systems will work on Windows systems.

The platform argument may be a string value representing one of the pre-defined platforms (aix, cygwin, darwin, hpux, irix, os2, posix, sunos or win32), or it may be be a callable platform object returned by a call to Platform selecting a pre-defined platform, or it may be a user-supplied callable, in which case the Environment method will call it to update the new construction environment:

    def my_platform(env):
        env['VAR'] = 'xyzzy'
    env = Environment(platform=my_platform)

Note that supplying a non-default platform or custom fuction for initialization may bypass settings that should happen for the host system and should be used with care. It is most useful in the case where the platform is an alternative for the one that would be auto-detected, such as platform="cygwin" on a system which would otherwise identify as win32.

The optional tools and toolpath keyword arguments affect the way tools available to the environment are initialized. See the section called “Tools” for details.

The optional variables keyword argument allows passing a Variables object which will be used in the initialization of the construction environment See the section called “Command-Line Construction Variables” for details.

  Tools

SCons has many included tool modules (more properly, tool specification modules) which are used to help initialize the construction environment prior to building, and more can be written to suit a particular purpose, or added from external sources (a repository of constributed tools is available). More information on writing custom tools can be found in the Extending SCons section and specifically Tool Modules.

An SCons tool is only responsible for setup. For example, if an SConscript file declares the need to construct an object file from a C-language source file by calling the Object builder, then a tool module representing an available C compiler needs to have run first, to set up that builder and all the construction variables it needs in the associated construction environment. The tool itself is not called in the process of the build. Tool setup happens when a construction environment is constructed, and in the basic case needs no intervention - platform-specific lists of default tools are used to examine the specific capabilities of that platform and configure the environment, skipping those tools which are not applicable.

If necessary, a specific set of tools to initialize in an environment during creation may be specified using the optional keyword argument tools. tools must be a list, even if there are one (or zero) tools. This is useful to override the defaults, to specify non-default built-in tools, and to cause added tools to be called:

    env = Environment(tools=['msvc', 'lex'])

The tools argument overrides the default tool list, it does not add to it, so be sure to include all the tools you need. For example, if you are building a c/c++ program, you must specify a tool for at least a compiler and a linker, as in tools=['clang', 'link'].

If the tools argument is omitted, or if tools includes the reserved name 'default', then SCons will auto-detect usable tools, using the search path from the execution environment (that is, env['ENV']['PATH']) for looking up any external programs, and the platform name in effect to determine the default tools for that platform. Note the contents of PATH from the external environment os.environ is not used. Changing the PATH in the execution environment after the construction environment is constructed will not cause the tools to be re-detected.

Tools can also be directly called by using the Tool method (see below).

SCons supports the following tool specifications out of the box:

386asm
    Sets construction variables for the 386ASM assembler for the Phar Lap ETS embedded operating system.

    Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

    Uses: $CC, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

aixc++
    Sets construction variables for the IMB xlc / Visual Age C++ compiler.

    Sets: $CXX, $CXXVERSION, $SHCXX, $SHOBJSUFFIX.

aixcc
    Sets construction variables for the IBM xlc / Visual Age C compiler.

    Sets: $CC, $CCVERSION, $SHCC.

aixf77
    Sets construction variables for the IBM Visual Age f77 Fortran compiler.

    Sets: $F77, $SHF77.

aixlink
    Sets construction variables for the IBM Visual Age linker.

    Sets: $LINKFLAGS, $SHLIBSUFFIX, $SHLINKFLAGS.

applelink
    Sets construction variables for the Apple linker (similar to the GNU linker).

    Sets: $APPLELINK_COMPATIBILITY_VERSION, $APPLELINK_CURRENT_VERSION, $APPLELINK_NO_COMPATIBILITY_VERSION, $APPLELINK_NO_CURRENT_VERSION, $FRAMEWORKPATHPREFIX, $LDMODULECOM, $LDMODULEFLAGS, $LDMODULEPREFIX, $LDMODULESUFFIX, $LINKCOM, $SHLINKCOM, $SHLINKFLAGS, $_APPLELINK_COMPATIBILITY_VERSION, $_APPLELINK_CURRENT_VERSION, $_FRAMEWORKPATH, $_FRAMEWORKS.

    Uses: $FRAMEWORKSFLAGS.

ar
    Sets construction variables for the ar library archiver.

    Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX, $RANLIB, $RANLIBCOM, $RANLIBFLAGS.

as
    Sets construction variables for the as assembler.

    Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

    Uses: $CC, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

bcc32
    Sets construction variables for the bcc32 compiler.

    Sets: $CC, $CCCOM, $CCFLAGS, $CFILESUFFIX, $CFLAGS, $CPPDEFPREFIX, $CPPDEFSUFFIX, $INCPREFIX, $INCSUFFIX, $SHCC, $SHCCCOM, $SHCCFLAGS, $SHCFLAGS, $SHOBJSUFFIX.

    Uses: $_CPPDEFFLAGS, $_CPPINCFLAGS.

cc
    Sets construction variables for generic POSIX C compilers.

    Sets: $CC, $CCCOM, $CCDEPFLAGS, $CCFLAGS, $CFILESUFFIX, $CFLAGS, $CPPDEFPREFIX, $CPPDEFSUFFIX, $FRAMEWORKPATH, $FRAMEWORKS, $INCPREFIX, $INCSUFFIX, $SHCC, $SHCCCOM, $SHCCFLAGS, $SHCFLAGS, $SHOBJSUFFIX.

    Uses: $CCCOMSTR, $PLATFORM, $SHCCCOMSTR.

clang
    Set construction variables for the Clang C compiler.

    Sets: $CC, $CCDEPFLAGS, $CCVERSION, $SHCCFLAGS.

clangxx
    Set construction variables for the Clang C++ compiler.

    Sets: $CXX, $CXXVERSION, $SHCXXFLAGS, $SHOBJSUFFIX, $STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME.

compilation_db
    Sets up CompilationDatabase builder which generates a clang tooling compatible compilation database.

    Sets: $COMPILATIONDB_COMSTR, $COMPILATIONDB_PATH_FILTER, $COMPILATIONDB_USE_ABSPATH.

cvf
    Sets construction variables for the Compaq Visual Fortran compiler.

    Sets: $FORTRAN, $FORTRANCOM, $FORTRANMODDIR, $FORTRANMODDIRPREFIX, $FORTRANMODDIRSUFFIX, $FORTRANPPCOM, $OBJSUFFIX, $SHFORTRANCOM, $SHFORTRANPPCOM.

    Uses: $CPPFLAGS, $FORTRANFLAGS, $SHFORTRANFLAGS, $_CPPDEFFLAGS, $_FORTRANINCFLAGS, $_FORTRANMODFLAG.

cXX
    Sets construction variables for generic POSIX C++ compilers.

    Sets: $CPPDEFPREFIX, $CPPDEFSUFFIX, $CXX, $CXXCOM, $CXXFILESUFFIX, $CXXFLAGS, $INCPREFIX, $INCSUFFIX, $OBJSUFFIX, $SHCXX, $SHCXXCOM, $SHCXXFLAGS, $SHOBJSUFFIX.

    Uses: $CXXCOMSTR, $SHCXXCOMSTR.

cyglink
    Set construction variables for cygwin linker/loader.

    Sets: $IMPLIBPREFIX, $IMPLIBSUFFIX, $LDMODULEVERSIONFLAGS, $LINKFLAGS, $RPATHPREFIX, $RPATHSUFFIX, $SHLIBPREFIX, $SHLIBSUFFIX, $SHLIBVERSIONFLAGS, $SHLINKCOM, $SHLINKFLAGS, $_LDMODULEVERSIONFLAGS, $_SHLIBVERSIONFLAGS.

default
    Sets construction variables for a default list of Tool modules. Use default in the tools list to retain the original defaults, since the tools parameter is treated as a literal statement of the tools to be made available in that construction environment, not an addition.

    The list of tools selected by default is not static, but is dependent both on the platform and on the software installed on the platform. Some tools will not initialize if an underlying command is not found, and some tools are selected from a list of choices on a first-found basis. The finished tool list can be examined by inspecting the $TOOLS construction variable in the construction environment.

    On all platforms, the tools from the following list are selected if their respective conditions are met: filesystem;, wix, lex, yacc, rpcgen, swig, jar, javac, javah, rmic, dvipdf, dvips, gs, tex, latex, pdflatex, pdftex, tar, zip, textfile.

    On Linux systems, the default tools list selects (first-found): a C compiler from gcc, intelc, icc, cc; a C++ compiler from g++, intelc, icc, cXX; an assembler from gas, nasm, masm; a linker from gnulink, ilink; a Fortran compiler from gfortran, g77, ifort, ifl, f95, f90, f77; and a static archiver ar. It also selects all found from the list m4 rpm.

    On Windows systems, the default tools list selects (first-found): a C compiler from msvc, mingw, gcc, intelc, icl, icc, cc, bcc32; a C++ compiler from msvc, intelc, icc, g++, cXX, bcc32; an assembler from masm, nasm, gas, 386asm; a linker from mslink, gnulink, ilink, linkloc, ilink32; a Fortran compiler from gfortran, g77, ifl, cvf, f95, f90, fortran; and a static archiver from mslib, ar, tlib; It also selects all found from the list msvs, midl.

    On MacOS systems, the default tools list selects (first-found): a C compiler from gcc, cc; a C++ compiler from g++, cXX; an assembler as; a linker from applelink, gnulink; a Fortran compiler from gfortran, f95, f90, g77; and a static archiver ar. It also selects all found from the list m4, rpm.

    Default lists for other platforms can be found by examining the scons source code (see SCons/Tool/__init__.py).

dmd
    Sets construction variables for D language compiler DMD.

    Sets: $DC, $DCOM, $DDEBUG, $DDEBUGPREFIX, $DDEBUGSUFFIX, $DFILESUFFIX, $DFLAGPREFIX, $DFLAGS, $DFLAGSUFFIX, $DINCPREFIX, $DINCSUFFIX, $DLIB, $DLIBCOM, $DLIBDIRPREFIX, $DLIBDIRSUFFIX, $DLIBFLAGPREFIX, $DLIBFLAGSUFFIX, $DLIBLINKPREFIX, $DLIBLINKSUFFIX, $DLINK, $DLINKCOM, $DLINKFLAGPREFIX, $DLINKFLAGS, $DLINKFLAGSUFFIX, $DPATH, $DRPATHPREFIX, $DRPATHSUFFIX, $DVERPREFIX, $DVERSIONS, $DVERSUFFIX, $SHDC, $SHDCOM, $SHDLIBVERSIONFLAGS, $SHDLINK, $SHDLINKCOM, $SHDLINKFLAGS.

docbook
    This tool tries to make working with Docbook in SCons a little easier. It provides several toolchains for creating different output formats, like HTML or PDF. Contained in the package is a distribution of the Docbook XSL stylesheets as of version 1.76.1. As long as you don't specify your own stylesheets for customization, these official versions are picked as default...which should reduce the inevitable setup hassles for you.

    Implicit dependencies to images and XIncludes are detected automatically if you meet the HTML requirements. The additional stylesheet utils/xmldepend.xsl by Paul DuBois is used for this purpose.

    Note, that there is no support for XML catalog resolving offered! This tool calls the XSLT processors and PDF renderers with the stylesheets you specified, that's it. The rest lies in your hands and you still have to know what you're doing when resolving names via a catalog.

    For activating the tool "docbook", you have to add its name to the Environment constructor, like this

        env = Environment(tools=['docbook'])

    On its startup, the docbook tool tries to find a required xsltproc processor, and a PDF renderer, e.g. fop. So make sure that these are added to your system's environment PATH and can be called directly without specifying their full path.

    For the most basic processing of Docbook to HTML, you need to have installed

        • the Python lxml binding to libxml2, or

        • a standalone XSLT processor, currently detected are xsltproc, saxon, saxon-xslt and xalan.

    Rendering to PDF requires you to have one of the applications fop or xep installed.

    Creating a HTML or PDF document is very simple and straightforward. Say

        env = Environment(tools=['docbook'])
        env.DocbookHtml('manual.html', 'manual.xml')
        env.DocbookPdf('manual.pdf', 'manual.xml')

    to get both outputs from your XML source manual.xml. As a shortcut, you can give the stem of the filenames alone, like this:

        env = Environment(tools=['docbook'])
        env.DocbookHtml('manual')
        env.DocbookPdf('manual')

    and get the same result. Target and source lists are also supported:

        env = Environment(tools=['docbook'])
        env.DocbookHtml(['manual.html','reference.html'], ['manual.xml','reference.xml'])

    or even

        env = Environment(tools=['docbook'])
        env.DocbookHtml(['manual','reference'])

        Important
        Whenever you leave out the list of sources, you may not specify a file extension! The Tool uses the given names as file stems, and adds the suffixes for target and source files accordingly.

    The rules given above are valid for the Builders DocbookHtml, DocbookPdf, DocbookEpub, DocbookSlidesPdf and DocbookXInclude. For the DocbookMan transformation you can specify a target name, but the actual output names are automatically set from the refname entries in your XML source.

    The Builders DocbookHtmlChunked, DocbookHtmlhelp and DocbookSlidesHtml are special, in that:

        1. they create a large set of files, where the exact names and their number depend on the content of the source file, and

        2. the main target is always named index.html, i.e. the output name for the XSL transformation is not picked up by the stylesheets.

    As a result, there is simply no use in specifying a target HTML name. So the basic syntax for these builders is always:

        env = Environment(tools=['docbook'])
        env.DocbookHtmlhelp('manual')

    If you want to use a specific XSL file, you can set the additional xsl parameter to your Builder call as follows:

        env.DocbookHtml('other.html', 'manual.xml', xsl='html.xsl')

    Since this may get tedious if you always use the same local naming for your customized XSL files, e.g. html.xsl for HTML and pdf.xsl for PDF output, a set of variables for setting the default XSL name is provided. These are:

        DOCBOOK_DEFAULT_XSL_HTML
        DOCBOOK_DEFAULT_XSL_HTMLCHUNKED
        DOCBOOK_DEFAULT_XSL_HTMLHELP
        DOCBOOK_DEFAULT_XSL_PDF
        DOCBOOK_DEFAULT_XSL_EPUB
        DOCBOOK_DEFAULT_XSL_MAN
        DOCBOOK_DEFAULT_XSL_SLIDESPDF
        DOCBOOK_DEFAULT_XSL_SLIDESHTML

    and you can set them when constructing your environment:

        env = Environment(
            tools=['docbook'],
            DOCBOOK_DEFAULT_XSL_HTML='html.xsl',
            DOCBOOK_DEFAULT_XSL_PDF='pdf.xsl',
        )
        env.DocbookHtml('manual')  # now uses html.xsl

    Sets: $DOCBOOK_DEFAULT_XSL_EPUB, $DOCBOOK_DEFAULT_XSL_HTML, $DOCBOOK_DEFAULT_XSL_HTMLCHUNKED, $DOCBOOK_DEFAULT_XSL_HTMLHELP, $DOCBOOK_DEFAULT_XSL_MAN, $DOCBOOK_DEFAULT_XSL_PDF, $DOCBOOK_DEFAULT_XSL_SLIDESHTML, $DOCBOOK_DEFAULT_XSL_SLIDESPDF, $DOCBOOK_FOP, $DOCBOOK_FOPCOM, $DOCBOOK_FOPFLAGS, $DOCBOOK_XMLLINT, $DOCBOOK_XMLLINTCOM, $DOCBOOK_XMLLINTFLAGS, $DOCBOOK_XSLTPROC, $DOCBOOK_XSLTPROCCOM, $DOCBOOK_XSLTPROCFLAGS, $DOCBOOK_XSLTPROCPARAMS.

    Uses: $DOCBOOK_FOPCOMSTR, $DOCBOOK_XMLLINTCOMSTR, $DOCBOOK_XSLTPROCCOMSTR.

dvi
    Attaches the DVI builder to the construction environment.

dvipdf
    Sets construction variables for the dvipdf utility.

    Sets: $DVIPDF, $DVIPDFCOM, $DVIPDFFLAGS.

    Uses: $DVIPDFCOMSTR.

dvips
    Sets construction variables for the dvips utility.

    Sets: $DVIPS, $DVIPSFLAGS, $PSCOM, $PSPREFIX, $PSSUFFIX.

    Uses: $PSCOMSTR.

f03
    Set construction variables for generic POSIX Fortran 03 compilers.

    Sets: $F03, $F03COM, $F03FLAGS, $F03PPCOM, $SHF03, $SHF03COM, $SHF03FLAGS, $SHF03PPCOM, $_F03INCFLAGS.

    Uses: $F03COMSTR, $F03PPCOMSTR, $FORTRANCOMMONFLAGS, $SHF03COMSTR, $SHF03PPCOMSTR.

f08
    Set construction variables for generic POSIX Fortran 08 compilers.

    Sets: $F08, $F08COM, $F08FLAGS, $F08PPCOM, $SHF08, $SHF08COM, $SHF08FLAGS, $SHF08PPCOM, $_F08INCFLAGS.

    Uses: $F08COMSTR, $F08PPCOMSTR, $FORTRANCOMMONFLAGS, $SHF08COMSTR, $SHF08PPCOMSTR.

f77
    Set construction variables for generic POSIX Fortran 77 compilers.

    Sets: $F77, $F77COM, $F77FILESUFFIXES, $F77FLAGS, $F77PPCOM, $F77PPFILESUFFIXES, $FORTRAN, $FORTRANCOM, $FORTRANFLAGS, $SHF77, $SHF77COM, $SHF77FLAGS, $SHF77PPCOM, $SHFORTRAN, $SHFORTRANCOM, $SHFORTRANFLAGS, $SHFORTRANPPCOM, $_F77INCFLAGS.

    Uses: $F77COMSTR, $F77PPCOMSTR, $FORTRANCOMMONFLAGS, $FORTRANCOMSTR, $FORTRANFLAGS, $FORTRANPPCOMSTR, $SHF77COMSTR, $SHF77PPCOMSTR, $SHFORTRANCOMSTR, $SHFORTRANFLAGS, $SHFORTRANPPCOMSTR.

f90
    Set construction variables for generic POSIX Fortran 90 compilers.

    Sets: $F90, $F90COM, $F90FLAGS, $F90PPCOM, $SHF90, $SHF90COM, $SHF90FLAGS, $SHF90PPCOM, $_F90INCFLAGS.

    Uses: $F90COMSTR, $F90PPCOMSTR, $FORTRANCOMMONFLAGS, $SHF90COMSTR, $SHF90PPCOMSTR.

f95
    Set construction variables for generic POSIX Fortran 95 compilers.

    Sets: $F95, $F95COM, $F95FLAGS, $F95PPCOM, $SHF95, $SHF95COM, $SHF95FLAGS, $SHF95PPCOM, $_F95INCFLAGS.

    Uses: $F95COMSTR, $F95PPCOMSTR, $FORTRANCOMMONFLAGS, $SHF95COMSTR, $SHF95PPCOMSTR.

fortran
    Set construction variables for generic POSIX Fortran compilers.

    Sets: $FORTRAN, $FORTRANCOM, $FORTRANFLAGS, $SHFORTRAN, $SHFORTRANCOM, $SHFORTRANFLAGS, $SHFORTRANPPCOM.

    Uses: $CPPFLAGS, $FORTRANCOMSTR, $FORTRANPPCOMSTR, $SHFORTRANCOMSTR, $SHFORTRANPPCOMSTR, $_CPPDEFFLAGS.

g++
    Set construction variables for the g++ C++ compiler.

    Sets: $CXX, $CXXVERSION, $SHCXXFLAGS, $SHOBJSUFFIX.

g77
    Set construction variables for the g77 Fortran compiler.

    Sets: $F77, $F77COM, $F77FILESUFFIXES, $F77PPCOM, $F77PPFILESUFFIXES, $FORTRAN, $FORTRANCOM, $FORTRANPPCOM, $SHF77, $SHF77COM, $SHF77FLAGS, $SHF77PPCOM, $SHFORTRAN, $SHFORTRANCOM, $SHFORTRANFLAGS, $SHFORTRANPPCOM.

    Uses: $F77FLAGS, $FORTRANCOMMONFLAGS, $FORTRANFLAGS.

gas
    Sets construction variables for the gas assembler. Calls the as tool.

    Sets: $AS.

gcc
    Set construction variables for the gcc C compiler.

    Sets: $CC, $CCDEPFLAGS, $CCVERSION, $SHCCFLAGS.

gdc
    Sets construction variables for the D language compiler GDC.

    Sets: $DC, $DCOM, $DDEBUG, $DDEBUGPREFIX, $DDEBUGSUFFIX, $DFILESUFFIX, $DFLAGPREFIX, $DFLAGS, $DFLAGSUFFIX, $DINCPREFIX, $DINCSUFFIX, $DLIB, $DLIBCOM, $DLIBDIRPREFIX, $DLIBDIRSUFFIX, $DLIBFLAGPREFIX, $DLIBFLAGSUFFIX, $DLIBLINKPREFIX, $DLIBLINKSUFFIX, $DLINK, $DLINKCOM, $DLINKFLAGPREFIX, $DLINKFLAGS, $DLINKFLAGSUFFIX, $DPATH, $DRPATHPREFIX, $DRPATHSUFFIX, $DVERPREFIX, $DVERSIONS, $DVERSUFFIX, $SHDC, $SHDCOM, $SHDLIBVERSIONFLAGS, $SHDLINK, $SHDLINKCOM, $SHDLINKFLAGS.

gettext
    This is actually a toolset, which supports internationalization and localization of software being constructed with SCons. The toolset loads following tools:

        • xgettext - to extract internationalized messages from source code to POT file(s),

        • msginit - may be optionally used to initialize PO files,

        • msgmerge - to update PO files, that already contain translated messages,

        • msgfmt - to compile textual PO file to binary installable MO file.

    When you enable gettext, it internally loads all abovementioned tools, so you're encouraged to see their individual documentation.

    Each of the above tools provides its own builder(s) which may be used to perform particular activities related to software internationalization. You may be however interested in top-level Translate builder.

    To use gettext tools add 'gettext' tool to your environment:

          env = Environment( tools = ['default', 'gettext'] )

gfortran
    Sets construction variables for the GNU Fortran compiler. Calls the fortran Tool module to set variables.

    Sets: $F77, $F90, $F95, $FORTRAN, $SHF77, $SHF77FLAGS, $SHF90, $SHF90FLAGS, $SHF95, $SHF95FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

gnulink
    Set construction variables for GNU linker/loader.

    Sets: $LDMODULEVERSIONFLAGS, $RPATHPREFIX, $RPATHSUFFIX, $SHLIBVERSIONFLAGS, $SHLINKFLAGS, $_LDMODULESONAME, $_SHLIBSONAME.

gs
    This Tool sets the required construction variables for working with the Ghostscript software. It also registers an appropriate Action with the PDF Builder, such that the conversion from PS/EPS to PDF happens automatically for the TeX/LaTeX toolchain. Finally, it adds an explicit Gs Builder for Ghostscript to the environment.

    Sets: $GS, $GSCOM, $GSFLAGS.

    Uses: $GSCOMSTR.

hpc++
    Set construction variables for the compilers aCC on HP/UX systems.

hpcc
    Set construction variables for aCC compilers on HP/UX systems. Calls the cXX tool for additional variables.

    Sets: $CXX, $CXXVERSION, $SHCXXFLAGS.

hplink
    Sets construction variables for the linker on HP/UX systems.

    Sets: $LINKFLAGS, $SHLIBSUFFIX, $SHLINKFLAGS.

icc
    Sets construction variables for the icc compiler on OS/2 systems.

    Sets: $CC, $CCCOM, $CFILESUFFIX, $CPPDEFPREFIX, $CPPDEFSUFFIX, $CXXCOM, $CXXFILESUFFIX, $INCPREFIX, $INCSUFFIX.

    Uses: $CCFLAGS, $CFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

icl
    Sets construction variables for the Intel C/C++ compiler. Calls the intelc Tool module to set its variables.

ifl
    Sets construction variables for the Intel Fortran compiler.

    Sets: $FORTRAN, $FORTRANCOM, $FORTRANPPCOM, $SHFORTRANCOM, $SHFORTRANPPCOM.

    Uses: $CPPFLAGS, $FORTRANFLAGS, $_CPPDEFFLAGS, $_FORTRANINCFLAGS.

ifort
    Sets construction variables for newer versions of the Intel Fortran compiler for Linux.

    Sets: $F77, $F90, $F95, $FORTRAN, $SHF77, $SHF77FLAGS, $SHF90, $SHF90FLAGS, $SHF95, $SHF95FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

ilink
    Sets construction variables for the ilink linker on OS/2 systems.

    Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS.

ilink32
    Sets construction variables for the Borland ilink32 linker.

    Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS.

install
    Sets construction variables for file and directory installation.

    Sets: $INSTALL, $INSTALLSTR.

intelc
    Sets construction variables for the Intel C/C++ compiler (Linux and Windows, version 7 and later). Calls the gcc or msvc (on Linux and Windows, respectively) tool to set underlying variables.

    Sets: $AR, $CC, $CXX, $INTEL_C_COMPILER_VERSION, $LINK.

jar
    Sets construction variables for the jar utility.

    Sets: $JAR, $JARCOM, $JARFLAGS, $JARSUFFIX.

    Uses: $JARCOMSTR.

javac
    Sets construction variables for the javac compiler.

    Sets: $JAVABOOTCLASSPATH, $JAVAC, $JAVACCOM, $JAVACFLAGS, $JAVACLASSPATH, $JAVACLASSSUFFIX, $JAVAINCLUDES, $JAVASOURCEPATH, $JAVASUFFIX.

    Uses: $JAVACCOMSTR.

javah
    Sets construction variables for the javah tool.

    Sets: $JAVACLASSSUFFIX, $JAVAH, $JAVAHCOM, $JAVAHFLAGS.

    Uses: $JAVACLASSPATH, $JAVAHCOMSTR.

latex
    Sets construction variables for the latex utility.

    Sets: $LATEX, $LATEXCOM, $LATEXFLAGS.

    Uses: $LATEXCOMSTR.

ldc
    Sets construction variables for the D language compiler LDC2.

    Sets: $DC, $DCOM, $DDEBUG, $DDEBUGPREFIX, $DDEBUGSUFFIX, $DFILESUFFIX, $DFLAGPREFIX, $DFLAGS, $DFLAGSUFFIX, $DINCPREFIX, $DINCSUFFIX, $DLIB, $DLIBCOM, $DLIBDIRPREFIX, $DLIBDIRSUFFIX, $DLIBFLAGPREFIX, $DLIBFLAGSUFFIX, $DLIBLINKPREFIX, $DLIBLINKSUFFIX, $DLINK, $DLINKCOM, $DLINKFLAGPREFIX, $DLINKFLAGS, $DLINKFLAGSUFFIX, $DPATH, $DRPATHPREFIX, $DRPATHSUFFIX, $DVERPREFIX, $DVERSIONS, $DVERSUFFIX, $SHDC, $SHDCOM, $SHDLIBVERSIONFLAGS, $SHDLINK, $SHDLINKCOM, $SHDLINKFLAGS.

lex
    Sets construction variables for the lex lexical analyser.

    Sets: $LEX, $LEXCOM, $LEXFLAGS, $LEXUNISTD.

    Uses: $LEXCOMSTR, $LEXFLAGS, $LEX_HEADER_FILE, $LEX_TABLES_FILE.

link
    Sets construction variables for generic POSIX linkers. This is a "smart" linker tool which selects a compiler to complete the linking based on the types of source files.

    Sets: $LDMODULE, $LDMODULECOM, $LDMODULEFLAGS, $LDMODULENOVERSIONSYMLINKS, $LDMODULEPREFIX, $LDMODULESUFFIX, $LDMODULEVERSION, $LDMODULEVERSIONFLAGS, $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS, $SHLIBSUFFIX, $SHLINK, $SHLINKCOM, $SHLINKFLAGS, $__LDMODULEVERSIONFLAGS, $__SHLIBVERSIONFLAGS.

    Uses: $LDMODULECOMSTR, $LINKCOMSTR, $SHLINKCOMSTR.

linkloc
    Sets construction variables for the LinkLoc linker for the Phar Lap ETS embedded operating system.

    Sets: $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS, $SHLINK, $SHLINKCOM, $SHLINKFLAGS.

    Uses: $LINKCOMSTR, $SHLINKCOMSTR.

m4
    Sets construction variables for the m4 macro processor.

    Sets: $M4, $M4COM, $M4FLAGS.

    Uses: $M4COMSTR.

masm
    Sets construction variables for the Microsoft assembler.

    Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

    Uses: $ASCOMSTR, $ASPPCOMSTR, $CPPFLAGS, $_CPPDEFFLAGS, $_CPPINCFLAGS.

midl
    Sets construction variables for the Microsoft IDL compiler.

    Sets: $MIDL, $MIDLCOM, $MIDLFLAGS.

    Uses: $MIDLCOMSTR.

mingw
    Sets construction variables for MinGW (Minimal Gnu on Windows).

    Sets: $AS, $CC, $CXX, $LDMODULECOM, $LIBPREFIX, $LIBSUFFIX, $OBJSUFFIX, $RC, $RCCOM, $RCFLAGS, $RCINCFLAGS, $RCINCPREFIX, $RCINCSUFFIX, $SHCCFLAGS, $SHCXXFLAGS, $SHLINKCOM, $SHLINKFLAGS, $SHOBJSUFFIX, $WINDOWSDEFPREFIX, $WINDOWSDEFSUFFIX.

    Uses: $RCCOMSTR, $SHLINKCOMSTR.

msgfmt
    This scons tool is a part of scons gettext toolset. It provides scons interface to msgfmt(1) command, which generates binary message catalog (MO) from a textual translation description (PO).

    Sets: $MOSUFFIX, $MSGFMT, $MSGFMTCOM, $MSGFMTCOMSTR, $MSGFMTFLAGS, $POSUFFIX.

    Uses: $LINGUAS_FILE.

msginit
    This scons tool is a part of scons gettext toolset. It provides scons interface to msginit(1) program, which creates new PO file, initializing the meta information with values from user's environment (or options).

    Sets: $MSGINIT, $MSGINITCOM, $MSGINITCOMSTR, $MSGINITFLAGS, $POAUTOINIT, $POCREATE_ALIAS, $POSUFFIX, $POTSUFFIX, $_MSGINITLOCALE.

    Uses: $LINGUAS_FILE, $POAUTOINIT, $POTDOMAIN.

msgmerge
    This scons tool is a part of scons gettext toolset. It provides scons interface to msgmerge(1) command, which merges two Uniform style .po files together.

    Sets: $MSGMERGE, $MSGMERGECOM, $MSGMERGECOMSTR, $MSGMERGEFLAGS, $POSUFFIX, $POTSUFFIX, $POUPDATE_ALIAS.

    Uses: $LINGUAS_FILE, $POAUTOINIT, $POTDOMAIN.

mslib
    Sets construction variables for the Microsoft mslib library archiver.

    Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

    Uses: $ARCOMSTR.

mslink
    Sets construction variables for the Microsoft linker.

    Sets: $LDMODULE, $LDMODULECOM, $LDMODULEFLAGS, $LDMODULEPREFIX, $LDMODULESUFFIX, $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX, $LINK, $LINKCOM, $LINKFLAGS, $REGSVR, $REGSVRCOM, $REGSVRFLAGS, $SHLINK, $SHLINKCOM, $SHLINKFLAGS, $WINDOWSDEFPREFIX, $WINDOWSDEFSUFFIX, $WINDOWSEXPPREFIX, $WINDOWSEXPSUFFIX, $WINDOWSPROGMANIFESTPREFIX, $WINDOWSPROGMANIFESTSUFFIX, $WINDOWSSHLIBMANIFESTPREFIX, $WINDOWSSHLIBMANIFESTSUFFIX, $WINDOWS_INSERT_DEF.

    Uses: $LDMODULECOMSTR, $LINKCOMSTR, $REGSVRCOMSTR, $SHLINKCOMSTR.

mssdk
    Sets variables for Microsoft Platform SDK and/or Windows SDK. Note that unlike most other Tool modules, mssdk does not set construction variables, but sets the environment variables in the environment SCons uses to execute the Microsoft toolchain: %INCLUDE%, %LIB%, %LIBPATH% and %PATH%.

    Uses: $MSSDK_DIR, $MSSDK_VERSION, $MSVS_VERSION.

msvc
    Sets construction variables for the Microsoft Visual C++ compiler.

    Sets: $BUILDERS, $CC, $CCCOM, $CCDEPFLAGS, $CCFLAGS, $CCPCHFLAGS, $CCPDBFLAGS, $CFILESUFFIX, $CFLAGS, $CPPDEFPREFIX, $CPPDEFSUFFIX, $CXX, $CXXCOM, $CXXFILESUFFIX, $CXXFLAGS, $INCPREFIX, $INCSUFFIX, $OBJPREFIX, $OBJSUFFIX, $PCHCOM, $PCHPDBFLAGS, $RC, $RCCOM, $RCFLAGS, $SHCC, $SHCCCOM, $SHCCFLAGS, $SHCFLAGS, $SHCXX, $SHCXXCOM, $SHCXXFLAGS, $SHOBJPREFIX, $SHOBJSUFFIX.

    Uses: $CCCOMSTR, $CXXCOMSTR, $MSVC_NOTFOUND_POLICY, $MSVC_SCRIPTERROR_POLICY, $MSVC_SCRIPT_ARGS, $MSVC_SDK_VERSION, $MSVC_SPECTRE_LIBS, $MSVC_TOOLSET_VERSION, $MSVC_USE_SCRIPT, $MSVC_USE_SCRIPT_ARGS, $MSVC_USE_SETTINGS, $MSVC_VERSION, $PCH, $PCHSTOP, $PDB, $SHCCCOMSTR, $SHCXXCOMSTR.

msvs
    Sets construction variables for Microsoft Visual Studio.

    Sets: $MSVSBUILDCOM, $MSVSCLEANCOM, $MSVSENCODING, $MSVSPROJECTCOM, $MSVSREBUILDCOM, $MSVSSCONS, $MSVSSCONSCOM, $MSVSSCONSCRIPT, $MSVSSCONSFLAGS, $MSVSSOLUTIONCOM.

mwcc
    Sets construction variables for the Metrowerks CodeWarrior compiler.

    Sets: $CC, $CCCOM, $CFILESUFFIX, $CPPDEFPREFIX, $CPPDEFSUFFIX, $CXX, $CXXCOM, $CXXFILESUFFIX, $INCPREFIX, $INCSUFFIX, $MWCW_VERSION, $MWCW_VERSIONS, $SHCC, $SHCCCOM, $SHCCFLAGS, $SHCFLAGS, $SHCXX, $SHCXXCOM, $SHCXXFLAGS.

    Uses: $CCCOMSTR, $CXXCOMSTR, $SHCCCOMSTR, $SHCXXCOMSTR.

mwld
    Sets construction variables for the Metrowerks CodeWarrior linker.

    Sets: $AR, $ARCOM, $LIBDIRPREFIX, $LIBDIRSUFFIX, $LIBLINKPREFIX, $LIBLINKSUFFIX, $LINK, $LINKCOM, $SHLINK, $SHLINKCOM, $SHLINKFLAGS.

nasm
    Sets construction variables for the nasm Netwide Assembler.

    Sets: $AS, $ASCOM, $ASFLAGS, $ASPPCOM, $ASPPFLAGS.

    Uses: $ASCOMSTR, $ASPPCOMSTR.

ninja
    Sets up the Ninja builder, which generates a ninja build file, and then optionally runs ninja.

        Note
        This is an experimental feature. This functionality is subject to change and/or removal without a deprecation cycle.

    Sets: $IMPLICIT_COMMAND_DEPENDENCIES, $NINJA_ALIAS_NAME, $NINJA_CMD_ARGS, $NINJA_COMPDB_EXPAND, $NINJA_DEPFILE_PARSE_FORMAT, $NINJA_DIR, $NINJA_DISABLE_AUTO_RUN, $NINJA_ENV_VAR_CACHE, $NINJA_FILE_NAME, $NINJA_FORCE_SCONS_BUILD, $NINJA_GENERATED_SOURCE_ALIAS_NAME, $NINJA_GENERATED_SOURCE_SUFFIXES, $NINJA_MSVC_DEPS_PREFIX, $NINJA_POOL, $NINJA_REGENERATE_DEPS, $NINJA_SCONS_DAEMON_KEEP_ALIVE, $NINJA_SCONS_DAEMON_PORT, $NINJA_SYNTAX, $_NINJA_REGENERATE_DEPS_FUNC.

    Uses: $AR, $ARCOM, $ARFLAGS, $CC, $CCCOM, $CCDEPFLAGS, $CCFLAGS, $CXX, $CXXCOM, $ESCAPE, $LINK, $LINKCOM, $PLATFORM, $PRINT_CMD_LINE_FUNC, $PROGSUFFIX, $RANLIB, $RANLIBCOM, $SHCCCOM, $SHCXXCOM, $SHLINK, $SHLINKCOM.

packaging
    Sets construction variables for the Package Builder. If this tool is enabled, the --package-type command-line option is also enabled.

pdf
    Sets construction variables for the Portable Document Format builder.

    Sets: $PDFPREFIX, $PDFSUFFIX.

pdflatex
    Sets construction variables for the pdflatex utility.

    Sets: $LATEXRETRIES, $PDFLATEX, $PDFLATEXCOM, $PDFLATEXFLAGS.

    Uses: $PDFLATEXCOMSTR.

pdftex
    Sets construction variables for the pdftex utility.

    Sets: $LATEXRETRIES, $PDFLATEX, $PDFLATEXCOM, $PDFLATEXFLAGS, $PDFTEX, $PDFTEXCOM, $PDFTEXFLAGS.

    Uses: $PDFLATEXCOMSTR, $PDFTEXCOMSTR.

python
    Loads the Python source scanner into the invoking environment. When loaded, the scanner will attempt to find implicit dependencies for any Python source files in the list of sources provided to an Action that uses this environment.

    Available since scons 4.0..

qt
    Placeholder tool to alert anyone still using qt tools to switch to qt3 or newer tool.

qt3
    Sets construction variables for building Qt3 applications.

        Note
        This tool is only suitable for building targeted to Qt3, which is obsolete (the tool is deprecated since 4.3, and was renamed to qt3 in 4.5.0. ). There are contributed tools for Qt4 and Qt5, see https://github.com/SCons/scons-contrib[1]. Qt4 has also passed end of life for standard support (in Dec 2015).

    Note paths for these construction variables are assembled using the os.path.join method so they will have the appropriate separator at runtime, but are listed here in the various entries only with the '/' separator for simplicity.

    In addition, the construction variables $CPPPATH, $LIBPATH and $LIBS may be modified and the variables $PROGEMITTER, $SHLIBEMITTER and $LIBEMITTER are modified. Because the build-performance is affected when using this tool, you have to explicitly specify it at Environment creation:

        Environment(tools=['default','qt3'])

    The qt3 tool supports the following operations:

    Automatic moc file generation from header files. You do not have to specify moc files explicitly, the tool does it for you. However, there are a few preconditions to do so: Your header file must have the same filebase as your implementation file and must stay in the same directory. It must have one of the suffixes .h, .hpp, .H, .hxx, .hh. You can turn off automatic moc file generation by setting $QT3_AUTOSCAN to False. See also the corresponding Moc Builder.

    Automatic moc file generation from C++ files. As described in the Qt documentation, include the moc file at the end of the C++ file. Note that you have to include the file, which is generated by the transformation ${QT3_MOCCXXPREFIX}<basename>${QT3_MOCCXXSUFFIX}, by default <basename>.mo. A warning is generated after building the moc file if you do not include the correct file. If you are using VariantDir, you may need to specify duplicate=True. You can turn off automatic moc file generation by setting $QT3_AUTOSCAN to False. See also the corresponding Moc Builder.

    Automatic handling of .ui files. The implementation files generated from .ui files are handled much the same as yacc or lex files. Each .ui file given as a source of Program, Library or SharedLibrary will generate three files: the declaration file, the implementation file and a moc file. Because there are also generated headers, you may need to specify duplicate=True in calls to VariantDir. See also the corresponding Uic Builder.

    Sets: $QT3DIR, $QT3_AUTOSCAN, $QT3_BINPATH, $QT3_CPPPATH, $QT3_LIB, $QT3_LIBPATH, $QT3_MOC, $QT3_MOCCXXPREFIX, $QT3_MOCCXXSUFFIX, $QT3_MOCFROMCXXCOM, $QT3_MOCFROMCXXFLAGS, $QT3_MOCFROMHCOM, $QT3_MOCFROMHFLAGS, $QT3_MOCHPREFIX, $QT3_MOCHSUFFIX, $QT3_UIC, $QT3_UICCOM, $QT3_UICDECLFLAGS, $QT3_UICDECLPREFIX, $QT3_UICDECLSUFFIX, $QT3_UICIMPLFLAGS, $QT3_UICIMPLPREFIX, $QT3_UICIMPLSUFFIX, $QT3_UISUFFIX.

    Uses: $QT3DIR.

rmic
    Sets construction variables for the rmic utility.

    Sets: $JAVACLASSSUFFIX, $RMIC, $RMICCOM, $RMICFLAGS.

    Uses: $RMICCOMSTR.

rpcgen
    Sets construction variables for building with RPCGEN.

    Sets: $RPCGEN, $RPCGENCLIENTFLAGS, $RPCGENFLAGS, $RPCGENHEADERFLAGS, $RPCGENSERVICEFLAGS, $RPCGENXDRFLAGS.

sgiar
    Sets construction variables for the SGI library archiver.

    Sets: $AR, $ARCOMSTR, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX, $SHLINK, $SHLINKFLAGS.

    Uses: $ARCOMSTR, $SHLINKCOMSTR.

sgic++
    Sets construction variables for the SGI C++ compiler.

    Sets: $CXX, $CXXFLAGS, $SHCXX, $SHOBJSUFFIX.

sgicc
    Sets construction variables for the SGI C compiler.

    Sets: $CXX, $SHOBJSUFFIX.

sgilink
    Sets construction variables for the SGI linker.

    Sets: $LINK, $RPATHPREFIX, $RPATHSUFFIX, $SHLINKFLAGS.

sunar
    Sets construction variables for the Sun library archiver.

    Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

    Uses: $ARCOMSTR.

sunc++
    Sets construction variables for the Sun C++ compiler.

    Sets: $CXX, $CXXVERSION, $SHCXX, $SHCXXFLAGS, $SHOBJPREFIX, $SHOBJSUFFIX.

suncc
    Sets construction variables for the Sun C compiler.

    Sets: $CXX, $SHCCFLAGS, $SHOBJPREFIX, $SHOBJSUFFIX.

sunf77
    Set construction variables for the Sun f77 Fortran compiler.

    Sets: $F77, $FORTRAN, $SHF77, $SHF77FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

sunf90
    Set construction variables for the Sun f90 Fortran compiler.

    Sets: $F90, $FORTRAN, $SHF90, $SHF90FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

sunf95
    Set construction variables for the Sun f95 Fortran compiler.

    Sets: $F95, $FORTRAN, $SHF95, $SHF95FLAGS, $SHFORTRAN, $SHFORTRANFLAGS.

sunlink
    Sets construction variables for the Sun linker.

    Sets: $RPATHPREFIX, $RPATHSUFFIX, $SHLINKFLAGS.

swig
    Sets construction variables for the SWIG interface compiler.

    Sets: $SWIG, $SWIGCFILESUFFIX, $SWIGCOM, $SWIGCXXFILESUFFIX, $SWIGDIRECTORSUFFIX, $SWIGFLAGS, $SWIGINCPREFIX, $SWIGINCSUFFIX, $SWIGPATH, $SWIGVERSION, $_SWIGINCFLAGS.

    Uses: $SWIGCOMSTR.

tar
    Sets construction variables for the tar archiver.

    Sets: $TAR, $TARCOM, $TARFLAGS, $TARSUFFIX.

    Uses: $TARCOMSTR.

tex
    Sets construction variables for the TeX formatter and typesetter.

    Sets: $BIBTEX, $BIBTEXCOM, $BIBTEXFLAGS, $LATEX, $LATEXCOM, $LATEXFLAGS, $MAKEINDEX, $MAKEINDEXCOM, $MAKEINDEXFLAGS, $TEX, $TEXCOM, $TEXFLAGS.

    Uses: $BIBTEXCOMSTR, $LATEXCOMSTR, $MAKEINDEXCOMSTR, $TEXCOMSTR.

textfile
    Set construction variables for the Textfile and Substfile builders.

    Sets: $FILE_ENCODING, $LINESEPARATOR, $SUBSTFILEPREFIX, $SUBSTFILESUFFIX, $TEXTFILEPREFIX, $TEXTFILESUFFIX.

    Uses: $SUBST_DICT.

tlib
    Sets construction variables for the Borlan tib library archiver.

    Sets: $AR, $ARCOM, $ARFLAGS, $LIBPREFIX, $LIBSUFFIX.

    Uses: $ARCOMSTR.

xgettext
    This scons tool is a part of scons gettext toolset. It provides scons interface to xgettext(1) program, which extracts internationalized messages from source code. The tool provides POTUpdate builder to make PO Template files.

    Sets: $POTSUFFIX, $POTUPDATE_ALIAS, $XGETTEXTCOM, $XGETTEXTCOMSTR, $XGETTEXTFLAGS, $XGETTEXTFROM, $XGETTEXTFROMPREFIX, $XGETTEXTFROMSUFFIX, $XGETTEXTPATH, $XGETTEXTPATHPREFIX, $XGETTEXTPATHSUFFIX, $_XGETTEXTDOMAIN, $_XGETTEXTFROMFLAGS, $_XGETTEXTPATHFLAGS.

    Uses: $POTDOMAIN.

yacc
    Sets construction variables for the yacc parser generator.

    Sets: $YACC, $YACCCOM, $YACCFLAGS, $YACCHFILESUFFIX, $YACCHXXFILESUFFIX, $YACCVCGFILESUFFIX, $YACC_GRAPH_FILE_SUFFIX.

    Uses: $YACCCOMSTR, $YACCFLAGS, $YACC_GRAPH_FILE, $YACC_HEADER_FILE.

zip
    Sets construction variables for the zip archiver.

    Sets: $ZIP, $ZIPCOM, $ZIPCOMPRESSION, $ZIPFLAGS, $ZIPSUFFIX.

    Uses: $ZIPCOMSTR.

  Builder Methods

You tell SCons what to build by calling Builders, functions which take particular action(s) to produce target(s) of a particular type (conventionally hinted at by the builder name, e.g. Program) from the specified source files. A builder call is a declaration: SCons enters the specified relationship into its internal dependency node graph, and only later makes the decision on whether anything is actually built, since this depends on command-line options, target selection rules, and whether the target(s) are out of date with respect to the sources.

SCons provides a number of builders, and you can also write your own (see Builder Objects). Builders are created dynamically at run-time, often (though not always) by tools which determine whether the external dependencies for the builder are satisfied, and which perform the necessary setup (see Tools). Builders are attached to a construction environment as methods. The available builder methods are registered as key-value pairs in the $BUILDERS attribute of the construction environment, so the available builders can be examined. This example displays them for debugging purposes:

    env = Environment()
    print("Builders:", list(env['BUILDERS']))

Builder methods take two required arguments: target and source. The target and source arguments can be specified either as positional arguments, in which case target comes first, or as keyword arguments, using target= and source=. Although both arguments are nominally required, if there is a single source and the target can be inferred the target argument can be omitted (see below). Builder methods also take a variety of keyword arguments, described below.

Because long lists of file names can lead to a lot of quoting in a builder call, SCons supplies a Split global function and a same-named environment method that splits a single string into a list, using strings of white-space characters as the delimiter (similar to the Python string split method, but succeeds even if the input isn't a string).

The following are equivalent examples of calling the Program builder method:

    env.Program('bar', ['bar.c', 'foo.c'])
    env.Program('bar', Split('bar.c foo.c'))
    env.Program('bar', env.Split('bar.c foo.c'))
    env.Program(source=['bar.c', 'foo.c'], target='bar')
    env.Program(target='bar', source=Split('bar.c foo.c'))
    env.Program(target='bar', source=env.Split('bar.c foo.c'))
    env.Program('bar', source='bar.c foo.c'.split())

Sources and targets can be specified as a scalar or as a list, composed of either strings or nodes (more on nodes below). When specifying path strings, Python follows the POSIX pathname convention: if a string begins with the operating system pathname separator (on Windows both the slash and backslash separator are accepted, and any leading drive specifier is ignored for the determination) it is considered an absolute path, otherwise it is a relative path. If the path string contains no separator characters, it is searched for as a file in the current directory. If it contains separator characters, the search follows down from the starting point, which is the top of the directory tree for an absolute path and the current directory for a relative path. The "current directory" in this context is the directory of the SConscript file currently being processed.

SCons also recognizes a third way to specify path strings: if the string begins with the # character it is top-relative - it works like a relative path but the search follows down from the project top directory rather than from the current directory. The # can optionally be followed by a pathname separator, which is ignored if found in that position. Top-relative paths only work in places where scons will interpret the path (see some examples below). To be used in other contexts the string will need to be converted to a relative or absolute path first.

Examples:

    # The comments describing the targets that will be built
    # assume these calls are in a SConscript file in the
    # a subdirectory named "subdir".
    # Builds the program "subdir/foo" from "subdir/foo.c":
    env.Program('foo', 'foo.c')
    # Builds the program "/tmp/bar" from "subdir/bar.c":
    env.Program('/tmp/bar', 'bar.c')
    # An initial '#' or '#/' are equivalent; the following
    # calls build the programs "foo" and "bar" (in the
    # top-level SConstruct directory) from "subdir/foo.c" and
    # "subdir/bar.c", respectively:
    env.Program('#foo', 'foo.c')
    env.Program('#/bar', 'bar.c')
    # Builds the program "other/foo" (relative to the top-level
    # SConstruct directory) from "subdir/foo.c":
    env.Program('#other/foo', 'foo.c')
    # This will not work, only SCons interfaces understand '#',
    # os.path.exists is pure Python:
    if os.path.exists('#inc/foo.h'):
        env.Append(CPPPATH='#inc')

When the target shares the same base name as the source and only the suffix varies, and if the builder method has a suffix defined for the target file type, then the target argument may be omitted completely, and scons will deduce the target file name from the source file name. The following examples all build the executable program bar (on POSIX systems) or bar.exe (on Windows systems) from the bar.c source file:

    env.Program(target='bar', source='bar.c')
    env.Program('bar', source='bar.c')
    env.Program(source='bar.c')
    env.Program('bar.c')

The optional srcdir keyword argument specifies that all source file strings that are not absolute paths or top-relative paths shall be interpreted relative to the specified srcdir. The following example will build the build/prog (or build/prog.exe on Windows) program from the files src/f1.c and src/f2.c:

    env.Program('build/prog', ['f1.c', 'f2.c'], srcdir='src')

The optional parse_flags keyword argument causes behavior similar to the env.MergeFlags method, where the argument value is broken into individual settings and merged into the appropriate construction variables.

    env.Program('hello', 'hello.c', parse_flags='-Iinclude -DEBUG -lm')

This example adds 'include' to the $CPPPATH construction variable, 'EBUG' to $CPPDEFINES, and 'm' to $LIBS.

The optional chdir keyword argument specifies that the Builder's action(s) should be executed after changing directory. If the chdir argument is a path string or a directory Node, scons will change to the specified directory. If the chdir is not a string or Node and evaluates true, then scons will change to the target file's directory.

    Warning

    Python only keeps one current directory location even if there are multiple threads. This means that use of the chdir argument will not work with the SCons -j option, because individual worker threads spawned by SCons interfere with each other when they start changing directory.

        # scons will change to the "sub" subdirectory
        # before executing the "cp" command.
        env.Command(
            target='sub/dir/foo.out',
            source='sub/dir/foo.in',
            action="cp dir/foo.in dir/foo.out",
            chdir='sub',
        )
        # Because chdir is not a string, scons will change to the
        # target's directory ("sub/dir") before executing the
        # "cp" command.
        env.Command('sub/dir/foo.out', 'sub/dir/foo.in', "cp foo.in foo.out", chdir=True)

Note that SCons will not automatically modify its expansion of construction variables like $TARGET and $SOURCE when using the chdir keyword argument--that is, the expanded file names will still be relative to the project top directory, and consequently incorrect relative to the chdir directory. If you use the chdir keyword argument, you will typically need to supply a different command line using expansions like ${TARGET.file} and ${SOURCE.file} to use just the filename portion of the target and source.

Keyword arguments that are not specifically recognized are treated as construction variable overrides, which replace or add those variables on a limited basis. These overrides will only be in effect when building the target of the builder call, and will not affect other parts of the build. For example, if you want to specify some libraries needed by just one program:

    env.Program('hello', 'hello.c', LIBS=['gl', 'glut'])

or generate a shared library with a non-standard suffix:

    env.SharedLibrary(
        target='word',
        source='word.cpp',
        SHLIBSUFFIX='.ocx',
        LIBSUFFIXES=['.ocx'],
    )

Note that both the $SHLIBSUFFIX and $LIBSUFFIXES construction variables must be set if you want scons to search automatically for dependencies on the non-standard library names; see the descriptions of these variables for more information.

Although the builder methods defined by scons are, in fact, methods of a construction environment object, many may also be called without an explicit environment:

    Program('hello', 'hello.c')
    SharedLibrary('word', 'word.cpp')

If called this way, the builder will internally use the Default Environment that consists of the tools and values that scons has determined are appropriate for the local system.

Builder methods that can be called without an explicit environment (indicated in the listing of builders below without a leading env.) may be called from custom Python modules that you import into an SConscript file by adding the following to the Python module:

    from SCons.Script import *

A builder may add additional targets beyond those requested if an attached Emitter chooses to do so (see the section called “Builder Objects” for more information. $PROGEMITTER is an example). For example, the GNU linker takes a command-line argument -Map=mapfile, which causes it to produce a linker map file in addition to the executable file actually being linked. If the Program builder's emitter is configured to add this mapfile if the option is set, then two targets will be returned when you only provided for one.

For this reason, builder methods always return a NodeList, a list-like object whose elements are Nodes. Nodes are the internal representation of build targets or sources (see the section called “Node Objects” for more information). The returned NodeList object can be passed to other builder methods as source(s) or to other SCons functions or methods where a path string would normally be accepted.

For example, to add a specific preprocessor define when compiling one specific object file but not the others:

    bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
    env.Program("prog", ['foo.c', bar_obj_list, 'main.c'])

Using a Node as in this example makes for a more portable build by avoiding having to specify a platform-specific object suffix when calling the Program builder method.

The NodeList object is also convenient to pass to the Default function, for the same reason of avoiding a platform-specific name:

    tgt = env.Program("prog", ["foo.c", "bar.c", "main.c"])
    Default(tgt)

Builder calls will automatically "flatten" lists passed as source and target, so they are free to contain elements which are themselves lists, such as bar_obj_list returned by the StaticObject call. If you need to manipulate a list of lists returned by builders directly in Python code, you can either build a new list by hand:

    foo = Object('foo.c')
    bar = Object('bar.c')
    objects = ['begin.o'] + foo + ['middle.o'] + bar + ['end.o']
    for obj in objects:
        print(str(obj))

Or you can use the Flatten function supplied by SCons to create a list containing just the Nodes, which may be more convenient:

    foo = Object('foo.c')
    bar = Object('bar.c')
    objects = Flatten(['begin.o', foo, 'middle.o', bar, 'end.o'])
    for obj in objects:
        print(str(obj))

Since builder calls return a list-like object, not an actual Python list, it is not appropriate to use the Python add operator (+ or +=) to append builder results to a Python list. Because the list and the object are different types, Python will not update the original list in place, but will instead create a new NodeList object containing the concatenation of the list elements and the builder results. This will cause problems for any other Python variables in your SCons configuration that still hold on to a reference to the original list. Instead, use the Python list extend method to make sure the list is updated in-place. Example:

    object_files = []
    # Do NOT use += here:
    #    object_files += Object('bar.c')
    #
    # It will not update the object_files list in place.
    #
    # Instead, use the list extend method:
    object_files.extend(Object('bar.c'))

The path name for a Node's file may be used by passing the Node to Python's builtin str function:

    bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
    print("The path to bar_obj is:", str(bar_obj_list[0]))

Note that because the Builder call returns a NodeList, you have to access the first element in the list (bar_obj_list[0] in the example) to get at the Node that actually represents the object file.

When trying to handle errors that may occur in a builder method, consider that the corresponding Action is executed at a different time than the SConscript file statement calling the builder. It is not useful to wrap a builder call in a try block, since success in the builder call is not the same as the builder itself succeeding. If necessary, a Builder's Action should be coded to exit with a useful exception message indicating the problem in the SConscript files - programmatically recovering from build errors is rarely useful.

The following builder methods are predefined in the SCons core software distribution. Depending on the setup of a particular construction environment and on the type and software installation status of the underlying system, not all builders may be available in that construction environment. Since the function calling signature is the same for all builders:

    Buildername(target, source, [key=val, ...])

it is omitted in this listing for brevity.

CFile(), env.CFile()
    Builds a C source file given a lex (.l) or yacc (.y) input file. The suffix specified by the $CFILESUFFIX construction variable (.c by default) is automatically added to the target if it is not already present. Example:

        # builds foo.c
        env.CFile(target='foo.c', source='foo.l')
        # builds bar.c
        env.CFile(target='bar', source='bar.y')

Command(), env.Command()
    There is actually no Builder named Command, rather the term "Command Builder" refers to a function which, on each call, creates and calls an anonymous Builder. This is useful for "one-off" builds where a full Builder is not needed. Since the anonymous Builder is never hooked into the standard Builder framework, an Action must always be specfied. See the Command function description for the calling syntax and details.

CompilationDatabase(), env.CompilationDatabase()
    CompilationDatabase is a special builder which adds a target to create a JSON formatted compilation database compatible with clang tooling (see the LLVM specification[2]). This database is suitable for consumption by various tools and editors who can use it to obtain build and dependency information which otherwise would be internal to SCons. The builder does not require any source files to be specified, rather it arranges to emit information about all of the C, C++ and assembler source/output pairs identified in the build that are not excluded by the optional filter $COMPILATIONDB_PATH_FILTER. The target is subject to the usual SCons target selection rules.

    If called with no arguments, the builder will default to a target name of compile_commands.json.

    If called with a single positional argument, scons will "deduce" the target name from that source argument, giving it the same name, and then ignore the source. This is the usual way to call the builder if a non-default target name is wanted.

    If called with either the target= or source= keyword arguments, the value of the argument is taken as the target name. If called with both, the target= value is used and source= is ignored. If called with multiple sources, the source list will be ignored, since there is no way to deduce what the intent was; in this case the default target name will be used.

        Note
        You must load the compilation_db tool prior to specifying any part of your build or some source/output files will not show up in the compilation database.

    Available since scons 4.0.

CXXFile(), env.CXXFile()
    Builds a C++ source file given a lex (.ll) or yacc (.yy) input file. The suffix specified by the $CXXFILESUFFIX construction variable (.cc by default) is automatically added to the target if it is not already present. Example:

        # builds foo.cc
        env.CXXFile(target='foo.cc', source='foo.ll')
        # builds bar.cc
        env.CXXFile(target='bar', source='bar.yy')

DocbookEpub(), env.DocbookEpub()
    A pseudo-Builder, providing a Docbook toolchain for EPUB output.

        env = Environment(tools=['docbook'])
        env.DocbookEpub('manual.epub', 'manual.xml')

    or simply

        env = Environment(tools=['docbook'])
        env.DocbookEpub('manual')

DocbookHtml(), env.DocbookHtml()
    A pseudo-Builder, providing a Docbook toolchain for HTML output.

        env = Environment(tools=['docbook'])
        env.DocbookHtml('manual.html', 'manual.xml')

    or simply

        env = Environment(tools=['docbook'])
        env.DocbookHtml('manual')

DocbookHtmlChunked(), env.DocbookHtmlChunked()
    A pseudo-Builder providing a Docbook toolchain for chunked HTML output. It supports the base.dir parameter. The chunkfast.xsl file (requires "EXSLT") is used as the default stylesheet. Basic syntax:

        env = Environment(tools=['docbook'])
        env.DocbookHtmlChunked('manual')

    where manual.xml is the input file.

    If you use the root.filename parameter in your own stylesheets you have to specify the new target name. This ensures that the dependencies get correct, especially for the cleanup via “scons -c”:

        env = Environment(tools=['docbook'])
        env.DocbookHtmlChunked('mymanual.html', 'manual', xsl='htmlchunk.xsl')

    Some basic support for the base.dir parameter is provided. You can add the base_dir keyword to your Builder call, and the given prefix gets prepended to all the created filenames:

        env = Environment(tools=['docbook'])
        env.DocbookHtmlChunked('manual', xsl='htmlchunk.xsl', base_dir='output/')

    Make sure that you don't forget the trailing slash for the base folder, else your files get renamed only!

DocbookHtmlhelp(), env.DocbookHtmlhelp()
    A pseudo-Builder, providing a Docbook toolchain for HTMLHELP output. Its basic syntax is:

        env = Environment(tools=['docbook'])
        env.DocbookHtmlhelp('manual')

    where manual.xml is the input file.

    If you use the root.filename parameter in your own stylesheets you have to specify the new target name. This ensures that the dependencies get correct, especially for the cleanup via “scons -c”:

        env = Environment(tools=['docbook'])
        env.DocbookHtmlhelp('mymanual.html', 'manual', xsl='htmlhelp.xsl')

    Some basic support for the base.dir parameter is provided. You can add the base_dir keyword to your Builder call, and the given prefix gets prepended to all the created filenames:

        env = Environment(tools=['docbook'])
        env.DocbookHtmlhelp('manual', xsl='htmlhelp.xsl', base_dir='output/')

    Make sure that you don't forget the trailing slash for the base folder, else your files get renamed only!

DocbookMan(), env.DocbookMan()
    A pseudo-Builder, providing a Docbook toolchain for Man page output. Its basic syntax is:

        env = Environment(tools=['docbook'])
        env.DocbookMan('manual')

    where manual.xml is the input file. Note, that you can specify a target name, but the actual output names are automatically set from the refname entries in your XML source.

DocbookPdf(), env.DocbookPdf()
    A pseudo-Builder, providing a Docbook toolchain for PDF output.

        env = Environment(tools=['docbook'])
        env.DocbookPdf('manual.pdf', 'manual.xml')

    or simply

        env = Environment(tools=['docbook'])
        env.DocbookPdf('manual')

DocbookSlidesHtml(), env.DocbookSlidesHtml()
    A pseudo-Builder, providing a Docbook toolchain for HTML slides output.

        env = Environment(tools=['docbook'])
        env.DocbookSlidesHtml('manual')

    If you use the titlefoil.html parameter in your own stylesheets you have to give the new target name. This ensures that the dependencies get correct, especially for the cleanup via “scons -c”:

        env = Environment(tools=['docbook'])
        env.DocbookSlidesHtml('mymanual.html','manual', xsl='slideshtml.xsl')

    Some basic support for the base.dir parameter is provided. You can add the base_dir keyword to your Builder call, and the given prefix gets prepended to all the created filenames:

        env = Environment(tools=['docbook'])
        env.DocbookSlidesHtml('manual', xsl='slideshtml.xsl', base_dir='output/')

    Make sure that you don't forget the trailing slash for the base folder, else your files get renamed only!

DocbookSlidesPdf(), env.DocbookSlidesPdf()
    A pseudo-Builder, providing a Docbook toolchain for PDF slides output.

        env = Environment(tools=['docbook'])
        env.DocbookSlidesPdf('manual.pdf', 'manual.xml')

    or simply

        env = Environment(tools=['docbook'])
        env.DocbookSlidesPdf('manual')

DocbookXInclude(), env.DocbookXInclude()
    A pseudo-Builder, for resolving XIncludes in a separate processing step.

        env = Environment(tools=['docbook'])
        env.DocbookXInclude('manual_xincluded.xml', 'manual.xml')

DocbookXslt(), env.DocbookXslt()
    A pseudo-Builder, applying a given XSL transformation to the input file.

        env = Environment(tools=['docbook'])
        env.DocbookXslt('manual_transformed.xml', 'manual.xml', xsl='transform.xslt')

    Note, that this builder requires the xsl parameter to be set.

DVI(), env.DVI()
    Builds a .dvi file from a .tex, .ltx or .latex input file. If the source file suffix is .tex, scons will examine the contents of the file; if the string \documentclass or \documentstyle is found, the file is assumed to be a LaTeX file and the target is built by invoking the $LATEXCOM command line; otherwise, the $TEXCOM command line is used. If the file is a LaTeX file, the DVI builder method will also examine the contents of the .aux file and invoke the $BIBTEX command line if the string bibdata is found, start $MAKEINDEX to generate an index if a .ind file is found and will examine the contents .log file and re-run the $LATEXCOM command if the log file says it is necessary.

    The suffix .dvi (hard-coded within TeX itself) is automatically added to the target if it is not already present. Examples:

        # builds from aaa.tex
        env.DVI(target = 'aaa.dvi', source = 'aaa.tex')
        # builds bbb.dvi
        env.DVI(target = 'bbb', source = 'bbb.ltx')
        # builds from ccc.latex
        env.DVI(target = 'ccc.dvi', source = 'ccc.latex')

Gs(), env.Gs()
    A Builder for explicitly calling the gs executable. Depending on the underlying OS, the different names gs, gsos2 and gswin32c are tried.

        env = Environment(tools=['gs'])
        env.Gs(
            'cover.jpg',
            'scons-scons.pdf',
            GSFLAGS='-dNOPAUSE -dBATCH -sDEVICE=jpeg -dFirstPage=1 -dLastPage=1 -q',
        )

Install(), env.Install()
    Installs one or more source files or directories in the specified target, which must be a directory. The names of the specified source files or directories remain the same within the destination directory. The sources may be given as a string or as a node returned by a builder.

        env.Install(target='/usr/local/bin', source=['foo', 'bar'])

    Note that if target paths chosen for the Install builder (and the related InstallAs and InstallVersionedLib builders) are outside the project tree, such as in the example above, they may not be selected for "building" by default, since in the absence of other instructions scons builds targets that are underneath the top directory (the directory that contains the SConstruct file, usually the current directory). Use command line targets or the Default function in this case.

    If the --install-sandbox command line option is given, the target directory will be prefixed by the directory path specified. This is useful to test installs without installing to a "live" location in the system.

    See also FindInstalledFiles. For more thoughts on installation, see the User Guide (particularly the section on Command-Line Targets and the chapters on Installing Files and on Alias Targets).

InstallAs(), env.InstallAs()
    Installs one or more source files or directories to specific names, allowing changing a file or directory name as part of the installation. It is an error if the target and source arguments list different numbers of files or directories.

        env.InstallAs(target='/usr/local/bin/foo',
                      source='foo_debug')
        env.InstallAs(target=['../lib/libfoo.a', '../lib/libbar.a'],
                      source=['libFOO.a', 'libBAR.a'])

    See the note under Install.

InstallVersionedLib(), env.InstallVersionedLib()
    Installs a versioned shared library. The symlinks appropriate to the architecture will be generated based on symlinks of the source library.

        env.InstallVersionedLib(target='/usr/local/bin/foo',
                                source='libxyz.1.5.2.so')

    See the note under Install.

Jar(), env.Jar()
    Builds a Java archive (.jar) file from the specified list of sources. Any directories in the source list will be searched for .class files). Any .java files in the source list will be compiled to .class files by calling the Java Builder.

    If the $JARCHDIR value is set, the jar command will change to the specified directory using the -C option. If $JARCHDIR is not set explicitly, SCons will use the top of any subdirectory tree in which Java .class were built by the Java Builder.

    If the contents any of the source files begin with the string Manifest-Version, the file is assumed to be a manifest and is passed to the jar command with the m option set.

        env.Jar(target = 'foo.jar', source = 'classes')
        env.Jar(target = 'bar.jar',
                source = ['bar1.java', 'bar2.java'])

Java(), env.Java()
    Builds one or more Java class files. The sources may be any combination of explicit .java files, or directory trees which will be scanned for .java files.

    SCons will parse each source .java file to find the classes (including inner classes) defined within that file, and from that figure out the target .class files that will be created. The class files will be placed underneath the specified target directory.

    SCons will also search each Java file for the Java package name, which it assumes can be found on a line beginning with the string package in the first column; the resulting .class files will be placed in a directory reflecting the specified package name. For example, the file Foo.java defining a single public Foo class and containing a package name of sub.dir will generate a corresponding sub/dir/Foo.class class file.

    Examples:

        env.Java(target='classes', source='src')
        env.Java(target='classes', source=['src1', 'src2'])
        env.Java(target='classes', source=['File1.java', 'File2.java'])

    Java source files can use the native encoding for the underlying OS. Since SCons compiles in simple ASCII mode by default, the compiler will generate warnings about unmappable characters, which may lead to errors as the file is processed further. In this case, the user must specify the LANG environment variable to tell the compiler what encoding is used. For portibility, it's best if the encoding is hard-coded so that the compile will work if it is done on a system with a different encoding.

        env = Environment()
        env['ENV']['LANG'] = 'en_GB.UTF-8'

JavaH(), env.JavaH()
    Builds C header and source files for implementing Java native methods. The target can be either a directory in which the header files will be written, or a header file name which will contain all of the definitions. The source can be the names of .class files, the names of .java files to be compiled into .class files by calling the Java builder method, or the objects returned from the Java builder method.

    If the construction variable $JAVACLASSDIR is set, either in the environment or in the call to the JavaH builder method itself, then the value of the variable will be stripped from the beginning of any .class file names.

    Examples:

        # builds java_native.h
        classes = env.Java(target="classdir", source="src")
        env.JavaH(target="java_native.h", source=classes)
        # builds include/package_foo.h and include/package_bar.h
        env.JavaH(target="include", source=["package/foo.class", "package/bar.class"])
        # builds export/foo.h and export/bar.h
        env.JavaH(
            target="export",
            source=["classes/foo.class", "classes/bar.class"],
            JAVACLASSDIR="classes",
        )

        Note
        Java versions starting with 10.0 no longer use the javah command for generating JNI headers/sources, and indeed have removed the command entirely (see Java Enhancement Proposal JEP 313[3]), making this tool harder to use for that purpose. SCons may autodiscover a javah belonging to an older release if there are multiple Java versions on the system, which will lead to incorrect results. To use with a newer Java, override the default values of $JAVAH (to contain the path to the javac) and $JAVAHFLAGS (to contain at least a -h flag) and note that generating headers with javac requires supplying source .java files only, not .class files.

Library(), env.Library()
    A synonym for the StaticLibrary builder method.

LoadableModule(), env.LoadableModule()
    On most systems, this is the same as SharedLibrary. On Mac OS X (Darwin) platforms, this creates a loadable module bundle.

M4(), env.M4()
    Builds an output file from an M4 input file. This uses a default $M4FLAGS value of -E, which considers all warnings to be fatal and stops on the first warning when using the GNU version of m4. Example:

        env.M4(target = 'foo.c', source = 'foo.c.m4')

Moc(), env.Moc()
    Builds an output file from a moc input file. moc input files are either header files or C++ files. This builder is only available after using the tool qt3. See the $QT3DIR variable for more information. Example:

        env.Moc('foo.h')  # generates moc_foo.cc
        env.Moc('foo.cpp')  # generates foo.moc

MOFiles(), env.MOFiles()
    This builder belongs to msgfmt tool. The builder compiles PO files to MO files.

    Example 1. Create pl.mo and en.mo by compiling pl.po and en.po:

          # ...
          env.MOFiles(['pl', 'en'])

    Example 2. Compile files for languages defined in LINGUAS file:

          # ...
          env.MOFiles(LINGUAS_FILE = 1)

    Example 3. Create pl.mo and en.mo by compiling pl.po and en.po plus files for languages defined in LINGUAS file:

          # ...
          env.MOFiles(['pl', 'en'], LINGUAS_FILE = 1)

    Example 4. Compile files for languages defined in LINGUAS file (another version):

          # ...
          env['LINGUAS_FILE'] = 1
          env.MOFiles()

MSVSProject(), env.MSVSProject()
    Build a Microsoft Visual C++ project file and solution file.

    Builds a Microsoft Visual C++ project file based on the version of Visual Studio (or to be more precise, of MSBuild) that is configured: either the latest installed version, or the version specified by $MSVC_VERSION in the current construction environment. For Visual Studio 6.0 a .dsp file is generated. For Visual Studio versions 2002-2008, a .vcproj file is generated. For Visual Studio 2010 and later a .vcxproj file is generated. Note there are multiple versioning schemes involved in the Microsoft compilation environment - see the description of $MSVC_VERSION for equivalences. Note SCons does not know how to construct project files for other languages (e.g. .csproj for C#, .vbproj for Visual Basic or .pyproject for Python).

    For the .vcxproj file, the underlying format is the MSBuild XML Schema, and the details conform to: https://learn.microsoft.com/en-us/cpp/build/reference/vcxproj-file-structure[4]. The generated solution file enables Visual Studio to understand the project structure, and allows building it using MSBuild to call back to SCons. The project file encodes a toolset version that has been selected by SCons as described above. Since recent Visual Studio versions support multiple concurrent toolsets, use $MSVC_VERSION to select the desired one if it does not match the SCons default. The project file also includes entries which describe how to call SCons to build the project from within Visual Studio (or from an MSBuild command line). In some situations SCons may generate this incorrectly - notably when using the scons-local distribution, which is not installed in a way that that matches the default invocation line. If so, the $SCONS_HOME construction variable can be used to describe the right way to locate the SCons code so that it can be imported.

    By default, a matching solution file for the project is also generated. This behavior may be disabled by specifying auto_build_solution=0 to the MSVSProject builder. The solution file can also be independently generated by calling the MSVSSolution builder, such as in the case where a solution should describe multiple projects. See the MSVSSolution description for further information.

    The MSVSProject builder accepts several keyword arguments describing lists of filenames to be placed into the project file. Currently, srcs, incs, localincs, resources, and misc are recognized. The names are intended to be self-explanatory, but note that the filenames need to be specified as strings, not as SCons File Nodes (for example if you generate files for inclusion by using the Glob function, the results should be converted to a list of strings before passing them to MSVSProject). This is because Visual Studio and MSBuild know nothing about SCons Node types. Each of the filename lists are individually optional, but at least one list must be specified for the resulting project file to be non-empty.

    In addition to the above lists of values, the following values may be specified as keyword arguments:

    target
        The name of the target .dsp or .vcproj file. The correct suffix for the version of Visual Studio must be used, but the $MSVSPROJECTSUFFIX construction variable will be defined to the correct value (see example below).

    variant
        The name of this particular variant. Except for Visual Studio 6 projects, this can also be a list of variant names. These are typically things like "Debug" or "Release", but really can be anything you want. For Visual Studio 7 projects, they may also specify a target platform separated from the variant name by a | (vertical pipe) character: Debug|Xbox. The default target platform is Win32. Multiple calls to MSVSProject with different variants are allowed; all variants will be added to the project file with their appropriate build targets and sources.

    cmdargs
        Additional command line arguments for the different variants. The number of cmdargs entries must match the number of variant entries, or be empty (not specified). If you give only one, it will automatically be propagated to all variants.

    cppdefines
        Preprocessor definitions for the different variants. The number of cppdefines entries must match the number of variant entries, or be empty (not specified). If you give only one, it will automatically be propagated to all variants. If you don't give this parameter, SCons will use the invoking environment's $CPPDEFINES entry for all variants.

    cppflags
        Compiler flags for the different variants. If a /std:c++ flag is found then /Zc:__cplusplus is appended to the flags if not already found, this ensures that Intellisense uses the /std:c++ switch. The number of cppflags entries must match the number of variant entries, or be empty (not specified). If you give only one, it will automatically be propagated to all variants. If you don't give this parameter, SCons will combine the invoking environment's $CCFLAGS, $CXXFLAGS, $CPPFLAGS entries for all variants.

    cpppaths
        Compiler include paths for the different variants. The number of cpppaths entries must match the number of variant entries, or be empty (not specified). If you give only one, it will automatically be propagated to all variants. If you don't give this parameter, SCons will use the invoking environment's $CPPPATH entry for all variants.

    buildtarget
        An optional string, node, or list of strings or nodes (one per build variant), to tell the Visual Studio debugger what output target to use in what build variant. The number of buildtarget entries must match the number of variant entries.

    runfile
        The name of the file that Visual Studio 7 and later will run and debug. This appears as the value of the Output field in the resulting Microsoft Visual C++ project file. If this is not specified, the default is the same as the specified buildtarget value.

        Note
        SCons and Microsoft Visual Studio understand projects in different ways, and the mapping is sometimes imperfect:

        Because SCons always executes its build commands from the directory in which the SConstruct file is located, if you generate a project file in a different directory than the directory of the SConstruct file, users will not be able to double-click on the file name in compilation error messages displayed in the Visual Studio console output window. This can be remedied by adding the Microsoft Visual C++ /FC compiler option to the $CCFLAGS variable so that the compiler will print the full path name of any files that cause compilation errors.

        If the project file is only used to teach the Visual Studio project browser about the file layout there should be no issues, However, Visual Studio should not be used to make changes to the project structure, build options, etc. as these will (a) not feed back to the SCons description of the project and (b) be lost if SCons regenerates the project file. The SConscript files should remain the definitive description of the build.

        If the project file is used to drive MSBuild (such as selecting "build" from the Visual Studio interface) you lose the direct control of target selection and command-line options you would have if launching the build directly from SCons, because these will be hardcoded in the project file to the values specified in the MSVSProject call. You can regain some of this control by defining multiple variants, using multiple MSVSProject calls to arrange different build targets, arguments, defines, flags and paths for different variants.

        If the build is divided into a solution with multiple MSBuild projects the mapping is further strained. In this case, it is important not to set Visual Studio to do parallel builds, as it will then launch the separate project builds in parallel, and SCons does not work well if called that way. Instead you can set up the SCons build for parallel building - see the SetOption function for how to do this with num_jobs.

    Example usage:

        barsrcs = ['bar.cpp']
        barincs = ['bar.h']
        barlocalincs = ['StdAfx.h']
        barresources = ['bar.rc', 'resource.h']
        barmisc = ['bar_readme.txt']
        dll = env.SharedLibrary(target='bar.dll', source=barsrcs)
        buildtarget = [s for s in dll if str(s).endswith('dll')]
        env.MSVSProject(
            target='Bar' + env['MSVSPROJECTSUFFIX'],
            srcs=barsrcs,
            incs=barincs,
            localincs=barlocalincs,
            resources=barresources,
            misc=barmisc,
            buildtarget=buildtarget,
            variant='Release',
        )

    DebugSettings
        A dictionary of debug settings that get written to the .vcproj.user or the .vcxproj.user file, depending on the version installed. As for cmdargs, you can specify a DebugSettings dictionary per variant. If you give only one, it will be propagated to all variants.

        Changed in version 2.4: Added the optional DebugSettings parameter.

    Currently, only Visual Studio v9.0 and Visual Studio version v11 are implemented, for other versions no file is generated. To generate the user file, you just need to add a DebugSettings dictionary to the environment with the right parameters for your MSVS version. If the dictionary is empty, or does not contain any good value, no file will be generated.

    Following is a more contrived example, involving the setup of a project for variants and DebugSettings:

        # Assuming you store your defaults in a file
        vars = Variables('variables.py')
        msvcver = vars.args.get('vc', '9')
        # Check command args to force one Microsoft Visual Studio version
        if msvcver == '9' or msvcver == '11':
            env = Environment(MSVC_VERSION=msvcver + '.0', MSVC_BATCH=False)
        else:
            env = Environment()
        AddOption(
            '--userfile',
            action='store_true',
            dest='userfile',
            default=False,
            help="Create Visual C++ project file",
        )
        #
        # 1. Configure your Debug Setting dictionary with options you want in the list
        # of allowed options, for instance if you want to create a user file to launch
        # a specific application for testing your dll with Microsoft Visual Studio 2008 (v9):
        #
        V9DebugSettings = {
            'Command': 'c:\\myapp\\using\\thisdll.exe',
            'WorkingDirectory': 'c:\\myapp\\using\\',
            'CommandArguments': '-p password',
            # 'Attach':'false',
            # 'DebuggerType':'3',
            # 'Remote':'1',
            # 'RemoteMachine': None,
            # 'RemoteCommand': None,
            # 'HttpUrl': None,
            # 'PDBPath': None,
            # 'SQLDebugging': None,
            # 'Environment': '',
            # 'EnvironmentMerge':'true',
            # 'DebuggerFlavor': None,
            # 'MPIRunCommand': None,
            # 'MPIRunArguments': None,
            # 'MPIRunWorkingDirectory': None,
            # 'ApplicationCommand': None,
            # 'ApplicationArguments': None,
            # 'ShimCommand': None,
            # 'MPIAcceptMode': None,
            # 'MPIAcceptFilter': None,
        }
        #
        # 2. Because there are a lot of different options depending on the Microsoft
        # Visual Studio version, if you use more than one version you have to
        # define a dictionary per version, for instance if you want to create a user
        # file to launch a specific application for testing your dll with Microsoft
        # Visual Studio 2012 (v11):
        #
        V10DebugSettings = {
            'LocalDebuggerCommand': 'c:\\myapp\\using\\thisdll.exe',
            'LocalDebuggerWorkingDirectory': 'c:\\myapp\\using\\',
            'LocalDebuggerCommandArguments': '-p password',
            # 'LocalDebuggerEnvironment': None,
            # 'DebuggerFlavor': 'WindowsLocalDebugger',
            # 'LocalDebuggerAttach': None,
            # 'LocalDebuggerDebuggerType': None,
            # 'LocalDebuggerMergeEnvironment': None,
            # 'LocalDebuggerSQLDebugging': None,
            # 'RemoteDebuggerCommand': None,
            # 'RemoteDebuggerCommandArguments': None,
            # 'RemoteDebuggerWorkingDirectory': None,
            # 'RemoteDebuggerServerName': None,
            # 'RemoteDebuggerConnection': None,
            # 'RemoteDebuggerDebuggerType': None,
            # 'RemoteDebuggerAttach': None,
            # 'RemoteDebuggerSQLDebugging': None,
            # 'DeploymentDirectory': None,
            # 'AdditionalFiles': None,
            # 'RemoteDebuggerDeployDebugCppRuntime': None,
            # 'WebBrowserDebuggerHttpUrl': None,
            # 'WebBrowserDebuggerDebuggerType': None,
            # 'WebServiceDebuggerHttpUrl': None,
            # 'WebServiceDebuggerDebuggerType': None,
            # 'WebServiceDebuggerSQLDebugging': None,
        }
        #
        # 3. Select the dictionary you want depending on the version of visual Studio
        # Files you want to generate.
        #
        if not env.GetOption('userfile'):
            dbgSettings = None
        elif env.get('MSVC_VERSION', None) == '9.0':
            dbgSettings = V9DebugSettings
        elif env.get('MSVC_VERSION', None) == '11.0':
            dbgSettings = V10DebugSettings
        else:
            dbgSettings = None
        #
        # 4. Add the dictionary to the DebugSettings keyword.
        #
        barsrcs = ['bar.cpp', 'dllmain.cpp', 'stdafx.cpp']
        barincs = ['targetver.h']
        barlocalincs = ['StdAfx.h']
        barresources = ['bar.rc', 'resource.h']
        barmisc = ['ReadMe.txt']
        dll = env.SharedLibrary(target='bar.dll', source=barsrcs)
        env.MSVSProject(
            target='Bar' + env['MSVSPROJECTSUFFIX'],
            srcs=barsrcs,
            incs=barincs,
            localincs=barlocalincs,
            resources=barresources,
            misc=barmisc,
            buildtarget=[dll[0]] * 2,
            variant=('Debug|Win32', 'Release|Win32'),
            cmdargs=f'vc={msvcver}',
            DebugSettings=(dbgSettings, {}),
        )

MSVSSolution(), env.MSVSSolution()
    Build a Microsoft Visual Studio Solution file.

    Builds a Visual Studio solution file based on the version of Visual Studio that is configured: either the latest installed version, or the version specified by $MSVC_VERSION in the construction environment. For Visual Studio 6, a .dsw file is generated. For Visual Studio .NET 2002 and later, it will generate a .sln file. Note there are multiple versioning schemes involved in the Microsoft compilation environment - see the description of $MSVC_VERSION for equivalences.

    The solution file is a container for one or more projects, and follows the format described at https://learn.microsoft.com/en-us/visualstudio/extensibility/internals/solution-dot-sln-file[5].

    The following values must be specified:

    target
        The name of the target .dsw or .sln file. The correct suffix for the version of Visual Studio must be used, but the value $MSVSSOLUTIONSUFFIX will be defined to the correct value (see example below).

    variant
        The name of this particular variant, or a list of variant names (the latter is only supported for MSVS 7 solutions). These are typically things like "Debug" or "Release", but really can be anything you want. For MSVS 7 they may also specify target platform, like this "Debug|Xbox". Default platform is Win32.

    projects
        A list of project file names, or Project nodes returned by calls to the MSVSProject Builder, to be placed into the solution file. Note that these filenames need to be specified as strings, NOT as SCons File Nodes. This is because the solution file will be interpreted by MSBuild and by Visual Studio, which know nothing about SCons Node types.

    Example Usage:

        env.MSVSSolution(
            target="Bar" + env["MSVSSOLUTIONSUFFIX"],
            projects=["bar" + env["MSVSPROJECTSUFFIX"]],
            variant="Release",
        )

Ninja(), env.Ninja()
    A special builder which adds a target to create a Ninja build file. The builder does not require any source files to be specified.

        Note
        This is an experimental feature. To enable it you must use one of the following methods

            # On the command line
            --experimental=ninja
            # Or in your SConstruct
            SetOption('experimental', 'ninja')

        This functionality is subject to change and/or removal without deprecation cycle.

        To use this tool you need to install the Python ninja package, as the tool by default depends on being able to do an import of the package This can be done via:

            python -m pip install ninja

    If called with no arguments, the builder will default to a target name of ninja.build.

    If called with a single positional argument, scons will "deduce" the target name from that source argument, giving it the same name, and then ignore the source. This is the usual way to call the builder if a non-default target name is wanted.

    If called with either the target= or source= keyword arguments, the value of the argument is taken as the target name. If called with both, the target= value is used and source= is ignored. If called with multiple sources, the source list will be ignored, since there is no way to deduce what the intent was; in this case the default target name will be used.

    Available since scons 4.2.

Object(), env.Object()
    A synonym for the StaticObject builder method.

Package(), env.Package()
    Builds software distribution packages. A package is a container format which includes files to install along with metadata. Packaging is optional, and must be enabled by specifying the packaging tool. For example:

        env = Environment(tools=['default', 'packaging'])

    SCons can build packages in a number of well known packaging formats. The target package type may be selected with the the $PACKAGETYPE construction variable or the --package-type command line option. The package type may be a list, in which case SCons will attempt to build packages for each type in the list. Example:

        env.Package(PACKAGETYPE=['src_zip', 'src_targz'], ...other args...)

    The currently supported packagers are:
    msi | Microsoft Installer package
    rpm | RPM Package Manger package
    ipkg | Itsy Package Management package
    tarbz2 | bzip2-compressed tar file
    targz | gzip-compressed tar file
    tarxz | xz-compressed tar file
    zip | zip file
    src_tarbz2 | bzip2-compressed tar file suitable as source to another packager
    src_targz | gzip-compressed tar file suitable as source to another packager
    src_tarxz | xz-compressed tar file suitable as source to another packager
    src_zip | zip file suitable as source to another packager

    The file list to include in the package may be specified with the source keyword argument. If omitted, the FindInstalledFiles function is called behind the scenes to select all files that have an Install, InstallAs or InstallVersionedLib Builder attached. If the target keyword argument is omitted, the target name(s) will be deduced from the package type(s).

    The metadata comes partly from attributes of the files to be packaged, and partly from packaging tags. Tags can be passed as keyword arguments to the Package builder call, and may also be attached to files (or more accurately, Nodes representing files) with the Tag function. Some package-level tags are mandatory, and will lead to errors if omitted. The mandatory tags vary depending on the package type.

    While packaging, the builder uses a temporary location named by the value of the $PACKAGEROOT variable - the package sources are copied there before packaging.

    Packaging example:

        env = Environment(tools=["default", "packaging"])
        env.Install("/bin/", "my_program")
        env.Package(
            NAME="foo",
            VERSION="1.2.3",
            PACKAGEVERSION=0,
            PACKAGETYPE="rpm",
            LICENSE="gpl",
            SUMMARY="balalalalal",
            DESCRIPTION="this should be really really long",
            X_RPM_GROUP="Application/fu",
            SOURCE_URL="https://foo.org/foo-1.2.3.tar.gz",
        )

    In this example, the target /bin/my_program created by the Install call would not be built by default since it is not under the project top directory. However, since no source is specified to the Package builder, it is selected for packaging by the default sources rule. Since packaging is done using $PACKAGEROOT, no write is actually done to the system's /bin directory, and the target will be selected since after rebasing to underneath $PACKAGEROOT it is now under the top directory of the project.

PCH(), env.PCH()
    Builds a Microsoft Visual C++ precompiled header. Calling this builder returns a list of two target nodes: the PCH as the first element, and the object file as the second element. Normally the object file is ignored. The PCH builder is generally used in conjunction with the $PCH construction variable to force object files to use the precompiled header:

        env['PCH'] = env.PCH('StdAfx.cpp')[0]

        Note
        This builder is specific to the PCH implementation in Microsoft Visual C++. Other compiler chains also implement precompiled header support, but PCH does not work with them at this time. As a result, the builder is only generated into the construction environment when Microsoft Visual C++ is being used as the compiler.

        The builder only works correctly in a C++ project. The Microsoft implementation distinguishes between precompiled headers from C and C++. Use of the builder will cause the PCH generation to happen with a flag that tells cl.exe all of the files are C++ files; if that PCH file is then supplied when compiling a C source file, cl.exe will fail the build with a compatibility violation.

        If possible, arrange the project so that a C++ source file passed to the PCH builder is not also included in the list of sources to be otherwise compiled in the project. SCons will correctly track that file in the dependency tree as a result of the PCH call, and (for MSVC 11.0 and greater) automatically add the corresponding object file to the link line. If the source list is automatically generated, for example using the Glob function, it may be necessary to remove that file from the list.

PDF(), env.PDF()
    Builds a .pdf file from a .dvi input file (or, by extension, a .tex, .ltx, or .latex input file). The suffix specified by the $PDFSUFFIX construction variable (.pdf by default) is added automatically to the target if it is not already present. Example:

        # builds from aaa.tex
        env.PDF(target = 'aaa.pdf', source = 'aaa.tex')
        # builds bbb.pdf from bbb.dvi
        env.PDF(target = 'bbb', source = 'bbb.dvi')

POInit(), env.POInit()
    This builder belongs to msginit tool. The builder initializes missing PO file(s) if $POAUTOINIT is set. If $POAUTOINIT is not set (default), POInit prints instruction for user (that is supposed to be a translator), telling how the PO file should be initialized. In normal projects you should not use POInit and use POUpdate instead. POUpdate chooses intelligently between msgmerge(1) and msginit(1). POInit always uses msginit(1) and should be regarded as builder for special purposes or for temporary use (e.g. for quick, one time initialization of a bunch of PO files) or for tests.

    Target nodes defined through POInit are not built by default (they're Ignored from '.' node) but are added to special Alias ('po-create' by default). The alias name may be changed through the $POCREATE_ALIAS construction variable. All PO files defined through POInit may be easily initialized by scons po-create.

    Example 1. Initialize en.po and pl.po from messages.pot:

          # ...
          env.POInit(['en', 'pl']) # messages.pot --> [en.po, pl.po]

    Example 2. Initialize en.po and pl.po from foo.pot:

          # ...
          env.POInit(['en', 'pl'], ['foo']) # foo.pot --> [en.po, pl.po]

    Example 3. Initialize en.po and pl.po from foo.pot but using $POTDOMAIN construction variable:

          # ...
          env.POInit(['en', 'pl'], POTDOMAIN='foo') # foo.pot --> [en.po, pl.po]

    Example 4. Initialize PO files for languages defined in LINGUAS file. The files will be initialized from template messages.pot:

          # ...
          env.POInit(LINGUAS_FILE = 1) # needs 'LINGUAS' file

    Example 5. Initialize en.po and pl.pl PO files plus files for languages defined in LINGUAS file. The files will be initialized from template messages.pot:

          # ...
          env.POInit(['en', 'pl'], LINGUAS_FILE = 1)

    Example 6. You may preconfigure your environment first, and then initialize PO files:

          # ...
          env['POAUTOINIT'] = 1
          env['LINGUAS_FILE'] = 1
          env['POTDOMAIN'] = 'foo'
          env.POInit()

    which has same efect as:

          # ...
          env.POInit(POAUTOINIT = 1, LINGUAS_FILE = 1, POTDOMAIN = 'foo')

PostScript(), env.PostScript()
    Builds a .ps file from a .dvi input file (or, by extension, a .tex, .ltx, or .latex input file). The suffix specified by the $PSSUFFIX construction variable (.ps by default) is added automatically to the target if it is not already present. Example:

        # builds from aaa.tex
        env.PostScript(target = 'aaa.ps', source = 'aaa.tex')
        # builds bbb.ps from bbb.dvi
        env.PostScript(target = 'bbb', source = 'bbb.dvi')

POTUpdate(), env.POTUpdate()
    The builder belongs to xgettext tool. The builder updates target POT file if exists or creates one if it doesn't. The node is not built by default (i.e. it is Ignored from '.'), but only on demand (i.e. when given POT file is required or when special alias is invoked). This builder adds its targe node (messages.pot, say) to a special alias (pot-update by default, see $POTUPDATE_ALIAS) so you can update/create them easily with scons pot-update. The file is not written until there is no real change in internationalized messages (or in comments that enter POT file).

        Note
        You may see xgettext(1) being invoked by the xgettext tool even if there is no real change in internationalized messages (so the POT file is not being updated). This happens every time a source file has changed. In such case we invoke xgettext(1) and compare its output with the content of POT file to decide whether the file should be updated or not.

    Example 1. Let's create po/ directory and place following SConstruct script there:

          # SConstruct in 'po/' subdir
          env = Environment( tools = ['default', 'xgettext'] )
          env.POTUpdate(['foo'], ['../a.cpp', '../b.cpp'])
          env.POTUpdate(['bar'], ['../c.cpp', '../d.cpp'])

    Then invoke scons few times:

          user@host:$ scons             # Does not create foo.pot nor bar.pot
          user@host:$ scons foo.pot     # Updates or creates foo.pot
          user@host:$ scons pot-update  # Updates or creates foo.pot and bar.pot
          user@host:$ scons -c          # Does not clean foo.pot nor bar.pot.

    the results shall be as the comments above say.

    Example 2. The POTUpdate builder may be used with no target specified, in which case default target messages.pot will be used. The default target may also be overridden by setting $POTDOMAIN construction variable or providing it as an override to POTUpdate builder:

          # SConstruct script
          env = Environment( tools = ['default', 'xgettext'] )
          env['POTDOMAIN'] = "foo"
          env.POTUpdate(source = ["a.cpp", "b.cpp"]) # Creates foo.pot ...
          env.POTUpdate(POTDOMAIN = "bar", source = ["c.cpp", "d.cpp"]) # and bar.pot

    Example 3. The sources may be specified within separate file, for example POTFILES.in:

          # POTFILES.in in 'po/' subdirectory
          ../a.cpp
          ../b.cpp
          # end of file

    The name of the file (POTFILES.in) containing the list of sources is provided via $XGETTEXTFROM:

          # SConstruct file in 'po/' subdirectory
          env = Environment( tools = ['default', 'xgettext'] )
          env.POTUpdate(XGETTEXTFROM = 'POTFILES.in')

    Example 4. You may use $XGETTEXTPATH to define source search path. Assume, for example, that you have files a.cpp, b.cpp, po/SConstruct, po/POTFILES.in. Then your POT-related files could look as below:

          # POTFILES.in in 'po/' subdirectory
          a.cpp
          b.cpp
          # end of file

          # SConstruct file in 'po/' subdirectory
          env = Environment( tools = ['default', 'xgettext'] )
          env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH='../')

    Example 5. Multiple search directories may be defined within a list, i.e. XGETTEXTPATH = ['dir1', 'dir2', ...]. The order in the list determines the search order of source files. The path to the first file found is used.

    Let's create 0/1/po/SConstruct script:

          # SConstruct file in '0/1/po/' subdirectory
          env = Environment( tools = ['default', 'xgettext'] )
          env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH=['../', '../../'])

    and 0/1/po/POTFILES.in:

          # POTFILES.in in '0/1/po/' subdirectory
          a.cpp
          # end of file

    Write two *.cpp files, the first one is 0/a.cpp:

          /* 0/a.cpp */
          gettext("Hello from ../../a.cpp")

    and the second is 0/1/a.cpp:

          /* 0/1/a.cpp */
          gettext("Hello from ../a.cpp")

    then run scons. You'll obtain 0/1/po/messages.pot with the message "Hello from ../a.cpp". When you reverse order in $XGETTEXTFOM, i.e. when you write SConscript as

          # SConstruct file in '0/1/po/' subdirectory
          env = Environment( tools = ['default', 'xgettext'] )
          env.POTUpdate(XGETTEXTFROM = 'POTFILES.in', XGETTEXTPATH=['../../', '../'])

    then the messages.pot will contain msgid "Hello from ../../a.cpp" line and not msgid "Hello from ../a.cpp".

POUpdate(), env.POUpdate()
    The builder belongs to msgmerge tool. The builder updates PO files with msgmerge(1), or initializes missing PO files as described in documentation of msginit tool and POInit builder (see also $POAUTOINIT). Note, that POUpdate does not add its targets to po-create alias as POInit does.

    Target nodes defined through POUpdate are not built by default (they're Ignored from '.' node). Instead, they are added automatically to special Alias ('po-update' by default). The alias name may be changed through the $POUPDATE_ALIAS construction variable. You can easily update PO files in your project by scons po-update.

    Example 1. Update en.po and pl.po from messages.pot template (see also $POTDOMAIN), assuming that the later one exists or there is rule to build it (see POTUpdate):

          # ...
          env.POUpdate(['en','pl']) # messages.pot --> [en.po, pl.po]

    Example 2. Update en.po and pl.po from foo.pot template:

          # ...
          env.POUpdate(['en', 'pl'], ['foo']) # foo.pot -->  [en.po, pl.pl]

    Example 3. Update en.po and pl.po from foo.pot (another version):

          # ...
          env.POUpdate(['en', 'pl'], POTDOMAIN='foo') # foo.pot -- > [en.po, pl.pl]

    Example 4. Update files for languages defined in LINGUAS file. The files are updated from messages.pot template:

          # ...
          env.POUpdate(LINGUAS_FILE = 1) # needs 'LINGUAS' file

    Example 5. Same as above, but update from foo.pot template:

          # ...
          env.POUpdate(LINGUAS_FILE = 1, source = ['foo'])

    Example 6. Update en.po and pl.po plus files for languages defined in LINGUAS file. The files are updated from messages.pot template:

          # produce 'en.po', 'pl.po' + files defined in 'LINGUAS':
          env.POUpdate(['en', 'pl' ], LINGUAS_FILE = 1)

    Example 7. Use $POAUTOINIT to automatically initialize PO file if it doesn't exist:

          # ...
          env.POUpdate(LINGUAS_FILE = 1, POAUTOINIT = 1)

    Example 8. Update PO files for languages defined in LINGUAS file. The files are updated from foo.pot template. All necessary settings are pre-configured via environment.

          # ...
          env['POAUTOINIT'] = 1
          env['LINGUAS_FILE'] = 1
          env['POTDOMAIN'] = 'foo'
          env.POUpdate()

Program(), env.Program()
    Builds an executable given one or more object files or C, C++, D, or Fortran source files. If any C, C++, D or Fortran source files are specified, then they will be automatically compiled to object files using the Object builder method; see that builder method's description for a list of legal source file suffixes and how they are interpreted. The target executable file prefix, specified by the $PROGPREFIX construction variable (nothing by default), and suffix, specified by the $PROGSUFFIX construction variable (by default, .exe on Windows systems, nothing on POSIX systems), are automatically added to the target if not already present. Example:

        env.Program(target='foo', source=['foo.o', 'bar.c', 'baz.f'])

ProgramAllAtOnce(), env.ProgramAllAtOnce()
    Builds an executable from D sources without first creating individual objects for each file.

    D sources can be compiled file-by-file as C and C++ source are, and D is integrated into the scons Object and Program builders for this model of build. D codes can though do whole source meta-programming (some of the testing frameworks do this). For this it is imperative that all sources are compiled and linked in a single call to the D compiler. This builder serves that purpose.

            env.ProgramAllAtOnce('executable', ['mod_a.d, mod_b.d', 'mod_c.d'])

    This command will compile the modules mod_a, mod_b, and mod_c in a single compilation process without first creating object files for the modules. Some of the D compilers will create executable.o others will not.

RES(), env.RES()
    Builds a Microsoft Visual C++ resource file. This builder method is only provided when Microsoft Visual C++ or MinGW is being used as the compiler. The .res (or .o for MinGW) suffix is added to the target name if no other suffix is given. The source file is scanned for implicit dependencies as though it were a C file. Example:

        env.RES('resource.rc')

RMIC(), env.RMIC()
    Builds stub and skeleton class files for remote objects from Java .class files. The target is a directory relative to which the stub and skeleton class files will be written. The source can be the names of .class files, or the objects return from the Java builder method.

    If the construction variable $JAVACLASSDIR is set, either in the environment or in the call to the RMIC builder method itself, then the value of the variable will be stripped from the beginning of any .class file names.

        classes = env.Java(target='classdir', source='src')
        env.RMIC(target='outdir1', source=classes)
        env.RMIC(
            target='outdir2',
            source=['package/foo.class', 'package/bar.class'],
        )
        env.RMIC(
            target='outdir3',
            source=['classes/foo.class', 'classes/bar.class'],
            JAVACLASSDIR='classes',
        )

RPCGenClient(), env.RPCGenClient()
    Generates an RPC client stub (_clnt.c) file from a specified RPC (.x) source file. Because rpcgen only builds output files in the local directory, the command will be executed in the source file's directory by default.

        # Builds src/rpcif_clnt.c
        env.RPCGenClient('src/rpcif.x')

RPCGenHeader(), env.RPCGenHeader()
    Generates an RPC header (.h) file from a specified RPC (.x) source file. Because rpcgen only builds output files in the local directory, the command will be executed in the source file's directory by default.

        # Builds src/rpcif.h
        env.RPCGenHeader('src/rpcif.x')

RPCGenService(), env.RPCGenService()
    Generates an RPC server-skeleton (_svc.c) file from a specified RPC (.x) source file. Because rpcgen only builds output files in the local directory, the command will be executed in the source file's directory by default.

        # Builds src/rpcif_svc.c
        env.RPCGenClient('src/rpcif.x')

RPCGenXDR(), env.RPCGenXDR()
    Generates an RPC XDR routine (_xdr.c) file from a specified RPC (.x) source file. Because rpcgen only builds output files in the local directory, the command will be executed in the source file's directory by default.

        # Builds src/rpcif_xdr.c
        env.RPCGenClient('src/rpcif.x')

SharedLibrary(), env.SharedLibrary()
    Builds a shared library given one or more object files and/or C, C++, D or Fortran source files. Any source files listed in the source parameter will be automatically compiled to object files suitable for use in a shared library. Any object files listed in the source parameter must have been built for a shared library (that is, using the SharedObject builder method). scons will raise an error if there is any mismatch.

    The target library file prefix, specified by the $SHLIBPREFIX construction variable (by default, lib on POSIX systems, nothing on Windows systems), and suffix, specified by the $SHLIBSUFFIX construction variable (by default, .dll on Windows systems, .so on POSIX systems), are automatically added (if not already present) to the target name to make up the library filename. On a POSIX system, if the $SHLIBVERSION construction variable is set, it is appended (following a period) to the resulting library name.

    Example:

        env.SharedLibrary(target='bar', source=['bar.c', 'foo.o'])

    On Windows systems, the SharedLibrary builder method will always build an import library (.lib) in addition to the shared library (.dll), adding a .lib library with the same basename if there is not already a .lib file explicitly listed in the targets.

    On Cygwin systems, the SharedLibrary builder method will always build an import library (.dll.a) in addition to the shared library (.dll), adding a .dll.a library with the same basename if there is not already a .dll.a file explicitly listed in the targets.

    On some platforms, there is a distinction between a shared library (loaded automatically by the system to resolve external references) and a loadable module (explicitly loaded by user action). For maximum portability, use the LoadableModule builder for the latter.

    If $SHLIBVERSION is defined, a versioned shared library is created. This modifies $SHLINKFLAGS as required, adds the version number to the library name, and creates any symbolic links that are needed.

        env.SharedLibrary(target='bar', source=['bar.c', 'foo.o'], SHLIBVERSION='1.5.2')

    On a POSIX system, supplying a simple version string (no dots) creates exactly one symbolic link: SHLIBVERSION="1" would create (for example) library libbar.so.1 and symbolic link libbar.so. Supplying a dotted version string will create two symbolic links (irrespective of the number of segments in the version): SHLIBVERSION="1.5.2" for the same library would create library libbar.so.1.5.2 and symbolic links libbar.so and libbar.so.1. A Darwin (OSX) system creates one symlink in either case, for the second example the library would be libbar.1.5.2.dylib and the link would be libbar.dylib.

    On Windows systems, specifying the register=1 keyword argument will cause the .dll to be registered after it is built. The command that is run is determined by the $REGSVR construction variable (regsvr32 by default), and the flags passed are determined by $REGSVRFLAGS. By default, $REGSVRFLAGS includes the /s option, to prevent dialogs from popping up and requiring user attention when it is run. If you change $REGSVRFLAGS, be sure to include the /s option. For example,

        env.SharedLibrary(target='bar', source=['bar.cxx', 'foo.obj'], register=1)

    will register bar.dll as a COM object when it is done linking it.

SharedObject(), env.SharedObject()
    Builds an object file intended for inclusion in a shared library. Source files must have one of the same set of extensions specified above for the StaticObject builder method. On some platforms building a shared object requires additional compiler option (e.g. -fPIC for gcc) in addition to those needed to build a normal (static) object, but on some platforms there is no difference between a shared object and a normal (static) one. When there is a difference, SCons will only allow shared objects to be linked into a shared library, and will use a different suffix for shared objects. On platforms where there is no difference, SCons will allow both normal (static) and shared objects to be linked into a shared library, and will use the same suffix for shared and normal (static) objects. The target object file prefix, specified by the $SHOBJPREFIX construction variable (by default, the same as $OBJPREFIX), and suffix, specified by the $SHOBJSUFFIX construction variable, are automatically added to the target if not already present. Examples:

        env.SharedObject(target='ddd', source='ddd.c')
        env.SharedObject(target='eee.o', source='eee.cpp')
        env.SharedObject(target='fff.obj', source='fff.for')

    Note that the source files will be scanned according to the suffix mappings in the SourceFileScanner object. See the manpage section "Scanner Objects" for more information.

StaticLibrary(), env.StaticLibrary()
    Builds a static library given one or more object files or C, C++, D or Fortran source files. If any source files are given, then they will be automatically compiled to object files. The static library file prefix, specified by the $LIBPREFIX construction variable (by default, lib on POSIX systems, nothing on Windows systems), and suffix, specified by the $LIBSUFFIX construction variable (by default, .lib on Windows systems, .a on POSIX systems), are automatically added to the target if not already present. Example:

        env.StaticLibrary(target='bar', source=['bar.c', 'foo.o'])

    Any object files listed in the source must have been built for a static library (that is, using the StaticObject builder method). scons will raise an error if there is any mismatch.

StaticObject(), env.StaticObject()
    Builds a static object file from one or more C, C++, D, or Fortran source files. Source files must have one of the following extensions:

          .asm    assembly language file
          .ASM    assembly language file
          .c      C file
          .C      Windows:  C file
                  POSIX:  C++ file
          .cc     C++ file
          .cpp    C++ file
          .cxx    C++ file
          .cxx    C++ file
          .c++    C++ file
          .C++    C++ file
          .d      D file
          .f      Fortran file
          .F      Windows:  Fortran file
                  POSIX:  Fortran file + C pre-processor
          .for    Fortran file
          .FOR    Fortran file
          .fpp    Fortran file + C pre-processor
          .FPP    Fortran file + C pre-processor
          .m      Object C file
          .mm     Object C++ file
          .s      assembly language file
          .S      Windows:  assembly language file
                  ARM: CodeSourcery Sourcery Lite
          .sx     assembly language file + C pre-processor
                  POSIX:  assembly language file + C pre-processor
          .spp    assembly language file + C pre-processor
          .SPP    assembly language file + C pre-processor

    The target object file prefix, specified by the $OBJPREFIX construction variable (nothing by default), and suffix, specified by the $OBJSUFFIX construction variable (.obj on Windows systems, .o on POSIX systems), are automatically added to the target if not already present. Examples:

        env.StaticObject(target='aaa', source='aaa.c')
        env.StaticObject(target='bbb.o', source='bbb.c++')
        env.StaticObject(target='ccc.obj', source='ccc.f')

    Note that the source files will be scanned according to the suffix mappings in the SourceFileScanner object. See the manpage section "Scanner Objects" for more information.

Substfile(), env.Substfile()
    The Substfile builder creates a single text file from a template consisting of a file or set of files (or nodes), replacing text using the $SUBST_DICT construction variable (if set). If a set, they are concatenated into the target file using the value of the $LINESEPARATOR construction variable as a separator between contents; the separator is not emitted after the contents of the last file. Nested lists of source files are flattened. See also Textfile.

    By default the target file encoding is "utf-8" and can be changed by $FILE_ENCODING Examples:

    If a single source file name is specified and has a .in suffix, the suffix is stripped and the remainder of the name is used as the default target name.

    The prefix and suffix specified by the $SUBSTFILEPREFIX and $SUBSTFILESUFFIX construction variables (an empty string by default in both cases) are automatically added to the target if they are not already present.

    If a construction variable named $SUBST_DICT is present, it may be either a Python dictionary or a sequence of (key, value) tuples. If it is a dictionary it is converted into a list of tuples with unspecified order, so if one key is a prefix of another key or if one substitution could be further expanded by another subsitition, it is unpredictable whether the expansion will occur.

    Any occurrences of a key in the source are replaced by the corresponding value, which may be a Python callable function or a string. If the value is a callable, it is called with no arguments to get a string. Strings are subst-expanded and the result replaces the key.

        env = Environment(tools=['default'])
        env['prefix'] = '/usr/bin'
        script_dict = {'@prefix@': '/bin', '@exec_prefix@': '$prefix'}
        env.Substfile('script.in', SUBST_DICT=script_dict)
        conf_dict = {'%VERSION%': '1.2.3', '%BASE%': 'MyProg'}
        env.Substfile('config.h.in', conf_dict, SUBST_DICT=conf_dict)
        # UNPREDICTABLE - one key is a prefix of another
        bad_foo = {'$foo': '$foo', '$foobar': '$foobar'}
        env.Substfile('foo.in', SUBST_DICT=bad_foo)
        # PREDICTABLE - keys are applied longest first
        good_foo = [('$foobar', '$foobar'), ('$foo', '$foo')]
        env.Substfile('foo.in', SUBST_DICT=good_foo)
        # UNPREDICTABLE - one substitution could be futher expanded
        bad_bar = {'@bar@': '@soap@', '@soap@': 'lye'}
        env.Substfile('bar.in', SUBST_DICT=bad_bar)
        # PREDICTABLE - substitutions are expanded in order
        good_bar = (('@bar@', '@soap@'), ('@soap@', 'lye'))
        env.Substfile('bar.in', SUBST_DICT=good_bar)
        # the SUBST_DICT may be in common (and not an override)
        substutions = {}
        subst = Environment(tools=['textfile'], SUBST_DICT=substitutions)
        substitutions['@foo@'] = 'foo'
        subst['SUBST_DICT']['@bar@'] = 'bar'
        subst.Substfile(
            'pgm1.c',
            [Value('#include "@foo@.h"'), Value('#include "@bar@.h"'), "common.in", "pgm1.in"],
        )
        subst.Substfile(
            'pgm2.c',
            [Value('#include "@foo@.h"'), Value('#include "@bar@.h"'), "common.in", "pgm2.in"],
        )

Tar(), env.Tar()
    Builds a tar archive of the specified files and/or directories. Unlike most builder methods, the Tar builder method may be called multiple times for a given target; each additional call adds to the list of entries that will be built into the archive. Any source directories will be scanned for changes to any on-disk files, regardless of whether or not scons knows about them from other Builder or function calls.

        env.Tar('src.tar', 'src')
        # Create the stuff.tar file.
        env.Tar('stuff', ['subdir1', 'subdir2'])
        # Also add "another" to the stuff.tar file.
        env.Tar('stuff', 'another')
        # Set TARFLAGS to create a gzip-filtered archive.
        env = Environment(TARFLAGS = '-c -z')
        env.Tar('foo.tar.gz', 'foo')
        # Also set the suffix to .tgz.
        env = Environment(TARFLAGS = '-c -z',
                          TARSUFFIX = '.tgz')
        env.Tar('foo')

Textfile(), env.Textfile()
    The Textfile builder generates a single text file from a template consisting of a list of strings, replacing text using the $SUBST_DICT construction variable (if set) - see Substfile for a description of replacement. The strings will be separated in the target file using the value of the $LINESEPARATOR construction variable; the line separator is not emitted after the last string. Nested lists of source strings are flattened. Source strings need not literally be Python strings: they can be Nodes or Python objects that convert cleanly to Value nodes.

    The prefix and suffix specified by the $TEXTFILEPREFIX and $TEXTFILESUFFIX construction variables (by default an empty string and .txt, respectively) are automatically added to the target if they are not already present.

    By default the target file encoding is "utf-8" and can be changed by $FILE_ENCODING Examples:

        # builds/writes foo.txt
        env.Textfile(target='foo.txt', source=['Goethe', 42, 'Schiller'])
        # builds/writes bar.txt
        env.Textfile(target='bar', source=['lalala', 'tanteratei'], LINESEPARATOR='|*')
        # nested lists are flattened automatically
        env.Textfile(target='blob', source=['lalala', ['Goethe', 42, 'Schiller'], 'tanteratei'])
        # files may be used as input by wraping them in File()
        env.Textfile(
            target='concat',  # concatenate files with a marker between
            source=[File('concat1'), File('concat2')],
            LINESEPARATOR='====================\n',
        )

    Results:

    foo.txt

          Goethe
          42
          Schiller

    bar.txt

          lalala|*tanteratei

    blob.txt

          lalala
          Goethe
          42
          Schiller
          tanteratei

Translate(), env.Translate()
    This pseudo-builder belongs to gettext toolset. The builder extracts internationalized messages from source files, updates POT template (if necessary) and then updates PO translations (if necessary). If $POAUTOINIT is set, missing PO files will be automatically created (i.e. without translator person intervention). The variables $LINGUAS_FILE and $POTDOMAIN are taken into acount too. All other construction variables used by POTUpdate, and POUpdate work here too.

    Example 1. The simplest way is to specify input files and output languages inline in a SCons script when invoking Translate

        # SConscript in 'po/' directory
        env = Environment( tools = ["default", "gettext"] )
        env['POAUTOINIT'] = 1
        env.Translate(['en','pl'], ['../a.cpp','../b.cpp'])

    Example 2. If you wish, you may also stick to conventional style known from autotools, i.e. using POTFILES.in and LINGUAS files

        # LINGUAS
        en pl
        #end

        # POTFILES.in
        a.cpp
        b.cpp
        # end

        # SConscript
        env = Environment( tools = ["default", "gettext"] )
        env['POAUTOINIT'] = 1
        env['XGETTEXTPATH'] = ['../']
        env.Translate(LINGUAS_FILE = 1, XGETTEXTFROM = 'POTFILES.in')

    The last approach is perhaps the recommended one. It allows easily split internationalization/localization onto separate SCons scripts, where a script in source tree is responsible for translations (from sources to PO files) and script(s) under variant directories are responsible for compilation of PO to MO files to and for installation of MO files. The "gluing factor" synchronizing these two scripts is then the content of LINGUAS file. Note, that the updated POT and PO files are usually going to be committed back to the repository, so they must be updated within the source directory (and not in variant directories). Additionaly, the file listing of po/ directory contains LINGUAS file, so the source tree looks familiar to translators, and they may work with the project in their usual way.

    Example 3. Let's prepare a development tree as below

         project/
          + SConstruct
          + build/
          + src/
              + po/
                  + SConscript
                  + SConscript.i18n
                  + POTFILES.in
                  + LINGUAS

    with build being variant directory. Write the top-level SConstruct script as follows

          # SConstruct
          env = Environment( tools = ["default", "gettext"] )
          VariantDir('build', 'src', duplicate = 0)
          env['POAUTOINIT'] = 1
          SConscript('src/po/SConscript.i18n', exports = 'env')
          SConscript('build/po/SConscript', exports = 'env')

    the src/po/SConscript.i18n as

          # src/po/SConscript.i18n
          Import('env')
          env.Translate(LINGUAS_FILE=1, XGETTEXTFROM='POTFILES.in', XGETTEXTPATH=['../'])

    and the src/po/SConscript

          # src/po/SConscript
          Import('env')
          env.MOFiles(LINGUAS_FILE = 1)

    Such setup produces POT and PO files under source tree in src/po/ and binary MO files under variant tree in build/po/. This way the POT and PO files are separated from other output files, which must not be committed back to source repositories (e.g. MO files).

        Note
        In above example, the PO files are not updated, nor created automatically when you issue scons '.' command. The files must be updated (created) by hand via scons po-update and then MO files can be compiled by running scons '.'.

TypeLibrary(), env.TypeLibrary()
    Builds a Windows type library (.tlb) file from an input IDL file (.idl). In addition, it will build the associated interface stub and proxy source files, naming them according to the base name of the .idl file. For example,

        env.TypeLibrary(source="foo.idl")

    Will create foo.tlb, foo.h, foo_i.c, foo_p.c and foo_data.c files.

Uic(), env.Uic()
    Builds a header file, an implementation file and a moc file from an ui file. and returns the corresponding nodes in the that order. This builder is only available after using the tool qt3. Note: you can specify .ui files directly as source files to the Program, Library and SharedLibrary builders without using this builder. Using this builder lets you override the standard naming conventions (be careful: prefixes are always prepended to names of built files; if you don't want prefixes, you may set them to ``). See the $QT3DIR variable for more information. Example:

        env.Uic('foo.ui')  # -> ['foo.h', 'uic_foo.cc', 'moc_foo.cc']
        env.Uic(
            target=Split('include/foo.h gen/uicfoo.cc gen/mocfoo.cc'),
            source='foo.ui'
        )  # -> ['include/foo.h', 'gen/uicfoo.cc', 'gen/mocfoo.cc']

Zip(), env.Zip()
    Builds a zip archive of the specified files and/or directories. Unlike most builder methods, the Zip builder method may be called multiple times for a given target; each additional call adds to the list of entries that will be built into the archive. Any source directories will be scanned for changes to any on-disk files, regardless of whether or not scons knows about them from other Builder or function calls.

        env.Zip('src.zip', 'src')
        # Create the stuff.zip file.
        env.Zip('stuff', ['subdir1', 'subdir2'])
        # Also add "another" to the stuff.tar file.
        env.Zip('stuff', 'another')

All targets of builder methods automatically depend on their sources. An explicit dependency can be specified using the env.Depends method of a construction environment (see below).

In addition, scons automatically scans source files for various programming languages, so the dependencies do not need to be specified explicitly. By default, SCons can C source files, C++ source files, Fortran source files with .F (POSIX systems only), .fpp, or .FPP file extensions, and assembly language files with .S (POSIX systems only), .spp, or .SPP files extensions for C preprocessor dependencies. SCons also has default support for scanning D source files, You can also write your own Scanners to add support for additional source file types. These can be added to the default Scanner object used by the Object, StaticObject and SharedObject Builders by adding them to the SourceFileScanner object. See the section called “Scanner Objects” for more information about defining your own Scanner objects and using the SourceFileScanner object.

  SCons Functions and Environment Methods

SCons provides a variety of construction environment methods and global functions to manipulate the build configuration. Often, a construction environment method and a global function with the same name exist for convenience. In this section, both forms are shown if the function can be called in either way. The documentation style for these is as follows:

    Function(arguments, [optional arguments, ...])  # Global function
    env.Function(arguments, [optional arguments, ...])  # Environment method

In these function signatures, arguments in brackets ([]) are optional, and ellipses (...) indicate possible repetition. Positional vs. keyword arguments are usually detailed in the following text, not in the signature itself. The Python positional-only (/) and keyword-only (*) markers are not used.

When the Python keyword=value style is shown, it can have two meanings. If the keyword argument is known to the function, the value is the default for that argument if it is omitted. If the keyword is unknown to the function, some methods treat it as a construction variable assignment; otherwise an exception is raised for an unknown argument.

A global function and a same-named construction environment method have the same base functionality, with two key differences:

    1. Construction environment methods that change the environment act on the environment instance from which they are called, while the corresponding global function acts on a special “hidden” construction environment called the Default Environment. In some cases, the global function may take an initial argument giving the object to operate on.

    2. String-valued arguments (including strings in list-valued arguments) are subject to construction variable expansion by the environment method form; variable expansion is not immediately performed in the global function. For example, Default('$MYTARGET') adds '$MYTARGET' to the list of default targets, while if the value in env of MYTARGET is 'mine', env.Default('$MYTARGET' adds 'mine' to the default targets. For more details on construction variable expansion, see the Construction variables section.

Global functions are automatically in scope inside SConscript files. If your project adds Python modules that you include via the Python import statement from an SConscript file, such code will need to add the functions to that module’s global scope explicitly. You can do that by adding the following import to the Python module: from SCons.Script import *.

SCons provides the following construction environment methods and global functions. The list can be augmented on a project basis using AddMethod

Action(action, [output, [var, ...]] [key=value, ...]), env.Action(action, [output, [var, ...]] [key=value, ...])
    A factory function to create an Action object for the specified action. See the manpage section "Action Objects" for a complete explanation of the arguments and behavior.

    Note that the env.Action form of the invocation will expand construction variables in any argument strings, including the action argument, at the time it is called using the construction variables in the env construction environment through which env.Action was called. The Action global function form delays all variable expansion until the Action object is actually used.

AddMethod(object, function, [name]), env.AddMethod(function, [name])
    Adds function to an object as a method. function will be called with an instance object as the first argument as for other methods. If name is given, it is used as the name of the new method, else the name of function is used.

    When the global function AddMethod is called, the object to add the method to must be passed as the first argument; typically this will be Environment, in order to create a method which applies to all construction environments subsequently constructed. When called using the env.AddMethod form, the method is added to the specified construction environment only. Added methods propagate through env.Clone calls.

    More examples:

        # Function to add must accept an instance argument.
        # The Python convention is to call this 'self'.
        def my_method(self, arg):
            print("my_method() got", arg)
        # Use the global function to add a method to the Environment class:
        AddMethod(Environment, my_method)
        env = Environment()
        env.my_method('arg')
        # Use the optional name argument to set the name of the method:
        env.AddMethod(my_method, 'other_method_name')
        env.other_method_name('another arg')

AddOption(opt_str, ..., attr=value, ...)
    Adds a local (project-specific) command-line option. One or more opt_str values are the strings representing how the option can be called, while the keyword arguments define attributes of the option. For the most part these are the same as for the OptionParser.add_option method in the standard Python library module optparse, but with a few additional capabilities noted below. See the optparse documentation[6] for a thorough discussion of its option-processing capabities. All options added through AddOption are placed in a special "Local Options" option group.

    In addition to the arguments and values supported by the optparse add_option method, AddOption allows setting the nargs keyword value to a string '?' (question mark) to indicate that the option argument for that option string may be omitted. If the option string is present on the command line but has no matching option argument, the value of the const keyword argument is produced as the value of the option. If the option string is omitted from the command line, the value of the default keyword argument is produced, as usual; if there is no default keyword argument in the AddOption call, None is produced.

    optparse recognizes abbreviations of long option names, as long as they can be unambiguously resolved. For example, if add_option is called to define a --devicename option, it will recognize --device, --dev and so forth as long as there is no other option which could also match to the same abbreviation. Options added via AddOption do not support the automatic recognition of abbreviations. Instead, to allow specific abbreviations, include them as synonyms in the AddOption call itself.

    Once a new command-line option has been added with AddOption, the option value may be accessed using GetOption or env.GetOption. If the settable=True argument was supplied in the AddOption call, the value may also be set later using SetOption or env.SetOption, if conditions in an SConscript file require overriding any default value. Note however that a value specified on the command line will always override a value set in an SConscript file.

    Changed in 4.8.0: added the settable keyword argument to enable an added option to be settable via SetOption.

    Help text for an option is a combination of the string supplied in the help keyword argument to AddOption and information collected from the other keyword arguments. Such help is displayed if the -h command line option is used (but not with -H). Help for all local options is displayed under the separate heading Local Options. The options are unsorted - they will appear in the help text in the order in which the AddOption calls occur.

    Example:

        AddOption(
            '--prefix',
            dest='prefix',
            nargs=1,
            type='string',
            action='store',
            metavar='DIR',
            help='installation prefix',
        )
        env = Environment(PREFIX=GetOption('prefix'))

    For that example, the following help text would be produced:

        Local Options:
          --prefix=DIR                installation prefix

    Help text for local options may be unavailable if the Help function has been called, see the Help documentation for details.

        Note
        As an artifact of the internal implementation, the behavior of options added by AddOption which take option arguments is undefined if whitespace (rather than an = sign) is used as the separator on the command line. Users should avoid such usage; it is recommended to add a note to this effect to project documentation if the situation is likely to arise. In addition, if the nargs keyword is used to specify more than one following option argument (that is, with a value of 2 or greater), such arguments would necessarily be whitespace separated, triggering the issue. Developers should not use AddOption this way. Future versions of SCons will likely forbid such usage.

AddPostAction(target, action), env.AddPostAction(target, action)
    Arranges for the specified action to be performed after the specified target has been built. action may be an Action object, or anything that can be converted into an Action object. See the manpage section "Action Objects" for a complete explanation.

    When multiple targets are supplied, the action may be called multiple times, once after each action that generates one or more targets in the list.

        foo = Program('foo.c')
        # remove execute permission from binary:
        AddPostAction(foo, Chmod('$TARGET', "a-x"))

AddPreAction(target, action), env.AddPreAction(target, action)
    Arranges for the specified action to be performed before the specified target is built. action may be an Action object, or anything that can be converted into an Action object. See the manpage section "Action Objects" for a complete explanation.

    When multiple targets are specified, the action(s) may be called multiple times, once before each action that generates one or more targets in the list.

    Note that if any of the targets are built in multiple steps, the action will be invoked just before the "final" action that specifically generates the specified target(s). For example, when building an executable program from a specified source .c file via an intermediate object file:

        foo = Program('foo.c')
        AddPreAction(foo, 'pre_action')

    The specified pre_action would be executed before scons calls the link command that actually generates the executable program binary foo, not before compiling the foo.c file into an object file.

Alias(alias, [source, [action]]), env.Alias(alias, [source, [action]])
    Creates an alias target that can be used as a reference to zero or more other targets, specified by the optional source parameter. Aliases provide a way to give a shorter or more descriptive name to specific targets, and to group multiple targets under a single name. The alias name, or an Alias Node object, may be used as a dependency of any other target, including another alias.

    alias and source may each be a string or Node object, or a list of strings or Node objects; if Nodes are used for alias they must be Alias nodes. If source is omitted, the alias is created but has no reference; if selected for building this will result in a “Nothing to be done.” message. An empty alias can be used to define the alias in a visible place in the project; it can later be appended to in a subsidiary SConscript file with the actual target(s) to refer to. The optional action parameter specifies an action or list of actions that will be executed whenever the any of the alias targets are out-of-date.

    Alias can be called for an existing alias, which appends the alias and/or action arguments to the existing lists for that alias.

    Returns a list of Alias Node objects representing the alias(es), which exist outside of any physical file system. The alias name space is separate from the name space for tangible targets; to avoid confusion do not reuse target names as alias names.

    Examples:

        Alias('install')
        Alias('install', '/usr/bin')
        Alias(['install', 'install-lib'], '/usr/local/lib')
        env.Alias('install', ['/usr/local/bin', '/usr/local/lib'])
        env.Alias('install', ['/usr/local/man'])
        env.Alias('update', ['file1', 'file2'], "update_database $SOURCES")

AllowSubstExceptions([exception, ...])
    Specifies the exceptions that will be allowed when expanding construction variables. By default, any construction variable expansions that generate a NameError or IndexError exception will expand to a '' (an empty string) and not cause scons to fail. All exceptions not in the specified list will generate an error message and terminate processing.

    If AllowSubstExceptions is called multiple times, each call completely overwrites the previous list of allowed exceptions.

    Example:

        # Requires that all construction variable names exist.
        # (You may wish to do this if you want to enforce strictly
        # that all construction variables must be defined before use.)
        AllowSubstExceptions()
        # Also allow a string containing a zero-division expansion
        # like '${1 / 0}' to evalute to ''.
        AllowSubstExceptions(IndexError, NameError, ZeroDivisionError)

AlwaysBuild(target, ...), env.AlwaysBuild(target, ...)
    Marks each given target so that it is always assumed to be out of date, and will always be rebuilt if needed. Note, however, that AlwaysBuild does not add its target(s) to the default target list, so the targets will only be built if they are specified on the command line, or are a dependent of a target specified on the command line--but they will always be built if so specified. Multiple targets can be passed in to a single call to AlwaysBuild.

env.Append(key=val, [...])
    Appends value(s) intelligently to construction variables in env. The construction variables and values to add to them are passed as key=val pairs (Python keyword arguments). env.Append is designed to allow adding values without having to think about the data type of an existing construction variable. Regular Python syntax can also be used to manipulate the construction variable, but for that you may need to know the types involved, for example pure Python lets you directly "add" two lists of strings, but adding a string to a list or a list to a string requires different syntax - things Append takes care of. Some pre-defined construction variables do have type expectations based on how SCons will use them: for example $CPPDEFINES is often a string or a list of strings, but can also be a list of tuples or a dictionary; while $LIBEMITTER is expected to be a callable or list of callables, and $BUILDERS is expected to be a dictionary. Consult the documentation for the various construction variables for more details.

    The following descriptions apply to both the Append and Prepend methods, as well as their Unique variants, with the differences being the insertion point of the added values and whether duplication is allowed.

    val can be almost any type. If env does not have a construction variable named key, then key is simply stored with a value of val. Otherwise, val is combinined with the existing value, possibly converting into an appropriate type which can hold the expanded contents. There are a few special cases to be aware of. Normally, when two strings are combined, the result is a new string containing their concatenation (and you are responsible for supplying any needed separation); however, the contents of $CPPDEFINES will will be postprocessed by adding a prefix and/or suffix to each entry when the command line is produced, so SCons keeps them separate - appending a string will result in a separate string entry, not a combined string. For $CPPDEFINES. as well as $LIBS, and the various *PATH variables, SCons will amend the variable by supplying the compiler-specific syntax (e.g. prepending a -D or /D prefix for $CPPDEFINES), so you should omit this syntax when adding values to these variables. Examples (gcc syntax shown in the expansion of CPPDEFINES):

        env = Environment(CXXFLAGS="-std=c11", CPPDEFINES="RELEASE")
        print(f"CXXFLAGS = {env['CXXFLAGS']}, CPPDEFINES = {env['CPPDEFINES']}")
        # notice including a leading space in CXXFLAGS addition
        env.Append(CXXFLAGS=" -O", CPPDEFINES="EXTRA")
        print(f"CXXFLAGS = {env['CXXFLAGS']}, CPPDEFINES = {env['CPPDEFINES']}")
        print("CPPDEFINES will expand to", env.subst('$_CPPDEFFLAGS'))

        $ scons -Q
        CXXFLAGS = -std=c11, CPPDEFINES = RELEASE
        CXXFLAGS = -std=c11 -O, CPPDEFINES = deque(['RELEASE', 'EXTRA'])
        CPPDEFINES will expand to -DRELEASE -DEXTRA
        scons: `.' is up to date.

    Because $CPPDEFINES is intended for command-line specification of C/C++ preprocessor macros, additional syntax is accepted when adding to it. The preprocessor accepts arguments to predefine a macro name by itself (-DFOO for most compilers, /DFOO for Microsoft C++), which gives it an implicit value of 1, or can be given with a replacement value (-DBAR=TEXT). SCons follows these rules when adding to $CPPDEFINES:

        • A string is split on spaces, giving an easy way to enter multiple macros in one addition. Use an = to specify a valued macro.

        • A tuple is treated as a valued macro. Use the value None if the macro should not have a value. It is an error to supply more than two elements in such a tuple.

        • A list is processed in order, adding each item without further interpretation. In this case, space-separated strings are not split.

        • A dictionary is processed in order, adding each key-value pair as a valued macro. Use the value None if the macro should not have a value.

    Examples:

        env = Environment(CPPDEFINES="FOO")
        print("CPPDEFINES =", env['CPPDEFINES'])
        env.Append(CPPDEFINES="BAR=1")
        print("CPPDEFINES =", env['CPPDEFINES'])
        env.Append(CPPDEFINES=[("OTHER", 2)])
        print("CPPDEFINES =", env['CPPDEFINES'])
        env.Append(CPPDEFINES={"EXTRA": "arg"})
        print("CPPDEFINES =", env['CPPDEFINES'])
        print("CPPDEFINES will expand to", env.subst('$_CPPDEFFLAGS'))

        $ scons -Q
        CPPDEFINES = FOO
        CPPDEFINES = deque(['FOO', 'BAR=1'])
        CPPDEFINES = deque(['FOO', 'BAR=1', ('OTHER', 2)])
        CPPDEFINES = deque(['FOO', 'BAR=1', ('OTHER', 2), ('EXTRA', 'arg')])
        CPPDEFINES will expand to -DFOO -DBAR=1 -DOTHER=2 -DEXTRA=arg
        scons: `.' is up to date.

    Examples of adding multiple macros:

        env = Environment()
        env.Append(CPPDEFINES=[("ONE", 1), "TWO", ("THREE", )])
        print("CPPDEFINES =", env['CPPDEFINES'])
        env.Append(CPPDEFINES={"FOUR": 4, "FIVE": None})
        print("CPPDEFINES =", env['CPPDEFINES'])
        print("CPPDEFINES will expand to", env.subst('$_CPPDEFFLAGS'))

        $ scons -Q
        CPPDEFINES = [('ONE', 1), 'TWO', ('THREE',)]
        CPPDEFINES = deque([('ONE', 1), 'TWO', ('THREE',), ('FOUR', 4), ('FIVE', None)])
        CPPDEFINES will expand to -DONE=1 -DTWO -DTHREE -DFOUR=4 -DFIVE
        scons: `.' is up to date.

    Changed in version 4.5: clarifined the use of tuples vs. other types, handling is now consistent across the four functions.

        env = Environment()
        env.Append(CPPDEFINES=("MACRO1", "MACRO2"))
        print("CPPDEFINES =", env['CPPDEFINES'])
        env.Append(CPPDEFINES=[("MACRO3", "MACRO4")])
        print("CPPDEFINES =", env['CPPDEFINES'])
        print("CPPDEFINES will expand to", env.subst('$_CPPDEFFLAGS'))

        $ scons -Q
        CPPDEFINES = ('MACRO1', 'MACRO2')
        CPPDEFINES = deque(['MACRO1', 'MACRO2', ('MACRO3', 'MACRO4')])
        CPPDEFINES will expand to -DMACRO1 -DMACRO2 -DMACRO3=MACRO4
        scons: `.' is up to date.

    See $CPPDEFINES for more details.

    Appending a string val to a dictonary-typed construction variable enters val as the key in the dictionary, and None as its value. Using a tuple type to supply a key-value pair only works for the special case of $CPPDEFINES described above.

    Although most combinations of types work without needing to know the details, some combinations do not make sense and Python raises an exception.

    When using env.Append to modify construction variables which are path specifications (conventionally, the names of such end in PATH), it is recommended to add the values as a list of strings, even if you are only adding a single string. The same goes for adding library names to $LIBS.

        env.Append(CPPPATH=["#/include"])

    See also env.AppendUnique, env.Prepend and env.PrependUnique.

env.AppendENVPath(name, newpath, [envname, sep, delete_existing=False])
    Append path elements specified by newpath to the given search path string or list name in mapping envname in the construction environment. Supplying envname is optional: the default is the execution environment $ENV. Optional sep is used as the search path separator, the default is the platform's separator (os.pathsep). A path element will only appear once. Any duplicates in newpath are dropped, keeping the last appearing (to preserve path order). If delete_existing is False (the default) any addition duplicating an existing path element is ignored; if delete_existing is True the existing value will be dropped and the path element will be added at the end. To help maintain uniqueness all paths are normalized (using os.path.normpath and os.path.normcase).

    Example:

        print('before:', env['ENV']['INCLUDE'])
        include_path = '/foo/bar:/foo'
        env.AppendENVPath('INCLUDE', include_path)
        print('after:', env['ENV']['INCLUDE'])

    Yields:

        before: /foo:/biz
        after: /biz:/foo/bar:/foo

    See also env.PrependENVPath.

env.AppendUnique(key=val, [...], [delete_existing=False])
    Append values to construction variables in the current construction environment, maintaining uniqueness. Works like env.Append, except that values that would become duplicates are not added. If delete_existing is set to a true value, then for any duplicate, the existing instance of val is first removed, then val is appended, having the effect of moving it to the end.

    Example:

        env.AppendUnique(CCFLAGS='-g', FOO=['foo.yyy'])

    See also env.Append, env.Prepend and env.PrependUnique.

Builder(action, [arguments]), env.Builder(action, [arguments])
    Creates a Builder object for the specified action. See the manpage section "Builder Objects" for a complete explanation of the arguments and behavior.

    Note that the env.Builder() form of the invocation will expand construction variables in any arguments strings, including the action argument, at the time it is called using the construction variables in the env construction environment through which env.Builder was called. The Builder form delays all variable expansion until after the Builder object is actually called.

CacheDir(cache_dir, custom_class=None), env.CacheDir(cache_dir, custom_class=None)
    Direct scons to maintain a derived-file cache in cache_dir. The derived files in the cache will be shared among all the builds specifying the same cache_dir. Specifying a cache_dir of None disables derived file caching.

    Calling the environment method env.CacheDir limits the effect to targets built through the specified construction environment. Calling the global function CacheDir sets a global default that will be used by all targets built through construction environments that do not set up environment-specific caching by calling env.CacheDir.

    Caching behavior can be configured by passing a specialized cache class as the optional custom_class parameter. This class must be a subclass of SCons.CacheDir.CacheDir. SCons will internally invoke the custom class for performing caching operations. If the parameter is omitted or set to None, SCons will use the default SCons.CacheDir.CacheDir class.

    When derived-file caching is being used and scons finds a derived file that needs to be rebuilt, it will first look in the cache to see if a file with matching build signature exists (indicating the input file(s) and build action(s) were identical to those for the current target), and if so, will retrieve the file from the cache. scons will report Retrieved `file' from cache instead of the normal build message. If the derived file is not present in the cache, scons will build it and then place a copy of the built file in the cache, identified by its build signature, for future use.

    The Retrieved `file' from cache messages are useful for human consumption, but less useful when comparing log files between scons runs which will show differences that are noisy and not actually significant. To disable, use the --cache-show option. With this option, scons changes printing to always show the action that would have been used to build the file without caching.

    Derived-file caching may be disabled for any invocation of scons by giving the --cache-disable command line option; cache updating may be disabled, leaving cache fetching enabled, by giving the --cache-readonly option.

    If the --cache-force option is used, scons will place a copy of all derived files into the cache, even if they already existed and were not built by this invocation. This is useful to populate a cache the first time a cache_dir is used for a build, or to bring a cache up to date after a build with cache updating disabled (--cache-disable or --cache-readonly) has been done.

    The NoCache method can be used to disable caching of specific files. This can be useful if inputs and/or outputs of some tool are impossible to predict or prohibitively large.

    Note that (at this time) SCons provides no facilities for managing the derived-file cache. It is up to the developer to arrange for cache pruning, expiry, access control, etc. if needed.

Clean(targets, files_or_dirs), env.Clean(targets, files_or_dirs)
    This specifies a list of files or directories which should be removed whenever the targets are specified with the -c command line option. The specified targets may be a list or an individual target. Multiple calls to Clean are legal, and create new targets or add files and directories to the clean list for the specified targets.

    Multiple files or directories should be specified either as separate arguments to the Clean method, or as a list. Clean will also accept the return value of any of the construction environment Builder methods. Examples:

    The related NoClean function overrides calling Clean for the same target, and any targets passed to both functions will not be removed by the -c option.

    Examples:

        Clean('foo', ['bar', 'baz'])
        Clean('dist', env.Program('hello', 'hello.c'))
        Clean(['foo', 'bar'], 'something_else_to_clean')

    In this example, installing the project creates a subdirectory for the documentation. This statement causes the subdirectory to be removed if the project is deinstalled.

        Clean(docdir, os.path.join(docdir, projectname))

env.Clone([key=val, ...])
    Returns an independent copy of a construction environment. If there are any unrecognized keyword arguments specified, they are added as construction variables in the copy, overwriting any existing values for those keywords. See the manpage section "Construction Environments" for more details.

    Example:

        env2 = env.Clone()
        env3 = env.Clone(CCFLAGS='-g')

    A list of tools and a toolpath may be specified, as in the Environment constructor:

        def MyTool(env):
            env['FOO'] = 'bar'
        env4 = env.Clone(tools=['msvc', MyTool])

    The parse_flags keyword argument is also recognized, to allow merging command-line style arguments into the appropriate construction variables (see env.MergeFlags).

        # create an environment for compiling programs that use wxWidgets
        wx_env = env.Clone(parse_flags='!wx-config --cflags --cxxflags')

    The variables keyword argument is also recognized, to allow (re)initializing construction variables from a Variables object.

    Changed in version 4.8.0: the variables parameter was added.

Command(target, source, action, [key=val, ...]), env.Command(target, source, action, [key=val, ...])
    Creates an anonymous builder and calls it, thus recording action to build target from source into the dependency tree. This can be more convenient for a single special-case build than having to define and add a new named Builder.

    The Command function accepts the source_scanner and target_scanner keyword arguments which are used to specify custom scanners for the specified sources or targets. The value must be a Scanner object. For example, the global DirScanner object can be used if any of the sources will be directories that must be scanned on-disk for changes to files that aren't already specified in other Builder or function calls.

    The Command function also accepts the source_factory and target_factory keyword arguments which are used to specify factory functions to create SCons Nodes from any sources or targets specified as strings. If any sources or targets are already Node objects, they are not further transformed even if a factory is specified for them. The default for each is the Entry factory.

    These four arguments, if given, are used in the creation of the Builder. Other Builder-specific keyword arguments are not recognized as such. See the manpage section "Builder Objects" for more information about how these arguments work in a Builder.

    Any remaining keyword arguments are passed on to the generated builder when it is called, and behave as described in the manpage section "Builder Methods", in short: recognized arguments have their specified meanings, while the rest are used to override any same-named existing construction variables from the construction environment.

    action can be an external command, specified as a string, or a callable Python object; see the manpage section "Action Objects" for more complete information. Also note that a string specifying an external command may be preceded by an at-sign (@) to suppress printing the command in question, or by a hyphen (-) to ignore the exit status of the external command.

    Examples:

        env.Command(
            target='foo.out',
            source='foo.in',
            action="$FOO_BUILD < $SOURCES > $TARGET"
        )
        env.Command(
            target='bar.out',
            source='bar.in',
            action=["rm -f $TARGET", "$BAR_BUILD < $SOURCES > $TARGET"],
            ENV={'PATH': '/usr/local/bin/'},
        )
        import os
        def rename(env, target, source):
            os.rename('.tmp', str(target[0]))
        env.Command(
            target='baz.out',
            source='baz.in',
            action=["$BAZ_BUILD < $SOURCES > .tmp", rename],
        )

    Note that the Command function will usually assume, by default, that the specified targets and/or sources are Files, if no other part of the configuration identifies what type of entries they are. If necessary, you can explicitly specify that targets or source nodes should be treated as directories by using the Dir or env.Dir functions.

    Examples:

        env.Command('ddd.list', Dir('ddd'), 'ls -l $SOURCE > $TARGET')
        env['DISTDIR'] = 'destination/directory'
        env.Command(env.Dir('$DISTDIR')), None, make_distdir)

    Also note that SCons will usually automatically create any directory necessary to hold a target file, so you normally don't need to create directories by hand.

Configure(env, [custom_tests, conf_dir, log_file, config_h]), env.Configure([custom_tests, conf_dir, log_file, config_h])
    Creates a Configure object for integrated functionality similar to GNU autoconf. See the manpage section "Configure Contexts" for a complete explanation of the arguments and behavior.

DebugOptions([json])
    Allows setting options for SCons debug options. Currently the only supported value is json which sets the path to the json file created when --debug=json is set.

        DebugOptions(json='#/build/output/scons_stats.json')

    New in version 4.6.0.

Decider(function), env.Decider(function)
    Specifies that all up-to-date decisions for targets built through this construction environment will be handled by the specified function. function can be the name of a function or one of the following strings that specify the predefined decision function that will be applied:

    "content"
        Specifies that a target shall be considered out of date and rebuilt if the dependency's content has changed since the last time the target was built, as determined by performing a checksum on the dependency's contents using the selected hash function, and comparing it to the checksum recorded the last time the target was built. content is the default decider.

        Changed in version 4.1: The decider was renamed to content since the hash function is now selectable. The former name, MD5, can still be used as a synonym, but is deprecated.

    "content-timestamp"
        Specifies that a target shall be considered out of date and rebuilt if the dependency's content has changed since the last time the target was built, except that dependencies with a timestamp that matches the last time the target was rebuilt will be assumed to be up-to-date and not rebuilt. This provides behavior very similar to the content behavior of always checksumming file contents, with an optimization of not checking the contents of files whose timestamps haven't changed. The drawback is that SCons will not detect if a file's content has changed but its timestamp is the same, as might happen in an automated script that runs a build, updates a file, and runs the build again, all within a single second.

        Changed in version 4.1: The decider was renamed to content-timestamp since the hash function is now selectable. The former name, MD5-timestamp, can still be used as a synonym, but is deprecated.

    "timestamp-newer"
        Specifies that a target shall be considered out of date and rebuilt if the dependency's timestamp is newer than the target file's timestamp. This is the behavior of the classic Make utility, and make can be used a synonym for timestamp-newer.

    "timestamp-match"
        Specifies that a target shall be considered out of date and rebuilt if the dependency's timestamp is different than the timestamp recorded the last time the target was built. This provides behavior very similar to the classic Make utility (in particular, files are not opened up so that their contents can be checksummed) except that the target will also be rebuilt if a dependency file has been restored to a version with an earlier timestamp, such as can happen when restoring files from backup archives.

    Examples:

        # Use exact timestamp matches by default.
        Decider('timestamp-match')
        # Use hash content signatures for any targets built
        # with the attached construction environment.
        env.Decider('content')

    In addition to the above already-available functions, the function argument may be a Python function you supply. Such a function must accept the following four arguments:

    dependency
        The Node (file) which should cause the target to be rebuilt if it has "changed" since the last tme target was built.

    target
        The Node (file) being built. In the normal case, this is what should get rebuilt if the dependency has "changed."

    prev_ni
        Stored information about the state of the dependency the last time the target was built. This can be consulted to match various file characteristics such as the timestamp, size, or content signature.

    repo_node
        If set, use this Node instead of the one specified by dependency to determine if the dependency has changed. This argument is optional so should be written as a default argument (typically it would be written as repo_node=None). A caller will normally only set this if the target only exists in a Repository.

    The function should return a value which evaluates True if the dependency has "changed" since the last time the target was built (indicating that the target should be rebuilt), and a value which evaluates False otherwise (indicating that the target should not be rebuilt). Note that the decision can be made using whatever criteria are appopriate. Ignoring some or all of the function arguments is perfectly normal.

    Example:

        def my_decider(dependency, target, prev_ni, repo_node=None):
            return not os.path.exists(str(target))
        env.Decider(my_decider)

Default(target[, ...]), env.Default(target[, ...])
    Specify default targets to the SCons target selection mechanism. Any call to Default will cause SCons to use the defined default target list instead of its built-in algorithm for determining default targets (see the manpage section "Target Selection").

    target may be one or more strings, a list of strings, a NodeList as returned by a Builder, or None. A string target may be the name of a file or directory, or a target previously defined by a call to Alias (defining the alias later will still create the alias, but it will not be recognized as a default). Calls to Default are additive. A target of None will clear any existing default target list; subsequent calls to Default will add to the (now empty) default target list like normal.

    Both forms of this call affect the same global list of default targets; the construction environment method applies construction variable expansion to the targets.

    The current list of targets added using Default is available in the DEFAULT_TARGETS list (see below).

    Examples:

        Default('foo', 'bar', 'baz')
        env.Default(['a', 'b', 'c'])
        hello = env.Program('hello', 'hello.c')
        env.Default(hello)

DefaultEnvironment([key=value, ...])
    Instantiates and returns the global construction environment object. The Default Environment is used internally by SCons when executing a global function or the global form of a Builder method that requires access to a construction environment.

    On the first call, arguments are interpreted as for the Environment function. The Default Environment is a singleton; subsequent calls to DefaultEnvironment return the already-constructed object, and any keyword arguments are silently ignored.

    The Default Environment can be modified after instantiation, similar to other construction environments, although some construction environment methods may be unavailable. Modifying the Default Environment has no effect on any other construction environment, either existing or newly constructed.

    It is not necessary to explicitly call DefaultEnvironment. SCons instantiates the default environment automatically when the build phase begins, if has not already been done. However, calling it explicitly provides the opportunity to affect and examine its contents. Instantiation occurs even if nothing in the build system appars to use it, due to internal uses.

    If the project SConscript files do not use global functions or Builders, a small performance gain may be achieved by calling DefaultEnvironment with an empty tools list (DefaultEnvironment(tools=[])). This avoids the tool initialization cost for the Default Environment, which is mainly of interest in the test suite where scons is launched repeatedly in a short time period.

Depends(target, dependency), env.Depends(target, dependency)
    Specifies an explicit dependency; the target will be rebuilt whenever the dependency has changed. Both the specified target and dependency can be a string (usually the path name of a file or directory) or Node objects, or a list of strings or Node objects (such as returned by a Builder call). This should only be necessary for cases where the dependency is not caught by a Scanner for the file.

    Example:

        env.Depends('foo', 'other-input-file-for-foo')
        mylib = env.Library('mylib.c')
        installed_lib = env.Install('lib', mylib)
        bar = env.Program('bar.c')
        # Arrange for the library to be copied into the installation
        # directory before trying to build the "bar" program.
        # (Note that this is for example only.  A "real" library
        # dependency would normally be configured through the $LIBS
        # and $LIBPATH variables, not using an env.Depends() call.)
        env.Depends(bar, installed_lib)

env.Detect(progs)
    Find an executable from one or more choices: progs may be a string or a list of strings. Returns the first value from progs that was found, or None. Executable is searched by checking the paths in the execution environment (env['ENV']['PATH']). On Windows systems, additionally applies the filename suffixes found in the execution environment (env['ENV']['PATHEXT']) but will not include any such extension in the return value. env.Detect is a wrapper around env.WhereIs.

env.Dictionary([vars])
    Returns a dictionary object containing the construction variables in the construction environment. If there are any arguments specified, the values of the specified construction variables are returned as a string (if one argument) or as a list of strings.

    Example:

        cvars = env.Dictionary()
        cc_values = env.Dictionary('CC', 'CCFLAGS', 'CCCOM')

Dir(name, [directory]), env.Dir(name, [directory])
    Returns Directory Node(s). A Directory Node is an object that represents a directory. name can be a relative or absolute path or a list of such paths. directory is an optional directory that will be used as the parent directory. If no directory is specified, the current script's directory is used as the parent.

    If name is a single pathname, the corresponding node is returned. If name is a list, SCons returns a list of nodes. Construction variables are expanded in name.

    Directory Nodes can be used anywhere you would supply a string as a directory name to a Builder method or function. Directory Nodes have attributes and methods that are useful in many situations; see manpage section "Filesystem Nodes" for more information.

env.Dump([key, ...], [format=])
    Serializes construction variables from the current construction environment to a string. The method supports the following formats specified by format, which must be used a a keyword argument:

    pretty
        Returns a pretty-printed representation of the variables (this is the default). The variables will be presented in Python dict form.

    json
        Returns a JSON-formatted string representation of the variables. The variables will be presented as a JSON object literal, the JSON equivalent of a Python dict.

    If no key is supplied, all the construction variables are serialized. If one or more keys are supplied, only those keys and their values are serialized.

    Changed in NEXT_VERSION: More than one key can be specified. The returned string always looks like a dict (or JSON equivalent); previously a single key serialized only the value, not the key with the value.

    This SConstruct:

        env = Environment()
        print(env.Dump('CCCOM'))
        print(env.Dump('CC', 'CCFLAGS', format='json'))

    will print something like:

        {'CCCOM': '$CC -o $TARGET -c $CFLAGS $CCFLAGS $_CCCOMCOM $SOURCES'}
        {
            "CC": "gcc",
            "CCFLAGS": []
        }

    While this SConstruct:

        env = Environment()
        print(env.Dump())

    will print something like:

        { 'AR': 'ar',
          'ARCOM': '$AR $ARFLAGS $TARGET $SOURCES\n$RANLIB $RANLIBFLAGS $TARGET',
          'ARFLAGS': ['r'],
          'AS': 'as',
          'ASCOM': '$AS $ASFLAGS -o $TARGET $SOURCES',
          'ASFLAGS': [],
          ...

EnsurePythonVersion(major, minor)
    Ensure that the Python version is at least major.minor. This function will print out an error message and exit SCons with a non-zero exit code if the actual Python version is not late enough.

    Example:

        EnsurePythonVersion(2,2)

EnsureSConsVersion(major, minor, [revision])
    Ensure that the SCons version is at least major.minor, or major.minor.revision. if revision is specified. This function will print out an error message and exit SCons with a non-zero exit code if the actual SCons version is not late enough.

    Examples:

        EnsureSConsVersion(0,14)
        EnsureSConsVersion(0,96,90)

Environment([key=value, ...]), env.Environment([key=value, ...])
    Return a new construction environment initialized with the specified key=value pairs. The keyword arguments parse_flags, platform, toolpath, tools and variables are specially recognized and do not lead to construction variable creation. See the manpage section "Construction Environments" for more details.

Execute(action, [actionargs ...]), env.Execute(action, [actionargs ...])
    Executes an Action. action may be an Action object or it may be a command-line string, list of commands, or executable Python function, each of which will first be converted into an Action object and then executed. Any additional arguments to Execute are passed on to the Action factory function which actually creates the Action object (see the manpage section Action Objects for a description). Example:

        Execute(Copy('file.out', 'file.in'))

    Execute performs its action immediately, as part of the SConscript-reading phase. There are no sources or targets declared in an Execute call, so any objects it manipulates will not be tracked as part of the SCons dependency graph. In the example above, neither file.out nor file.in will be tracked objects.

    Execute returns the exit value of the command or return value of the Python function. scons prints an error message if the executed action fails (exits with or returns a non-zero value), however it does not, automatically terminate the build for such a failure. If you want the build to stop in response to a failed Execute call, you must explicitly check for a non-zero return value:

        if Execute("mkdir sub/dir/ectory"):
            # The mkdir failed, don't try to build.
            Exit(1)

Exit([value])
    This tells scons to exit immediately with the specified value. A default exit value of 0 (zero) is used if no value is specified.

Export([vars...], [key=value...]), env.Export([vars...], [key=value...])
    Exports variables for sharing with other SConscript files. The variables are added to a global collection where they can be imported by other SConscript files. vars may be one or more strings, or a list of strings. If any string contains whitespace, it is split automatically into individual strings. Each string must match the name of a variable that is in scope during evaluation of the current SConscript file, or an exception is raised.

    A vars argument may also be a dictionary or individual keyword arguments; in accordance with Python syntax rules, keyword arguments must come after any non-keyword arguments. The dictionary/keyword form can be used to map the local name of a variable to a different name to be used for imports. See the Examples for an illustration of the syntax.

    Export calls are cumulative. Specifying a previously exported variable will replace the previous value in the collection. Both local variables and global variables can be exported.

    To use an exported variable, an SConscript must call Import to bring it into its own scope. Importing creates an additional reference to the object that was originally exported, so if that object is mutable, changes made will be visible to other users of that object.

    Examples:

        env = Environment()
        # Make env available for all SConscript files to Import().
        Export("env")
        package = 'my_name'
        # Make env and package available for all SConscript files:.
        Export("env", "package")
        # Make env and package available for all SConscript files:
        Export(["env", "package"])
        # Make env available using the name debug:
        Export(debug=env)
        # Make env available using the name debug:
        Export({"debug": env})

    Note that the SConscript function also supports an exports argument that allows exporting one or more variables to the SConscript files invoked by that call (only). See the description of that function for details.

File(name, [directory]), env.File(name, [directory])
    Returns File Node(s). A File Node is an object that represents a file. name can be a relative or absolute path or a list of such paths. directory is an optional directory that will be used as the parent directory. If no directory is specified, the current script's directory is used as the parent.

    If name is a single pathname, the corresponding node is returned. If name is a list, SCons returns a list of nodes. Construction variables are expanded in name.

    File Nodes can be used anywhere you would supply a string as a file name to a Builder method or function. File Nodes have attributes and methods that are useful in many situations; see manpage section "Filesystem Nodes" for more information.

FindFile(file, dirs), env.FindFile(file, dirs)
    Search for file in the path specified by dirs. dirs may be a list of directory names or a single directory name. In addition to searching for files that exist in the filesystem, this function also searches for derived files that have not yet been built.

    Example:

        foo = env.FindFile('foo', ['dir1', 'dir2'])

FindInstalledFiles(), env.FindInstalledFiles()
    Returns the list of targets set up by the Install or InstallAs builders.

    This function serves as a convenient method to select the contents of a binary package.

    Example:

        Install('/bin', ['executable_a', 'executable_b'])
        # will return the file node list
        # ['/bin/executable_a', '/bin/executable_b']
        FindInstalledFiles()
        Install('/lib', ['some_library'])
        # will return the file node list
        # ['/bin/executable_a', '/bin/executable_b', '/lib/some_library']
        FindInstalledFiles()

FindPathDirs(variable)
    Returns a function (actually a callable Python object) intended to be used as the path_function of a Scanner object. The returned object will look up the specified variable in a construction environment and treat the construction variable's value as a list of directory paths that should be searched (like $CPPPATH, $LIBPATH, etc.).

    Note that use of FindPathDirs is generally preferable to writing your own path_function for the following reasons: 1) The returned list will contain all appropriate directories found in source trees (when VariantDir is used) or in code repositories (when Repository or the -Y option are used). 2) scons will identify expansions of variable that evaluate to the same list of directories as, in fact, the same list, and avoid re-scanning the directories for files, when possible.

    Example:

        def my_scan(node, env, path, arg):
            # Code to scan file contents goes here...
            return include_files
        scanner = Scanner(name = 'myscanner',
                          function = my_scan,
                          path_function = FindPathDirs('MYPATH'))

FindSourceFiles(node='"."'), env.FindSourceFiles(node='"."')
    Returns the list of nodes which serve as the source of the built files. It does so by inspecting the dependency tree starting at the optional argument node which defaults to the '"."'-node. It will then return all leaves of node. These are all children which have no further children.

    This function is a convenient method to select the contents of a Source Package.

    Example:

        Program('src/main_a.c')
        Program('src/main_b.c')
        Program('main_c.c')
        # returns ['main_c.c', 'src/main_a.c', 'SConstruct', 'src/main_b.c']
        FindSourceFiles()
        # returns ['src/main_b.c', 'src/main_a.c' ]
        FindSourceFiles('src')

    As you can see build support files (SConstruct in the above example) will also be returned by this function.

Flatten(sequence), env.Flatten(sequence)
    Takes a sequence (that is, a Python list or tuple) that may contain nested sequences and returns a flattened list containing all of the individual elements in any sequence. This can be helpful for collecting the lists returned by calls to Builders; other Builders will automatically flatten lists specified as input, but direct Python manipulation of these lists does not.

    Examples:

        foo = Object('foo.c')
        bar = Object('bar.c')
        # Because `foo' and `bar' are lists returned by the Object() Builder,
        # `objects' will be a list containing nested lists:
        objects = ['f1.o', foo, 'f2.o', bar, 'f3.o']
        # Passing such a list to another Builder is all right because
        # the Builder will flatten the list automatically:
        Program(source = objects)
        # If you need to manipulate the list directly using Python, you need to
        # call Flatten() yourself, or otherwise handle nested lists:
        for object in Flatten(objects):
            print(str(object))

GetBuildFailures()
    Returns a list of exceptions for the actions that failed while attempting to build targets. Each element in the returned list is a BuildError object with the following attributes that record various aspects of the build failure:

    .node The node that was being built when the build failure occurred.

    .status The numeric exit status returned by the command or Python function that failed when trying to build the specified Node.

    .errstr The SCons error string describing the build failure. (This is often a generic message like "Error 2" to indicate that an executed command exited with a status of 2.)

    .filename The name of the file or directory that actually caused the failure. This may be different from the .node attribute. For example, if an attempt to build a target named sub/dir/target fails because the sub/dir directory could not be created, then the .node attribute will be sub/dir/target but the .filename attribute will be sub/dir.

    .executor The SCons Executor object for the target Node being built. This can be used to retrieve the construction environment used for the failed action.

    .action The actual SCons Action object that failed. This will be one specific action out of the possible list of actions that would have been executed to build the target.

    .command The actual expanded command that was executed and failed, after expansion of $TARGET, $SOURCE, and other construction variables.

    Note that the GetBuildFailures function will always return an empty list until any build failure has occurred, which means that GetBuildFailures will always return an empty list while the SConscript files are being read. Its primary intended use is for functions that will be executed before SCons exits by passing them to the standard Python atexit.register() function. Example:

        import atexit
        def print_build_failures():
            from SCons.Script import GetBuildFailures
            for bf in GetBuildFailures():
                print("%s failed: %s" % (bf.node, bf.errstr))
        atexit.register(print_build_failures)

GetBuildPath(file, [...]), env.GetBuildPath(file, [...])
    Returns the scons path name (or names) for the specified file (or files). The specified file or files may be scons Nodes or strings representing path names.

GetLaunchDir()
    Returns the absolute path name of the directory from which scons was initially invoked. This can be useful when using the -u, -U or -D options, which internally change to the directory in which the SConstruct file is found.

GetOption(name), env.GetOption(name)
    Query the value of settable options which may have been set on the command line, via option defaults, or by using the SetOption function. The value of the option is returned in a type matching how the option was declared - see the documentation of the corresponding command line option for information about each specific option.

    name can be an entry from the following table, which shows the corresponding command line arguments that could affect the value. name can be also be the destination variable name from a project-specific option added using the AddOption function, as long as that addition has been processed prior to the GetOption call in the SConscript files.
    Query name | Command-line options | Notes
    cache_debug | --cache-debug |
    cache_disable | --cache-disable, --no-cache |
    cache_force | --cache-force, --cache-populate |
    cache_readonly | --cache-readonly |
    cache_show | --cache-show |
    clean | -c, --clean, --remove |
    climb_up | -D -U -u --up --search_up |
    config | --config |
    debug | --debug |
    directory | -C, --directory |
    diskcheck | --diskcheck |
    duplicate | --duplicate |
    enable_virtualenv | --enable-virtualenv |
    experimental | --experimental | since 4.2
    file | -f, --file, --makefile, --sconstruct |
    hash_format | --hash-format | since 4.2
    help | -h, --help |
    ignore_errors | -i, --ignore-errors |
    ignore_virtualenv | --ignore-virtualenv |
    implicit_cache | --implicit-cache |
    implicit_deps_changed | --implicit-deps-changed |
    implicit_deps_unchanged | --implicit-deps-unchanged |
    include_dir | -I, --include-dir |
    install_sandbox | --install-sandbox | Available only if the install tool has been called
    keep_going | -k, --keep-going |
    max_drift | --max-drift |
    md5_chunksize | --hash-chunksize, --md5-chunksize | --hash-chunksize since 4.2
    no_exec | -n, --no-exec, --just-print, --dry-run, --recon |
    no_progress | -Q |
    num_jobs | -j, --jobs |
    package_type | --package-type | Available only if the packaging tool has been called
    profile_file | --profile |
    question | -q, --question |
    random | --random |
    repository | -Y, --repository, --srcdir |
    silent | -s, --silent, --quiet |
    site_dir | --site-dir, --no-site-dir |
    stack_size | --stack-size |
    taskmastertrace_file | --taskmastertrace |
    tree_printers | --tree |
    warn | --warn, --warning |

GetSConsVersion()
    Returns the current SCons version in the form of a Tuple[int, int, int], representing the major, minor, and revision values respectively. Added in 4.8.0.

Glob(pattern, [ondisk=True, source=False, strings=False, exclude=None]), env.Glob(pattern, [ondisk=True, source=False, strings=False, exclude=None])
    Returns a possibly empty list of Nodes (or strings) that match pathname specification pattern. pattern can be absolute, top-relative, or (most commonly) relative to the directory of the current SConscript file. Glob matches both files stored on disk and Nodes which SCons already knows about, even if any corresponding file is not currently stored on disk. The evironment method form (env.Glob) performs string substition on pattern and returns whatever matches the resulting expanded pattern. The results are sorted, unlike for the similar Python glob.glob function, to ensure build order will be stable.

    pattern can contain POSIX-style shell metacharacters for matching:
    Pattern | Meaning
    * | matches everything
    ? | matches any single character
    [seq] | matches any character in seq (can be a list or a range).
    [!seq] | matches any character not in seq

    For a literal match, wrap the metacharacter in brackets to escape the normal behavior. For example, '[?]' matches the character '?'.

    Filenames starting with a dot are specially handled - they can only be matched by patterns that start with a dot (or have a dot immediately following a pathname separator character, or slash), they are not not matched by the metacharacters. Metacharacter matches also do not span directory separators.

    Glob understands repositories (see the Repository function) and source directories (see the VariantDir function) and returns a Node (or string, if so configured) match in the local (SConscript) directory if a matching Node is found anywhere in a corresponding repository or source directory.

    If the optional ondisk argument evaluates false, the search for matches on disk is disabled, and only matches from already-configured File or Dir Nodes are returned. The default is to return Nodes for matches on disk as well.

    If the optional source argument evaluates true, and the local directory is a variant directory, then Glob returnes Nodes from the corresponding source directory, rather than the local directory.

    If the optional strings argument evaluates true, Glob returns matches as strings, rather than Nodes. The returned strings will be relative to the local (SConscript) directory. (Note that while this may make it easier to perform arbitrary manipulation of file names, it loses the context SCons would have in the Node, so if the returned strings are passed to a different SConscript file, any Node translation there will be relative to that SConscript directory, not to the original SConscript directory.)

    The optional exclude argument may be set to a pattern or a list of patterns descibing files or directories to filter out of the match list. Elements matching a least one specified pattern will be excluded. These patterns use the same syntax as for pattern.

    Examples:

        Program("foo", Glob("*.c"))
        Zip("/tmp/everything", Glob(".??*") + Glob("*"))
        sources = Glob("*.cpp", exclude=["os_*_specific_*.cpp"]) \
            + Glob("os_%s_specific_*.cpp" % currentOS)

Help(text, append=False, local_only=False), env.Help(text, append=False, local_only=False)
    Adds text to the help message shown when scons is called with the -h or --help argument.

    On the first call to Help, if append is False (the default), any existing help text is discarded. The default help text is the help for the scons command itself plus help collected from any project-local AddOption calls. This is the help printed if Help has never been called. If append is True, text is appended to the existing help text. If local_only is also True (the default is False), the project-local help from AddOption calls is preserved in the help message but the scons command help is not.

    Subsequent calls to Help ignore the keyword arguments append and local_only and always append to the existing help text.

    Changed in 4.6.0: added local_only.

Ignore(target, dependency), env.Ignore(target, dependency)
    Ignores dependency when deciding if target needs to be rebuilt. target and dependency can each be a single filename or Node or a list of filenames or Nodes.

    Ignore can also be used to remove a target from the default build by specifying the directory the target will be built in as target and the file you want to skip selecting for building as dependency. Note that this only removes the target from the default target selection algorithm: if it is a dependency of another object being built SCons still builds it normally. See the third and forth examples below.

    Examples:

        env.Ignore('foo', 'foo.c')
        env.Ignore('bar', ['bar1.h', 'bar2.h'])
        env.Ignore('.', 'foobar.obj')
        env.Ignore('bar', 'bar/foobar.obj')

Import(vars...), env.Import(vars...)
    Imports variables into the scope of the current SConscript file. vars must be strings representing names of variables which have been previously exported either by the Export function or by the exports argument to the SConscript function. Variables exported by the SConscript call take precedence. Multiple variable names can be passed to Import as separate arguments, as a list of strings, or as words in a space-separated string. The wildcard "*" can be used to import all available variables.

    If the imported variable is mutable, changes made locally will be reflected in the object the variable is bound to. This allows subsidiary SConscript files to contribute to building up, for example, a construction environment.

    Examples:

        Import("env")
        Import("env", "variable")
        Import(["env", "variable"])
        Import("*")

Literal(string), env.Literal(string)
    The specified string will be preserved as-is and not have construction variables expanded.

Local(targets), env.Local(targets)
    The specified targets will have copies made in the local tree, even if an already up-to-date copy exists in a repository. Returns a list of the target Node or Nodes.

env.MergeFlags(arg, [unique])
    Merges values from arg into construction variables in env. If arg is a dictionary, each key-value pair represents a construction variable name and the corresponding flags to merge. If arg is not a dictionary, MergeFlags attempts to convert it to one before the values are merged. env.ParseFlags is used for this, so values to be converted are subject to the same limitations: ParseFlags has knowledge of which construction variables certain flags should go to, but not all; and only for GCC and compatible compiler chains. arg must be a single object, so to pass multiple strings, enclose them in a list.

    If unique is true (the default), duplicate values are not retained. In case of duplication, any construction variable names that end in PATH keep the left-most value so the path searcb order is not altered. All other construction variables keep the right-most value. If unique is false, values are appended even if they are duplicates.

    Examples:

        # Add an optimization flag to $CCFLAGS.
        env.MergeFlags({'CCFLAGS': '-O3'})
        # Combine the flags returned from running pkg-config with an optimization
        # flag and merge the result into the construction variables.
        env.MergeFlags(['!pkg-config gtk+-2.0 --cflags', '-O3'])
        # Combine an optimization flag with the flags returned from running pkg-config
        # for two distinct packages and merge into the construction variables.
        env.MergeFlags(
            [
                '-O3',
                '!pkg-config gtk+-2.0 --cflags --libs',
                '!pkg-config libpng12 --cflags --libs',
            ]
        )

NoCache(target, ...), env.NoCache(target, ...)
    Specifies a list of files which should not be cached whenever the CacheDir method has been activated. The specified targets may be a list or an individual target.

    Multiple files should be specified either as separate arguments to the NoCache method, or as a list. NoCache will also accept the return value of any of the construction environment Builder methods.

    Calling NoCache on directories and other non-File Node types has no effect because only File Nodes are cached.

    Examples:

        NoCache('foo.elf')
        NoCache(env.Program('hello', 'hello.c'))

NoClean(target, ...), env.NoClean(target, ...)
    Specifies a list of files or directories which should not be removed whenever the targets (or their dependencies) are specified with the -c command line option. The specified targets may be a list or an individual target. Multiple calls to NoClean are legal, and prevent each specified target from being removed by calls to the -c option.

    Multiple files or directories should be specified either as separate arguments to the NoClean method, or as a list. NoClean will also accept the return value of any of the construction environment Builder methods.

    Calling NoClean for a target overrides calling Clean for the same target, and any targets passed to both functions will not be removed by the -c option.

    Examples:

        NoClean('foo.elf')
        NoClean(env.Program('hello', 'hello.c'))

env.ParseConfig(command, [function, unique])
    Updates the current construction environment with the values extracted from the output of running external command, by passing it to a helper function. command may be a string or a list of strings representing the command and its arguments. If function is omitted or None, env.MergeFlags is used. By default, duplicate values are not added to any construction variables; you can specify unique=False to allow duplicate values to be added.

    command is executed using the SCons execution environment (that is, the construction variable $ENV in the current construction environment). If command needs additional information to operate properly, that needs to be set in the execution environment. For example, pkg-config may need a custom value set in the PKG_CONFIG_PATH environment variable.

    env.MergeFlags needs to understand the output produced by command in order to distribute it to appropriate construction variables. env.MergeFlags uses a separate function to do that processing - see env.ParseFlags for the details, including a a table of options and corresponding construction variables. To provide alternative processing of the output of command, you can suppply a custom function, which must accept three arguments: the construction environment to modify, a string argument containing the output from running command, and the optional unique flag.

ParseDepends(filename, [must_exist, only_one]), env.ParseDepends(filename, [must_exist, only_one])
    Parses the contents of filename as a list of dependencies in the style of Make or mkdep, and explicitly establishes all of the listed dependencies.

    By default, it is not an error if filename does not exist. The optional must_exist argument may be set to True to have SCons raise an exception if the file does not exist, or is otherwise inaccessible.

    The optional only_one argument may be set to True to have SCons raise an exception if the file contains dependency information for more than one target. This can provide a small sanity check for files intended to be generated by, for example, the gcc -M flag, which should typically only write dependency information for one output file into a corresponding .d file.

    filename and all of the files listed therein will be interpreted relative to the directory of the SConscript file which calls the ParseDepends function.

env.ParseFlags(flags, ...)
    Parses one or more strings containing typical command-line flags for GCC-style tool chains and returns a dictionary with the flag values separated into the appropriate SCons construction variables. Intended as a companion to the env.MergeFlags method, but allows for the values in the returned dictionary to be modified, if necessary, before merging them into the construction environment. (Note that env.MergeFlags will call this method if its argument is not a dictionary, so it is usually not necessary to call env.ParseFlags directly unless you want to manipulate the values.)

    If the first character in any string is an exclamation mark (!), the rest of the string is executed as a command, and the output from the command is parsed as GCC tool chain command-line flags and added to the resulting dictionary. This can be used to call a *-config command typical of the POSIX programming environment (for example, pkg-config). Note that such a command is executed using the SCons execution environment; if the command needs additional information, that information needs to be explicitly provided. See ParseConfig for more details.

    Flag values are translated according to the prefix found, and added to the following construction variables:

        -arch                   CCFLAGS, LINKFLAGS
        -D                      CPPDEFINES
        -framework              FRAMEWORKS
        -frameworkdir=          FRAMEWORKPATH
        -fmerge-all-constants   CCFLAGS, LINKFLAGS
        -fopenmp                CCFLAGS, LINKFLAGS
        -fsanitize              CCFLAGS, LINKFLAGS
        -include                CCFLAGS
        -imacros                CCFLAGS
        -isysroot               CCFLAGS, LINKFLAGS
        -isystem                CCFLAGS
        -iquote                 CCFLAGS
        -idirafter              CCFLAGS
        -I                      CPPPATH
        -l                      LIBS
        -L                      LIBPATH
        -mno-cygwin             CCFLAGS, LINKFLAGS
        -mwindows               LINKFLAGS
        -openmp                 CCFLAGS, LINKFLAGS
        -pthread                CCFLAGS, LINKFLAGS
        -std=                   CFLAGS
        -stdlib=                CXXFLAGS
        -Wa,                    ASFLAGS, CCFLAGS
        -Wl,-rpath=             RPATH
        -Wl,-R,                 RPATH
        -Wl,-R                  RPATH
        -Wl,                    LINKFLAGS
        -Wp,                    CPPFLAGS
        -                       CCFLAGS
        +                       CCFLAGS, LINKFLAGS

    Any other strings not associated with options are assumed to be the names of libraries and added to the $LIBS construction variable.

    Examples (all of which produce the same result):

        dict = env.ParseFlags('-O2 -Dfoo -Dbar=1')
        dict = env.ParseFlags('-O2', '-Dfoo', '-Dbar=1')
        dict = env.ParseFlags(['-O2', '-Dfoo -Dbar=1'])
        dict = env.ParseFlags('-O2', '!echo -Dfoo -Dbar=1')

Platform(plat), env.Platform(plat)
    When called as a global function, returns a callable platform object selected by plat (defaults to the detected platform for the current system) that can be used to initialize a construction environment by passing it as the platform keyword argument to the Environment function.

    Example:

        env = Environment(platform=Platform('win32'))

    When called as a method of an environment, calls the platform object indicated by plat to update that environment.

        env.Platform('posix')

    See the manpage section "Construction Environments" for more details.

Precious(target, ...), env.Precious(target, ...)
    Marks target as precious so it is not deleted before it is rebuilt. Normally SCons deletes a target before building it. Multiple targets can be passed in a single call, and may be strings and/or nodes. Returns a list of the affected target nodes.

env.Prepend(key=val, [...])
    Prepend values to construction variables in the current construction environment, Works like env.Append (see for details), except that values are added to the front, rather than the end, of any existing value of the construction variable

    Example:

        env.Prepend(CCFLAGS='-g ', FOO=['foo.yyy'])

    See also env.Append, env.AppendUnique and env.PrependUnique.

env.PrependENVPath(name, newpath, [envname, sep, delete_existing=True])
    Prepend path elements specified by newpath to the given search path string or list name in mapping envname in the construction environment. Supplying envname is optional: the default is the execution environment $ENV. Optional sep is used as the search path separator, the default is the platform's separator (os.pathsep). A path element will only appear once. Any duplicates in newpath are dropped, keeping the first appearing (to preserve path order). If delete_existing is False any addition duplicating an existing path element is ignored; if delete_existing is True (the default) the existing value will be dropped and the path element will be inserted at the beginning. To help maintain uniqueness all paths are normalized (using os.path.normpath and os.path.normcase).

    Example:

        print('before:', env['ENV']['INCLUDE'])
        include_path = '/foo/bar:/foo'
        env.PrependENVPath('INCLUDE', include_path)
        print('after:', env['ENV']['INCLUDE'])

    Yields:

        before: /biz:/foo
        after: /foo/bar:/foo:/biz

    See also env.AppendENVPath.

env.PrependUnique(key=val, [...], [delete_existing=False])
    Prepend values to construction variables in the current construction environment, maintaining uniqueness. Works like env.Append, except that values are added to the front, rather than the end, of the construction variable, and values that would become duplicates are not added. If delete_existing is set to a true value, then for any duplicate, the existing instance of val is first removed, then val is inserted, having the effect of moving it to the front.

    Example:

        env.PrependUnique(CCFLAGS='-g', FOO=['foo.yyy'])

    See also env.Append, env.AppendUnique and env.Prepend.

Progress(callable, [interval]), Progress(string, [interval, file, overwrite]), Progress(list_of_strings, [interval, file, overwrite])
    Allows SCons to show progress made during the build by displaying a string or calling a function while evaluating Nodes (e.g. files).

    If the first specified argument is a Python callable (a function or an object that has a __call__ method), the function will be called once every interval times a Node is evaluated (default 1). The callable will be passed the evaluated Node as its only argument. (For future compatibility, it's a good idea to also add *args and **kwargs as arguments to your function or method signatures. This will prevent the code from breaking if SCons ever changes the interface to call the function with additional arguments in the future.)

    An example of a simple custom progress function that prints a string containing the Node name every 10 Nodes:

        def my_progress_function(node, *args, **kwargs):
            print('Evaluating node %s!' % node)
        Progress(my_progress_function, interval=10)

    A more complicated example of a custom progress display object that prints a string containing a count every 100 evaluated Nodes. Note the use of \r (a carriage return) at the end so that the string will overwrite itself on a display:

        import sys
        class ProgressCounter(object):
            count = 0
            def __call__(self, node, *args, **kw):
                self.count += 100
                sys.stderr.write('Evaluated %s nodes\r' % self.count)
        Progress(ProgressCounter(), interval=100)

    If the first argument to Progress is a string or list of strings, it is taken as text to be displayed every interval evaluated Nodes. If the first argument is a list of strings, then each string in the list will be displayed in rotating fashion every interval evaluated Nodes.

    The default is to print the string on standard output. An alternate output stream may be specified with the file keyword argument, which the caller must pass already opened.

    The following will print a series of dots on the error output, one dot for every 100 evaluated Nodes:

        import sys
        Progress('.', interval=100, file=sys.stderr)

    If the string contains the verbatim substring $TARGET;, it will be replaced with the Node. Note that, for performance reasons, this is not a regular SCons variable substition, so you can not use other variables or use curly braces. The following example will print the name of every evaluated Node, using a carriage return) (\r) to cause each line to overwritten by the next line, and the overwrite keyword argument (default False) to make sure the previously-printed file name is overwritten with blank spaces:

        import sys
        Progress('$TARGET\r', overwrite=True)

    A list of strings can be used to implement a "spinner" on the user's screen as follows, changing every five evaluated Nodes:

        Progress(['-\r', '\\\r', '|\r', '/\r'], interval=5)

Pseudo(target, ...), env.Pseudo(target, ...)
    Marks target as a pseudo target, not representing the production of any physical target file. If any pseudo target does exist, SCons will abort the build with an error. Multiple targets can be passed in a single call, and may be strings and/or Nodes. Returns a list of the affected target nodes.

    Pseudo may be useful in conjuction with a builder call (such as Command) which does not create a physical target, and the behavior if the target accidentally existed would be incorrect. This is similar in concept to the GNU make .PHONY target. SCons also provides a powerful target alias capability (see Alias) which may provide more flexibility in many situations when defining target names that are not directly built.

PyPackageDir(modulename), env.PyPackageDir(modulename)
    Finds the location of modulename, which can be a string or a sequence of strings, each representing the name of a Python module. Construction variables are expanded in modulename. Returns a Directory Node (see Dir), or a list of Directory Nodes if modulename is a sequence. None is returned for any module not found.

    When a Tool module which is installed as a Python module is used, you need to specify a toolpath argument to Tool, Environment or Clone, as tools outside the standard project locations (site_scons/site_tools) will not be found otherwise. Using PyPackageDir allows this path to be discovered at runtime instead of hardcoding the path.

    Example:

        env = Environment(
            tools=["default", "ExampleTool"],
            toolpath=[PyPackageDir("example_tool")]
        )

env.Replace(key=val, [...])
    Replaces construction variables in the Environment with the specified keyword arguments.

    Example:

        env.Replace(CCFLAGS='-g', FOO='foo.xxx')

Repository(directory), env.Repository(directory)
    Specifies that directory is a repository to be searched for files. Multiple calls to Repository are legal, and each one adds to the list of repositories that will be searched.

    To scons, a repository is a copy of the source tree, from the top-level directory on down, which may contain both source files and derived files that can be used to build targets in the local source tree. The canonical example would be an official source tree maintained by an integrator. If the repository contains derived files, then the derived files should have been built using scons, so that the repository contains the necessary signature information to allow scons to figure out when it is appropriate to use the repository copy of a derived file, instead of building one locally.

    Note that if an up-to-date derived file already exists in a repository, scons will not make a copy in the local directory tree. In order to guarantee that a local copy will be made, use the Local method.

Requires(target, prerequisite), env.Requires(target, prerequisite)
    Specifies an order-only relationship between target and prerequisite. The prerequisites will be (re)built, if necessary, before the target file(s), but the target file(s) do not actually depend on the prerequisites and will not be rebuilt simply because the prerequisite file(s) change. target and prerequisite may each be a string or Node, or a list of strings or Nodes. If there are multiple target values, the prerequisite(s) are added to each one. Returns a list of the affected target nodes.

    Example:

        env.Requires('foo', 'file-that-must-be-built-before-foo')

Return([vars..., stop=True])
    Return to the calling SConscript, optionally returning the values of variables named in vars. Multiple strings contaning variable names may be passed to Return. A string containing white space is split into individual variable names. Returns the value if one variable is specified, else returns a tuple of values. Returns an empty tuple if vars is omitted.

    By default Return stops processing the current SConscript and returns immediately. The optional stop keyword argument may be set to a false value to continue processing the rest of the SConscript file after the Return call (this was the default behavior prior to SCons 0.98.) However, the values returned are still the values of the variables in the named vars at the point Return was called.

    Examples:

        # Returns no values (evaluates False)
        Return()
        # Returns the value of the 'foo' Python variable.
        Return("foo")
        # Returns the values of the Python variables 'foo' and 'bar'.
        Return("foo", "bar")
        # Returns the values of Python variables 'val1' and 'val2'.
        Return('val1 val2')

Scanner(function, [name, argument, skeys, path_function, node_class, node_factory, scan_check, recursive]), env.Scanner(function, [name, argument, skeys, path_function, node_class, node_factory, scan_check, recursive])
    Creates a Scanner object for the specified function. See manpage section "Scanner Objects" for a complete explanation of the arguments and behavior.

SConscript(scriptnames, [exports, variant_dir, duplicate, must_exist]), env.SConscript(scriptnames, [exports, variant_dir, duplicate, must_exist]), SConscript(dirs=subdirs, [name=scriptname, exports, variant_dir, duplicate, must_exist]), env.SConscript(dirs=subdirs, [name=scriptname, exports, variant_dir, duplicate, must_exist])
    Executes subsidiary SConscript (build configuration) file(s). There are two ways to call the SConscript function.

    The first calling style is to supply one or more SConscript file names as the first positional argument, which can be a string or a list of strings. If there is a second positional argument, it is treated as if the exports keyword argument had been given (see below). Examples:

        SConscript('SConscript')  # run SConscript in the current directory
        SConscript('src/SConscript')  # run SConscript in the src directory
        SConscript(['src/SConscript', 'doc/SConscript'])
        SConscript(Split('src/SConscript doc/SConscript'))
        config = SConscript('MyConfig.py')

    The second calling style is to omit the positional argument naming the script and instead specify directory names using the dirs keyword argument. The value can be a string or list of strings. In this case, scons will execute a subsidiary configuration file named SConscript (by default) in each of the specified directories. You may specify a name other than SConscript by supplying an optional name=scriptname keyword argument. The first three examples below have the same effect as the first three examples above:

        SConscript(dirs='.')  # run SConscript in the current directory
        SConscript(dirs='src')  # run SConscript in the src directory
        SConscript(dirs=['src', 'doc'])
        SConscript(dirs=['sub1', 'sub2'], name='MySConscript')

    The optional exports keyword argument specifies variables to make available for use by the called SConscripts, which are evaluated in an isolated context and otherwise do not have access to local variables from the calling SConscript. The value may be a string or list of strings representing variable names, or a dictionary mapping local names to the names they can be imported by. For the first (scriptnames) calling style, a second positional argument will also be interpreted as exports; the second (directory) calling style accepts no positional arguments and must use the keyword form. These variables are locally exported only to the called SConscript file(s), and take precedence over any same-named variables in the global pool managed by the Export function. The subsidiary SConscript files must use the Import function to import the variables into their local scope. Examples:

        foo = SConscript('sub/SConscript', exports='env')
        SConscript('dir/SConscript', exports=['env', 'variable'])
        SConscript(dirs='subdir', exports='env variable')
        SConscript(dirs=['one', 'two', 'three'], exports='shared_info')

    If the optional variant_dir argument is present, it causes an effect equivalent to the VariantDir function, but in effect only within the scope of the SConscript call. The variant_dir argument is interpreted relative to the directory of the calling SConscript file. The source directory is the directory in which the called SConscript file resides and the SConscript file is evaluated as if it were in the variant_dir directory. Thus:

        SConscript('src/SConscript', variant_dir='build')

    is equivalent to:

        VariantDir('build', 'src')
        SConscript('build/SConscript')

    If the sources are in the same directory as the SConstruct,

        SConscript('SConscript', variant_dir='build')

    is equivalent to:

        VariantDir('build', '.')
        SConscript('build/SConscript')

    The optional duplicate argument is interpreted as for VariantDir. If the variant_dir argument is omitted, the duplicate argument is ignored. See the description of VariantDir for additional details and restrictions.

    If the optional must_exist is True (the default), an exception is raised if a requested SConscript file is not found. To allow missing scripts to be silently ignored (the default behavior prior to SCons version 3.1), pass must_exist=False in the SConscript call.

    Changed in 4.6.0: must_exist now defaults to True.

    Here are some composite examples:

        # collect the configuration information and use it to build src and doc
        shared_info = SConscript('MyConfig.py')
        SConscript('src/SConscript', exports='shared_info')
        SConscript('doc/SConscript', exports='shared_info')

        # build debugging and production versions.  SConscript
        # can use Dir('.').path to determine variant.
        SConscript('SConscript', variant_dir='debug', duplicate=0)
        SConscript('SConscript', variant_dir='prod', duplicate=0)

        # build debugging and production versions.  SConscript
        # is passed flags to use.
        opts = { 'CPPDEFINES' : ['DEBUG'], 'CCFLAGS' : '-pgdb' }
        SConscript('SConscript', variant_dir='debug', duplicate=0, exports=opts)
        opts = { 'CPPDEFINES' : ['NODEBUG'], 'CCFLAGS' : '-O' }
        SConscript('SConscript', variant_dir='prod', duplicate=0, exports=opts)

        # build common documentation and compile for different architectures
        SConscript('doc/SConscript', variant_dir='build/doc', duplicate=0)
        SConscript('src/SConscript', variant_dir='build/x86', duplicate=0)
        SConscript('src/SConscript', variant_dir='build/ppc', duplicate=0)

    SConscript returns the values of any variables named by the executed SConscript file(s) in arguments to the Return function. If a single SConscript call causes multiple scripts to be executed, the return value is a tuple containing the returns of each of the scripts. If an executed script does not explicitly call Return, it returns None.

SConscriptChdir(value)
    By default, scons changes its working directory to the directory in which each subsidiary SConscript file lives while reading and processing that script. This behavior may be disabled by specifying an argument which evaluates false, in which case scons will stay in the top-level directory while reading all SConscript files. (This may be necessary when building from repositories, when all the directories in which SConscript files may be found don't necessarily exist locally.) You may enable and disable this ability by calling SConscriptChdir multiple times.

    Example:

        SConscriptChdir(False)
        SConscript('foo/SConscript')	# will not chdir to foo
        SConscriptChdir(True)
        SConscript('bar/SConscript')	# will chdir to bar

SConsignFile([name, dbm_module]), env.SConsignFile([name, dbm_module])
    Specify where to store the SCons file signature database, and which database format to use. This may be useful to specify alternate database files and/or file locations for different types of builds.

    The optional name argument is the base name of the database file(s). If not an absolute path name, these are placed relative to the directory containing the top-level SConstruct file. The default is .sconsign. The actual database file(s) stored on disk may have an appropriate suffix appended by the chosen dbm_module

    The optional dbm_module argument specifies which Python database module to use for reading/writing the file. The module must be imported first; then the imported module name is passed as the argument. The default is a custom SCons.dblite module that uses pickled Python data structures, which works on all Python versions. See documentation of the Python dbm module for other available types.

    If called with no arguments, the database will default to .sconsign.dblite in the top directory of the project, which is also the default if if SConsignFile is not called.

    The setting is global, so the only difference between the global function and the environment method form is variable expansion on name. There should only be one active call to this function/method in a given build setup.

    If name is set to None, scons will store file signatures in a separate .sconsign file in each directory, not in a single combined database file. This is a backwards-compatibility meaure to support what was the default behavior prior to SCons 0.97 (i.e. before 2008). Use of this mode is discouraged and may be deprecated in a future SCons release.

    Examples:

        # Explicitly stores signatures in ".sconsign.dblite"
        # in the top-level SConstruct directory (the default behavior).
        SConsignFile()
        # Stores signatures in the file "etc/scons-signatures"
        # relative to the top-level SConstruct directory.
        # SCons will add a database suffix to this name.
        SConsignFile("etc/scons-signatures")
        # Stores signatures in the specified absolute file name.
        # SCons will add a database suffix to this name.
        SConsignFile("/home/me/SCons/signatures")
        # Stores signatures in a separate .sconsign file
        # in each directory.
        SConsignFile(None)
        # Stores signatures in a GNU dbm format .sconsign file
        import dbm.gnu
        SConsignFile(dbm_module=dbm.gnu)

env.SetDefault(key=val, [...])
    Sets construction variables to default values specified with the keyword arguments if (and only if) the variables are not already set. The following statements are equivalent:

        env.SetDefault(FOO='foo')
        if 'FOO' not in env:
            env['FOO'] = 'foo'

SetOption(name, value), env.SetOption(name, value)
    Sets scons option variable name to value. These options are all also settable via command-line options but the variable name may differ from the command-line option name - see the table for correspondences. A value set via command-line option will take precedence over one set with SetOption, which allows setting a project default in the scripts and temporarily overriding it via command line. SetOption calls can also be placed in the site_init.py file.

    See the documentation in the manpage for the corresponding command line option for information about each specific option. The value parameter is mandatory, for option values which are boolean in nature (that is, the command line option does not take an argument) use a value which evaluates to true (e.g. True, 1) or false (e.g. False, 0).

    Options which affect the reading and processing of SConscript files are not settable using SetOption since those files must be read in order to find the SetOption call in the first place.

    For project-specific options (sometimes called local options) added via an AddOption call, SetOption is available only after the AddOption call has completed successfully, and only if that call included the settable=True argument.

    The settable variables with their associated command-line options are:
    Settable name | Command-line options | Notes
    clean | -c, --clean, --remove |
    diskcheck | --diskcheck |
    duplicate | --duplicate |
    experimental | --experimental | since 4.2
    hash_chunksize | --hash-chunksize | Actually sets md5_chunksize. since 4.2
    hash_format | --hash-format | since 4.2
    help | -h, --help |
    implicit_cache | --implicit-cache |
    implicit_deps_changed | --implicit-deps-changed | Also sets implicit_cache. (settable since 4.2)
    implicit_deps_unchanged | --implicit-deps-unchanged | Also sets implicit_cache. (settable since 4.2)
    max_drift | --max-drift |
    md5_chunksize | --md5-chunksize |
    no_exec | -n, --no-exec, --just-print, --dry-run, --recon |
    no_progress | -Q | See [7]
    num_jobs | -j, --jobs |
    random | --random |
    silent | -s, --silent, --quiet |
    stack_size | --stack-size |
    warn | --warn |
    ---- [a] If no_progress is set via SetOption in an SConscript file (but not if set in a site_init.py file) there will still be an initial status message about reading SConscript files since SCons has to start reading them before it can see the SetOption.

    Example:

        SetOption('max_drift', 0)

SideEffect(side_effect, target), env.SideEffect(side_effect, target)
    Declares side_effect as a side effect of building target. Both side_effect and target can be a list, a file name, or a node. A side effect is a target file that is created or updated as a side effect of building other targets. For example, a Windows PDB file is created as a side effect of building the .obj files for a static library, and various log files are created updated as side effects of various TeX commands. If a target is a side effect of multiple build commands, scons will ensure that only one set of commands is executed at a time. Consequently, you only need to use this method for side-effect targets that are built as a result of multiple build commands.

    Because multiple build commands may update the same side effect file, by default the side_effect target is not automatically removed when the target is removed by the -c option. (Note, however, that the side_effect might be removed as part of cleaning the directory in which it lives.) If you want to make sure the side_effect is cleaned whenever a specific target is cleaned, you must specify this explicitly with the Clean or env.Clean function.

    This function returns the list of side effect Node objects that were successfully added. If the list of side effects contained any side effects that had already been added, they are not added and included in the returned list.

Split(arg), env.Split(arg)
    If arg is a string, splits on whitespace and returns a list of strings without whitespace. This mode is the most common case, and can be used to split a list of filenames (for example) rather than having to type them as a list of individually quoted words. If arg is a list or tuple returns the list or tuple unchanged. If arg is any other type of object, returns a list containing just the object. These non-string cases do not actually do any spliting, but allow an argument variable to be passed to Split without having to first check its type.

    Example:

        files = Split("f1.c f2.c f3.c")
        files = env.Split("f4.c f5.c f6.c")
        files = Split("""
            f7.c
            f8.c
            f9.c
        """)

env.subst(input, [raw, target, source, conv])
    Performs construction variable interpolation (substitution) on input, which can be a string or a sequence. Substitutable elements take the form ${expression}, although if there is no ambiguity in recognizing the element, the braces can be omitted. A literal $ can be entered by using $$.

    By default, leading or trailing white space will be removed from the result, and all sequences of white space will be compressed to a single space character. Additionally, any $( and $) character sequences will be stripped from the returned string, The optional raw argument may be set to 1 if you want to preserve white space and $(-$) sequences. The raw argument may be set to 2 if you want to additionally discard all characters between any $( and $) pairs (as is done for signature calculation).

    If input is a sequence (list or tuple), the individual elements of the sequence will be expanded, and the results will be returned as a list.

    The optional target and source keyword arguments must be set to lists of target and source nodes, respectively, if you want the $TARGET, $TARGETS, $SOURCE and $SOURCES to be available for expansion. This is usually necessary if you are calling env.subst from within a Python function used as an SCons action.

    Returned string values or sequence elements are converted to their string representation by default. The optional conv argument may specify a conversion function that will be used in place of the default. For example, if you want Python objects (including SCons Nodes) to be returned as Python objects, you can use a Python lambda expression to pass in an unnamed function that simply returns its unconverted argument.

    Example:

        print(env.subst("The C compiler is: $CC"))
        def compile(target, source, env):
            sourceDir = env.subst(
                "${SOURCE.srcdir}",
                target=target,
                source=source
            )
        source_nodes = env.subst('$EXPAND_TO_NODELIST', conv=lambda x: x)

Tag(node, tags)
    Annotates file or directory Nodes with information about how the Package Builder should package those files or directories. All Node-level tags are optional.

    Examples:

        # makes sure the built library will be installed with 644 file access mode
        Tag(Library('lib.c'), UNIX_ATTR="0o644")
        # marks file2.txt to be a documentation file
        Tag('file2.txt', DOC)

Tool(name, [toolpath, key=value, ...]), env.Tool(name, [toolpath, key=value, ...])
    Locates the tool specification module name and returns a callable tool object for that tool. When the environment method (env.Tool) form is used, the tool object is automatically called before the method returns to update env, and name is appended to the $TOOLS construction variable in that environment. When the global function Tool form is used, the tool object is constructed but not called, as it lacks the context of an environment to update, and the returned object needs to be used to arrange for the call.

    The tool module is searched for in the tool search paths (see the Tools section in the manual page for details) and in any paths specified by the optional toolpath parameter, which must be a list of strings. If toolpath is omitted, the toolpath supplied when the environment was created, if any, is used.

    Any remaining keyword arguments are saved in the tool object, and will be passed to the tool module's generate function when the tool object is actually called. The generate function can update the construction environment with construction variables and arrange any other initialization needed to use the mechanisms that tool describes, and can use these extra arguments to help guide its actions.

    Changed in version 4.2: env.Tool now returns the tool object, previously it did not return (i.e. returned None).

    Examples:

        env.Tool('gcc')
        env.Tool('opengl', toolpath=['build/tools'])

    The returned tool object can be passed to an Environment or Clone call as part of the tools keyword argument, in which case the tool is applied to the environment being constructed, or it can be called directly, in which case a construction environment to update must be passed as the argument. Either approach will also update the $TOOLS construction variable.

    Examples:

        env = Environment(tools=[Tool('msvc')])
        env = Environment()
        msvctool = Tool('msvc')
        msvctool(env)  # adds 'msvc' to the TOOLS variable
        gltool = Tool('opengl', toolpath = ['tools'])
        gltool(env)  # adds 'opengl' to the TOOLS variable

ValidateOptions([throw_exception=False])
    Check that all the options specified on the command line are either SCons built-in options or defined via calls to AddOption. SCons will eventually fail on unknown options anyway, but calling this function allows the build to "fail fast" before executing expensive logic later in the build.

    This function should only be called after the last AddOption call in your SConscript logic. Be aware that some tools call AddOption, if you are getting error messages for arguments that they add, you will need to ensure that those tools are loaded before calling ValidateOptions.

    If there are any unknown command line options, ValidateOptions prints an error message and exits with an error exit status. If the optional throw_exception argument is True (default is False), a SConsBadOptionError is raised, giving an opportunity for the SConscript logic to catch that exception and handle invalid options appropriately. Note that this exception name needs to be imported (see the example below).

    A common build problem is typos (or thinkos) - a user enters an option that is just a little off the expected value, or perhaps a different word with a similar meaning. It may be useful to abort the build before going too far down the wrong path. For example:

        $ scons --compilers=mingw  # the correct flag is --compiler

    Here SCons could go off and run a bunch of configure steps with the default value of --compiler, since the incorrect command line did not actually supply a value to it, costing developer time to track down why the configure logic made the "wrong" choices. This example shows catching this:

        from SCons.Script.SConsOptions import SConsBadOptionError
        AddOption(
            '--compiler',
            dest='compiler',
            action='store',
            default='gcc',
            type='string',
        )
        # ... other SConscript logic ...
        try:
            ValidateOptions(throw_exception=True)
        except SConsBadOptionError as e:
            print(f"ValidateOptions detects a fail: ", e.opt_str)
            Exit(3)

    New in version 4.5.0

Value(value, [built_value], [name]), env.Value(value, [built_value], [name])
    Returns a Node object representing the specified Python value. Value Nodes can be used as dependencies of targets. If the string representation of the Value Node changes between SCons runs, it is considered out of date and any targets depending it will be rebuilt. Since Value Nodes have no filesystem representation, timestamps are not used; the timestamp deciders perform the same content-based up to date check.

    The optional built_value argument can be specified when the Value Node is created to indicate the Node should already be considered "built."

    The optional name parameter can be provided as an alternative name for the resulting Value node; this is advised if the value parameter cannot be converted to a string.

    Value Nodes have a write method that can be used to "build" a Value Node by setting a new value. The corresponding read method returns the built value of the Node.

    Changed in version 4.0: the name parameter was added.

    Examples:

        env = Environment()
        def create(target, source, env):
            """Action function to create a file from a Value.
            Writes 'prefix=$SOURCE' into the file name given as $TARGET.
            """
            with open(str(target[0]), 'wb') as f:
                f.write(b'prefix=' + source[0].get_contents() + b'\n')
        # Fetch the prefix= argument, if any, from the command line.
        # Use /usr/local as the default.
        prefix = ARGUMENTS.get('prefix', '/usr/local')
        # Attach builder named Config to the construction environment
        # using the 'create' action function above.
        env['BUILDERS']['Config'] = Builder(action=create)
        env.Config(target='package-config', source=Value(prefix))
        def build_value(target, source, env):
            """Action function to "build" a Value.
            Writes contents of $SOURCE into $TARGET, thus updating if it existed.
            """
            target[0].write(source[0].get_contents())
        output = env.Value('before')
        input = env.Value('after')
        # Attach a builder named UpdateValue to the construction environment
        # using the 'build_value' action function above.
        env['BUILDERS']['UpdateValue'] = Builder(action=build_value)
        env.UpdateValue(target=Value(output), source=Value(input))

VariantDir(variant_dir, src_dir, [duplicate]), env.VariantDir(variant_dir, src_dir, [duplicate])
    Sets up a mapping to define a variant build directory in variant_dir. src_dir must not be underneath variant_dir. A VariantDir mapping is global, even if called using the env.VariantDir form. VariantDir can be called multiple times with the same src_dir to set up multiple variant builds with different options.

    Note if variant_dir is not under the project top directory, target selection rules will not pick targets in the variant directory unless they are explicitly specified.

    When files in variant_dir are referenced, SCons backfills as needed with files from src_dir to create a complete build directory. By default, SCons physically duplicates the source files, SConscript files, and directory structure as needed into the variant directory. Thus, a build performed in the variant directory is guaranteed to be identical to a build performed in the source directory even if intermediate source files are generated during the build, or if preprocessors or other scanners search for included files using paths relative to the source file, or if individual compilers or other invoked tools are hard-coded to put derived files in the same directory as source files. Only the files SCons calculates are needed for the build are duplicated into variant_dir. If possible on the platform, the duplication is performed by linking rather than copying. This behavior is affected by the --duplicate command-line option.

    Duplicating the source files may be disabled by setting the duplicate argument to False. This will cause SCons to invoke Builders using the path names of source files in src_dir and the path names of derived files within variant_dir. This is more efficient than duplicating, and is safe for most builds; revert to duplicate=True if it causes problems.

    VariantDir works most naturally when used with a subsidiary SConscript file. The subsidiary SConscript file must be called as if it were in variant_dir, regardless of the value of duplicate. When calling an SConscript file, you can use the exports keyword argument to pass parameters (individually or as an appropriately set up environment) so the SConscript can pick up the right settings for that variant build. The SConscript must Import these to use them. Example:

        env1 = Environment(...settings for variant1...)
        env2 = Environment(...settings for variant2...)
        # run src/SConscript in two variant directories
        VariantDir('build/variant1', 'src')
        SConscript('build/variant1/SConscript', exports={"env": env1})
        VariantDir('build/variant2', 'src')
        SConscript('build/variant2/SConscript', exports={"env": env2})

    See also the SConscript function for another way to specify a variant directory in conjunction with calling a subsidiary SConscript file.

    More examples:

        # use names in the build directory, not the source directory
        VariantDir('build', 'src', duplicate=0)
        Program('build/prog', 'build/source.c')
        # this builds both the source and docs in a separate subtree
        VariantDir('build', '.', duplicate=0)
        SConscript(dirs=['build/src','build/doc'])
        # same as previous example, but only uses SConscript
        SConscript(dirs='src', variant_dir='build/src', duplicate=0)
        SConscript(dirs='doc', variant_dir='build/doc', duplicate=0)

WhereIs(program, [path, pathext, reject]), env.WhereIs(program, [path, pathext, reject])
    Searches for the specified executable program, returning the full path to the program or None.

    When called as a construction environment method, searches the paths in the path keyword argument, or if None (the default) the paths listed in the construction environment (env['ENV']['PATH']). The external environment's path list (os.environ['PATH']) is used as a fallback if the key env['ENV']['PATH'] does not exist.

    On Windows systems, searches for executable programs with any of the file extensions listed in the pathext keyword argument, or if None (the default) the pathname extensions listed in the construction environment (env['ENV']['PATHEXT']). The external environment's pathname extensions list (os.environ['PATHEXT']) is used as a fallback if the key env['ENV']['PATHEXT'] does not exist.

    When called as a global function, uses the external environment's path os.environ['PATH'] and path extensions os.environ['PATHEXT'], respectively, if path and pathext are None.

    Will not select any path name or names in the optional reject list.

  SConscript Variables

In addition to the global functions and methods, scons supports a number of variables that can be used for run-time queries in SConscript files to affect how you want the build to be performed.

ARGLIST
    A list of the variable=value build variable arguments specified on the command line. Each element in the list is a tuple consisting of the variable and its value. The separate variable and value elements of the tuple can be accessed by subscripting for elements [0] and [1] of the tuple, or, more readably, by using tuple unpacking. Examples:

        print("first variable, value =", ARGLIST[0][0], ARGLIST[0][1])
        print("second variable, value =", ARGLIST[1][0], ARGLIST[1][1])
        var, value = ARGLIST[2]
        print("third variable, value =", var, value)
        for var, value in ARGLIST:
            # process variable and value

    The values obtained from ARGLIST (or from ARGUMENTS) are always strings since they originate from outside the SCons process. As "untrusted data", they should be validated before usage, and may need conversion to an appropriate type.

ARGUMENTS
    A dictionary of all the variable=value build variable arguments specified on the command line. The dictionary is in command-line order, so if a given variable has more than one value assigned to it on the command line, the last (right-most) value is the one saved in the ARGUMENTS dictionary.

    Example:

        if ARGUMENTS.get("debug", ""):
            env = Environment(CCFLAGS="-g")
        else:
            env = Environment()

    See also ARGLIST.

BUILD_TARGETS
    A list of the targets which scons has been asked to build. The contents will be either those targets listed on the command line, or, if none, those targets set via calls to the Default function. It does not contain any dependent targets that scons selects for building as a result of making the sure the specified targets are up to date, if those targets did not appear on the command line. The list is empty if neither command line targets or Default calls are present.

    The elements of this list may be strings or nodes, so you should run the list through the Python str function to make sure any Node path names are converted to strings.

    Because this list may be taken from the list of targets specified using the Default function, the contents of the list may change on each successive call to Default. See DEFAULT_TARGETS for additional information.

    Example:

        if 'foo' in BUILD_TARGETS:
            print("Don't forget to test the `foo' program!")
        if 'special/program' in BUILD_TARGETS:
            SConscript('special')

COMMAND_LINE_TARGETS
    A list of the targets explicitly specified on the command line. If there are command line targets, this list has the same contents as BUILD_TARGETS. If there are no targets specified on the command line, the list is empty. The elements of this list are strings. This can be used, for example, to take specific actions only when a certain targets is explicitly requested for building.

    Example:

        if 'foo' in COMMAND_LINE_TARGETS:
            print("Don't forget to test the `foo' program!")
        if 'special/program' in COMMAND_LINE_TARGETS:
            SConscript('special')

DEFAULT_TARGETS
    A list of the target nodes that have been specified using the Default function. If there are no command line targets, this list will have the same contents as BUILD_TARGETS. Since the elements of the list are nodes, you need to call the Python str function on them to get the path name for each Node.

    Example:

        print(str(DEFAULT_TARGETS[0]))
        if 'foo' in [str(t) for t in DEFAULT_TARGETS]:
            print("Don't forget to test the `foo' program!")

    The contents of the DEFAULT_TARGETS list change on on each successive call to the Default function:

        print([str(t) for t in DEFAULT_TARGETS])   # originally []
        Default('foo')
        print([str(t) for t in DEFAULT_TARGETS])   # now a node ['foo']
        Default('bar')
        print([str(t) for t in DEFAULT_TARGETS])   # now a node ['foo', 'bar']
        Default(None)
        print([str(t) for t in DEFAULT_TARGETS])   # back to []

    Consequently, be sure to use DEFAULT_TARGETS only after you've made all of your Default() calls, or else simply be careful of the order of these statements in your SConscript files so that you don't look for a specific default target before it's actually been added to the list.

These variables may be accessed from custom Python modules that you import into an SConscript file by adding the following to the Python module:

    from SCons.Script import *

  Construction Variables

Construction Variables are key-value pairs used to store information in a construction environment that is needed needed for builds using that environment. Construction variable naming must follow the same rules as Python identifier naming: the initial character must be an underscore or letter, followed by any number of underscores, letters, or digits. The convention is to use uppercase for all letters for easier visual identification.

Construction variables are used to hold many different types of information. For example, the $CPPDEFINES variable is how to tell a C/C++ compiler about preprocessor macros you need for your build. The tool discovery that SCons performs will cause the $CXX variable to hold the name of the C++ compiler, if one was detected on the system, but you can give it a different value to force a compiler command of a different name to be used. Some variables contain lists of filename suffixes that are recognized by a particular compiler chain. $BUILDERS contains a mapping of configured Builder names (e.g. Textfile) to the actual Builder instance to call when that Builder is used. Construction variables may include references to other construction variables: the same tool which set up the C/C++ compiler will also set up an "action string", describing how to invoke that compiler, in $CXXCOM, which contains other construction variables using $VARIABLE syntax. These references will be expanded and replaced on use (see Variable Substitution).

Construction variables are referenced as if they were keys and values in a Python dictionary:

    env["CC"] = "cc"
    flags = env.get("CPPDEFINES", [])

Construction variables can also be retrieved and set by using the Dictionary method of the construction environment to create an actual dictionary:

    cvars = env.Dictionary()
    cvars["CC"] = "cc"

in the previous example, since cvars is an external copy, the value of $CC in the construction environment itself is not changed by the assignment.

Construction variables can set by passing them as keyword arguments when creating a new construction environment:

    env = Environment(CC="cc")

or when copying a construction environment using the Clone method:

    env2 = env.Clone(CC="cl.exe")

Construction variables can also be supplied as keyword arguments to a builder, in which case those settings affect only the work done by that builder call, and not the construction environment as a whole. This concept is called an override:

    env.Program('hello', 'hello.c', LIBS=['gl', 'glut'])

Many useful construction variables are automatically defined by SCons, tuned to the specific platform in use, and you can modify these or define any additional construction variables for use in your own Builders, Scanners and other tools. Take care not to overwrite ones which SCons is using. The following is a list of predefined construction variables. Pay attention to whether the values are ones you may be expected to set vs. ones that are set to expected values by internal tools and other initializations and probably should not be modified.

Note the actual list available at execution time will never include all of these, as the ones detected as not being applicable (wrong platform, necessary external command or files not installed, etc.) will not be set up. Correct build setups should be resilient to the possible absence of certain construction variables before using them, for example by using a Python dictionary get method to retrieve the value and taking alternative action if the return indicates the variable is unset. The env.Dump method can be called to examine the construction variables set in a particular environment.

__LDMODULEVERSIONFLAGS
    This construction variable automatically introduces $_LDMODULEVERSIONFLAGS if $LDMODULEVERSION is set. Othervise it evaluates to an empty string.

__SHLIBVERSIONFLAGS
    This construction variable automatically introduces $_SHLIBVERSIONFLAGS if $SHLIBVERSION is set. Othervise it evaluates to an empty string.

APPLELINK_COMPATIBILITY_VERSION
    On Mac OS X this is used to set the linker flag: -compatibility_version

    The value is specified as X[.Y[.Z]] where X is between 1 and 65535, Y can be omitted or between 1 and 255, Z can be omitted or between 1 and 255. This value will be derived from $SHLIBVERSION if not specified. The lowest digit will be dropped and replaced by a 0.

    If the $APPLELINK_NO_COMPATIBILITY_VERSION is set then no -compatibility_version will be output.

    See MacOS's ld manpage for more details

_APPLELINK_COMPATIBILITY_VERSION
    A macro (by default a generator function) used to create the linker flags to specify apple's linker's -compatibility_version flag. The default generator uses $APPLELINK_COMPATIBILITY_VERSION and $APPLELINK_NO_COMPATIBILITY_VERSION and $SHLIBVERSION to determine the correct flag.

APPLELINK_CURRENT_VERSION
    On Mac OS X this is used to set the linker flag: -current_version

    The value is specified as X[.Y[.Z]] where X is between 1 and 65535, Y can be omitted or between 1 and 255, Z can be omitted or between 1 and 255. This value will be set to $SHLIBVERSION if not specified.

    If the $APPLELINK_NO_CURRENT_VERSION is set then no -current_version will be output.

    See MacOS's ld manpage for more details

_APPLELINK_CURRENT_VERSION
    A macro (by default a generator function) used to create the linker flags to specify apple's linker's -current_version flag. The default generator uses $APPLELINK_CURRENT_VERSION and $APPLELINK_NO_CURRENT_VERSION and $SHLIBVERSION to determine the correct flag.

APPLELINK_NO_COMPATIBILITY_VERSION
    Set this to any True (1|True|non-empty string) value to disable adding -compatibility_version flag when generating versioned shared libraries.

    This overrides $APPLELINK_COMPATIBILITY_VERSION.

APPLELINK_NO_CURRENT_VERSION
    Set this to any True (1|True|non-empty string) value to disable adding -current_version flag when generating versioned shared libraries.

    This overrides $APPLELINK_CURRENT_VERSION.

AR
    The static library archiver.

ARCHITECTURE
    Specifies the system architecture for which the package is being built. The default is the system architecture of the machine on which SCons is running. This is used to fill in the Architecture: field in an Ipkg control file, and the BuildArch: field in the RPM .spec file, as well as forming part of the name of a generated RPM package file.

    See the Package builder.

ARCOM
    The command line used to generate a static library from object files.

ARCOMSTR
    The string displayed when a static library is generated from object files. If this is not set, then $ARCOM (the command line) is displayed.

        env = Environment(ARCOMSTR = "Archiving $TARGET")

ARFLAGS
    General options passed to the static library archiver.

AS
    The assembler.

ASCOM
    The command line used to generate an object file from an assembly-language source file.

ASCOMSTR
    The string displayed when an object file is generated from an assembly-language source file. If this is not set, then $ASCOM (the command line) is displayed.

        env = Environment(ASCOMSTR = "Assembling $TARGET")

ASFLAGS
    General options passed to the assembler.

ASPPCOM
    The command line used to assemble an assembly-language source file into an object file after first running the file through the C preprocessor. Any options specified in the $ASFLAGS and $CPPFLAGS construction variables are included on this command line.

ASPPCOMSTR
    The string displayed when an object file is generated from an assembly-language source file after first running the file through the C preprocessor. If this is not set, then $ASPPCOM (the command line) is displayed.

        env = Environment(ASPPCOMSTR = "Assembling $TARGET")

ASPPFLAGS
    General options when an assembling an assembly-language source file into an object file after first running the file through the C preprocessor. The default is to use the value of $ASFLAGS.

BIBTEX
    The bibliography generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

BIBTEXCOM
    The command line used to call the bibliography generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

BIBTEXCOMSTR
    The string displayed when generating a bibliography for TeX or LaTeX. If this is not set, then $BIBTEXCOM (the command line) is displayed.

        env = Environment(BIBTEXCOMSTR = "Generating bibliography $TARGET")

BIBTEXFLAGS
    General options passed to the bibliography generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

BUILDERS
    A dictionary mapping the names of the builders available through the construction environment to underlying Builder objects. Custom builders need to be added to this to make them available.

    A platform-dependent default list of builders such as Program, Library etc. is used to populate this construction variable when the construction environment is initialized via the presence/absence of the tools those builders depend on. $BUILDERS can be examined to learn which builders will actually be available at run-time.

    Note that if you initialize this construction variable through assignment when the construction environment is created, that value for $BUILDERS will override any defaults:

        bld = Builder(action='foobuild < $SOURCE > $TARGET')
        env = Environment(BUILDERS={'NewBuilder': bld})

    To instead use a new Builder object in addition to the default Builders, add your new Builder object like this:

        env = Environment()
        env.Append(BUILDERS={'NewBuilder': bld})

    or this:

        env = Environment()
        env['BUILDERS']['NewBuilder'] = bld

CACHEDIR_CLASS
    The class type that SCons should use when instantiating a new CacheDir in this construction environment. Must be a subclass of the SCons.CacheDir.CacheDir class.

CC
    The C compiler.

CCCOM
    The command line used to compile a C source file to a (static) object file. Any options specified in the $CFLAGS, $CCFLAGS and $CPPFLAGS construction variables are included on this command line. See also $SHCCCOM for compiling to shared objects.

CCCOMSTR
    If set, the string displayed when a C source file is compiled to a (static) object file. If not set, then $CCCOM (the command line) is displayed. See also $SHCCCOMSTR for compiling to shared objects.

        env = Environment(CCCOMSTR = "Compiling static object $TARGET")

CCDEPFLAGS
    Options to pass to C or C++ compiler to generate list of dependency files.

    This is set only by compilers which support this functionality. (gcc, clang, and msvc currently)

CCFLAGS
    General options that are passed to the C and C++ compilers. See also $SHCCFLAGS for compiling to shared objects.

CCPCHFLAGS
    Options added to the compiler command line to support building with precompiled headers. The default value expands expands to the appropriate Microsoft Visual C++ command-line options when the $PCH construction variable is set.

CCPDBFLAGS
    Options added to the compiler command line to support storing debugging information in a Microsoft Visual C++ PDB file. The default value expands expands to appropriate Microsoft Visual C++ command-line options when the $PDB construction variable is set.

    The Microsoft Visual C++ compiler option that SCons uses by default to generate PDB information is /Z7. This works correctly with parallel (-j) builds because it embeds the debug information in the intermediate object files, as opposed to sharing a single PDB file between multiple object files. This is also the only way to get debug information embedded into a static library. Using the /Zi instead may yield improved link-time performance, although parallel builds will no longer work.

    You can generate PDB files with the /Zi switch by overriding the default $CCPDBFLAGS variable as follows:

        env['CCPDBFLAGS'] = ['${(PDB and "/Zi /Fd%s" % File(PDB)) or ""}']

    An alternative would be to use the /Zi to put the debugging information in a separate .pdb file for each object file by overriding the $CCPDBFLAGS variable as follows:

        env['CCPDBFLAGS'] = '/Zi /Fd${TARGET}.pdb'

CCVERSION
    The version number of the C compiler. This may or may not be set, depending on the specific C compiler being used.

CFILESUFFIX
    The suffix for C source files. This is used by the internal CFile builder when generating C files from Lex (.l) or YACC (.y) input files. The default suffix, of course, is .c (lower case). On case-insensitive systems (like Windows), SCons also treats .C (upper case) files as C files.

CFLAGS
    General options that are passed to the C compiler (C only; not C++). See also $SHCFLAGS for compiling to shared objects.

CHANGE_SPECFILE
    A hook for modifying the file that controls the packaging build (the .spec for RPM, the control for Ipkg, the .wxs for MSI). If set, the function will be called after the SCons template for the file has been written.

    See the Package builder.

CHANGED_SOURCES
    A reserved variable name that may not be set or used in a construction environment. (See the manpage section "Variable Substitution" for more information).

CHANGED_TARGETS
    A reserved variable name that may not be set or used in a construction environment. (See the manpage section "Variable Substitution" for more information).

CHANGELOG
    The name of a file containing the change log text to be included in the package. This is included as the %changelog section of the RPM .spec file.

    See the Package builder.

COMPILATIONDB_COMSTR
    The string displayed when the CompilationDatabase builder's action is run.

COMPILATIONDB_PATH_FILTER
    A string which instructs CompilationDatabase to only include entries where the output member matches the pattern in the filter string using fnmatch, which uses glob style wildcards.

    The default value is an empty string '', which disables filtering.

COMPILATIONDB_USE_ABSPATH
    A boolean flag to instruct CompilationDatabase whether to write the file and output members in the compilation database using absolute or relative paths.

    The default value is False (use relative paths)

_concat
    A function used to produce variables like $_CPPINCFLAGS. It takes four mandatory arguments, and up to 4 additional optional arguments: 1) a prefix to concatenate onto each element, 2) a list of elements, 3) a suffix to concatenate onto each element, 4) an environment for variable interpolation, 5) an optional function that will be called to transform the list before concatenation, 6) an optionally specified target (Can use TARGET), 7) an optionally specified source (Can use SOURCE), 8) optional affect_signature flag which will wrap non-empty returned value with $( and $) to indicate the contents should not affect the signature of the generated command line.

                env['_CPPINCFLAGS'] = '${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs, TARGET, SOURCE, affect_signature=False)}'

CONFIGUREDIR
    The name of the directory in which Configure context test files are written. The default is .sconf_temp in the top-level directory containing the SConstruct file.

    If variant directories are in use, and the configure check results should not be shared between variants, you can set $CONFIGUREDIR and $CONFIGURELOG so they are unique per variant directory.

CONFIGURELOG
    The name of the Configure context log file. The default is config.log in the top-level directory containing the SConstruct file.

    If variant directories are in use, and the configure check results should not be shared between variants, you can set $CONFIGUREDIR and $CONFIGURELOG so they are unique per variant directory.

_CPPDEFFLAGS
    An automatically-generated construction variable containing the C preprocessor command-line options to define values. The value of $_CPPDEFFLAGS is created by respectively prepending and appending $CPPDEFPREFIX and $CPPDEFSUFFIX to each definition in $CPPDEFINES.

CPPDEFINES
    A platform independent specification of C preprocessor macro definitions. The definitions are added to command lines through the automatically-generated $_CPPDEFFLAGS construction variable, which is constructed according to the contents of $CPPDEFINES:

        • If $CPPDEFINES is a string, the values of the $CPPDEFPREFIX and $CPPDEFSUFFIX construction variables are respectively prepended and appended to each definition in $CPPDEFINES, split on whitespace.

            # Adds -Dxyz to POSIX compiler command lines,
            # and /Dxyz to Microsoft Visual C++ command lines.
            env = Environment(CPPDEFINES='xyz')

        • If $CPPDEFINES is a list, the values of the $CPPDEFPREFIX and $CPPDEFSUFFIX construction variables are respectively prepended and appended to each element in the list. If any element is a tuple (or list) then the first item of the tuple is the macro name and the second is the macro definition. If the definition is not omitted or None, the name and definition are combined into a single name=definition item before the preending/appending.

            # Adds -DB=2 -DA to POSIX compiler command lines,
            # and /DB=2 /DA to Microsoft Visual C++ command lines.
            env = Environment(CPPDEFINES=[('B', 2), 'A'])

        • If $CPPDEFINES is a dictionary, the values of the $CPPDEFPREFIX and $CPPDEFSUFFIX construction variables are respectively prepended and appended to each key from the dictionary. If the value for a key is not None, then the key (macro name) and the value (macros definition) are combined into a single name=definition item before the prepending/appending.

            # Adds -DA -DB=2 to POSIX compiler command lines,
            # or /DA /DB=2 to Microsoft Visual C++ command lines.
            env = Environment(CPPDEFINES={'B':2, 'A':None})

    Depending on how contents are added to $CPPDEFINES, it may be transformed into a compound type, for example a list containing strings, tuples and/or dictionaries. SCons can correctly expand such a compound type.

    Note that SCons may call the compiler via a shell. If a macro definition contains characters such as spaces that have meaning to the shell, or is intended to be a string value, you may need to use the shell's quoting syntax to avoid interpretation by the shell before the preprocessor sees it. Function-like macros are not supported via this mechanism (and some compilers do not even implement that functionality via the command lines). When quoting, note that one set of quote characters are used to define a Python string, then quotes embedded inside that would be consumed by the shell unless escaped. These examples may help illustrate:

        env = Environment(CPPDEFINES=['USE_ALT_HEADER=\\"foo_alt.h\\"'])
        env = Environment(CPPDEFINES=[('USE_ALT_HEADER', '\\"foo_alt.h\\"')])

    :Changed in version 4.5: SCons no longer sorts $CPPDEFINES values entered in dictionary form. Python now preserves dictionary keys in the order they are entered, so it is no longer necessary to sort them to ensure a stable command line.

CPPDEFPREFIX
    The prefix used to specify preprocessor macro definitions on the C compiler command line. This will be prepended to each definition in the $CPPDEFINES construction variable when the $_CPPDEFFLAGS variable is automatically generated.

CPPDEFSUFFIX
    The suffix used to specify preprocessor macro definitions on the C compiler command line. This will be appended to each definition in the $CPPDEFINES construction variable when the $_CPPDEFFLAGS variable is automatically generated.

CPPFLAGS
    User-specified C preprocessor options. These will be included in any command that uses the C preprocessor, including not just compilation of C and C++ source files via the $CCCOM, $SHCCCOM, $CXXCOM and $SHCXXCOM command lines, but also the $FORTRANPPCOM, $SHFORTRANPPCOM, $F77PPCOM and $SHF77PPCOM command lines used to compile a Fortran source file, and the $ASPPCOM command line used to assemble an assembly language source file, after first running each file through the C preprocessor. Note that this variable does not contain -I (or similar) include search path options that scons generates automatically from $CPPPATH. See $_CPPINCFLAGS, below, for the variable that expands to those options.

_CPPINCFLAGS
    An automatically-generated construction variable containing the C preprocessor command-line options for specifying directories to be searched for include files. The value of $_CPPINCFLAGS is created by respectively prepending and appending $INCPREFIX and $INCSUFFIX to each directory in $CPPPATH.

CPPPATH
    The list of directories that the C preprocessor will search for include directories. The C/C++ implicit dependency scanner will search these directories for include files. In general it's not advised to put include directory directives directly into $CCFLAGS or $CXXFLAGS as the result will be non-portable and the directories will not be searched by the dependency scanner. $CPPPATH should be a list of path strings, or a single string, not a pathname list joined by Python's os.pathsep.

    Note: directory names in $CPPPATH will be looked-up relative to the directory of the SConscript file when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use the # prefix:

        env = Environment(CPPPATH='#/include')

    The directory look-up can also be forced using the Dir function:

        include = Dir('include')
        env = Environment(CPPPATH=include)

    The directory list will be added to command lines through the automatically-generated $_CPPINCFLAGS construction variable, which is constructed by respectively prepending and appending the values of the $INCPREFIX and $INCSUFFIX construction variables to each directory in $CPPPATH. Any command lines you define that need the $CPPPATH directory list should include $_CPPINCFLAGS:

        env = Environment(CCCOM="my_compiler $_CPPINCFLAGS -c -o $TARGET $SOURCE")

CPPSUFFIXES
    The list of suffixes of files that will be scanned for C preprocessor implicit dependencies (#include lines). The default list is:

        [".c", ".C", ".cxx", ".cpp", ".c++", ".cc",
         ".h", ".H", ".hxx", ".hpp", ".hh",
         ".F", ".fpp", ".FPP",
         ".m", ".mm",
         ".S", ".spp", ".SPP"]

CXX
    The C++ compiler. See also $SHCXX for compiling to shared objects..

CXXCOM
    The command line used to compile a C++ source file to an object file. Any options specified in the $CXXFLAGS and $CPPFLAGS construction variables are included on this command line. See also $SHCXXCOM for compiling to shared objects..

CXXCOMSTR
    If set, the string displayed when a C++ source file is compiled to a (static) object file. If not set, then $CXXCOM (the command line) is displayed. See also $SHCXXCOMSTR for compiling to shared objects..

        env = Environment(CXXCOMSTR = "Compiling static object $TARGET")

CXXFILESUFFIX
    The suffix for C++ source files. This is used by the internal CXXFile builder when generating C++ files from Lex (.ll) or YACC (.yy) input files. The default suffix is .cc. SCons also treats files with the suffixes .cpp, .cxx, .c++, and .C++ as C++ files, and files with .mm suffixes as Objective C++ files. On case-sensitive systems (Linux, UNIX, and other POSIX-alikes), SCons also treats .C (upper case) files as C++ files.

CXXFLAGS
    General options that are passed to the C++ compiler. By default, this includes the value of $CCFLAGS, so that setting $CCFLAGS affects both C and C++ compilation. If you want to add C++-specific flags, you must set or override the value of $CXXFLAGS. See also $SHCXXFLAGS for compiling to shared objects..

CXXVERSION
    The version number of the C++ compiler. This may or may not be set, depending on the specific C++ compiler being used.

DC
    The D compiler to use. See also $SHDC for compiling to shared objects.

DCOM
    The command line used to compile a D file to an object file. Any options specified in the $DFLAGS construction variable is included on this command line. See also $SHDCOM for compiling to shared objects.

DCOMSTR
    If set, the string displayed when a D source file is compiled to a (static) object file. If not set, then $DCOM (the command line) is displayed. See also $SHDCOMSTR for compiling to shared objects.

DDEBUG
    List of debug tags to enable when compiling.

DDEBUGPREFIX
    DDEBUGPREFIX.

DDEBUGSUFFIX
    DDEBUGSUFFIX.

DESCRIPTION
    A long description of the project being packaged. This is included in the relevant section of the file that controls the packaging build.

    See the Package builder.

DESCRIPTION_lang
    A language-specific long description for the specified lang. This is used to populate a %description -l section of an RPM .spec file.

    See the Package builder.

DFILESUFFIX
    DFILESUFFIX.

DFLAGPREFIX
    DFLAGPREFIX.

DFLAGS
    General options that are passed to the D compiler.

DFLAGSUFFIX
    DFLAGSUFFIX.

DI_FILE_DIR
    Path where .di files will be generated

DI_FILE_DIR_PREFIX
    Prefix to send the di path argument to compiler

DI_FILE_DIR_SUFFFIX
    Suffix to send the di path argument to compiler

DI_FILE_SUFFIX
    Suffix of d include files default is .di

DINCPREFIX
    DINCPREFIX.

DINCSUFFIX
    DLIBFLAGSUFFIX.

Dir
    A function that converts a string into a Dir instance relative to the target being built.

Dirs
    A function that converts a list of strings into a list of Dir instances relative to the target being built.

DLIB
    Name of the lib tool to use for D codes.

DLIBCOM
    The command line to use when creating libraries.

DLIBDIRPREFIX
    DLIBLINKPREFIX.

DLIBDIRSUFFIX
    DLIBLINKSUFFIX.

DLIBFLAGPREFIX
    DLIBFLAGPREFIX.

DLIBFLAGSUFFIX
    DLIBFLAGSUFFIX.

DLIBLINKPREFIX
    DLIBLINKPREFIX.

DLIBLINKSUFFIX
    DLIBLINKSUFFIX.

DLINK
    Name of the linker to use for linking systems including D sources. See also $SHDLINK for linking shared objects.

DLINKCOM
    The command line to use when linking systems including D sources. See also $SHDLINKCOM for linking shared objects.

DLINKFLAGPREFIX
    DLINKFLAGPREFIX.

DLINKFLAGS
    List of linker flags. See also $SHDLINKFLAGS for linking shared objects.

DLINKFLAGSUFFIX
    DLINKFLAGSUFFIX.

DOCBOOK_DEFAULT_XSL_EPUB
    The default XSLT file for the DocbookEpub builder within the current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_HTML
    The default XSLT file for the DocbookHtml builder within the current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_HTMLCHUNKED
    The default XSLT file for the DocbookHtmlChunked builder within the current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_HTMLHELP
    The default XSLT file for the DocbookHtmlhelp builder within the current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_MAN
    The default XSLT file for the DocbookMan builder within the current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_PDF
    The default XSLT file for the DocbookPdf builder within the current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_SLIDESHTML
    The default XSLT file for the DocbookSlidesHtml builder within the current environment, if no other XSLT gets specified via keyword.

DOCBOOK_DEFAULT_XSL_SLIDESPDF
    The default XSLT file for the DocbookSlidesPdf builder within the current environment, if no other XSLT gets specified via keyword.

DOCBOOK_FOP
    The path to the PDF renderer fop or xep, if one of them is installed (fop gets checked first).

DOCBOOK_FOPCOM
    The full command-line for the PDF renderer fop or xep.

DOCBOOK_FOPCOMSTR
    The string displayed when a renderer like fop or xep is used to create PDF output from an XML file.

DOCBOOK_FOPFLAGS
    Additonal command-line flags for the PDF renderer fop or xep.

DOCBOOK_XMLLINT
    The path to the external executable xmllint, if it's installed. Note, that this is only used as last fallback for resolving XIncludes, if no lxml Python binding can be imported in the current system.

DOCBOOK_XMLLINTCOM
    The full command-line for the external executable xmllint.

DOCBOOK_XMLLINTCOMSTR
    The string displayed when xmllint is used to resolve XIncludes for a given XML file.

DOCBOOK_XMLLINTFLAGS
    Additonal command-line flags for the external executable xmllint.

DOCBOOK_XSLTPROC
    The path to the external executable xsltproc (or saxon, xalan), if one of them is installed. Note, that this is only used as last fallback for XSL transformations, if no lxml Python binding can be imported in the current system.

DOCBOOK_XSLTPROCCOM
    The full command-line for the external executable xsltproc (or saxon, xalan).

DOCBOOK_XSLTPROCCOMSTR
    The string displayed when xsltproc is used to transform an XML file via a given XSLT stylesheet.

DOCBOOK_XSLTPROCFLAGS
    Additonal command-line flags for the external executable xsltproc (or saxon, xalan).

DOCBOOK_XSLTPROCPARAMS
    Additonal parameters that are not intended for the XSLT processor executable, but the XSL processing itself. By default, they get appended at the end of the command line for saxon and saxon-xslt, respectively.

DPATH
    List of paths to search for import modules.

DRPATHPREFIX
    DRPATHPREFIX.

DRPATHSUFFIX
    DRPATHSUFFIX.

DSUFFIXES
    The list of suffixes of files that will be scanned for imported D package files. The default list is ['.d'].

DVERPREFIX
    DVERPREFIX.

DVERSIONS
    List of version tags to enable when compiling.

DVERSUFFIX
    DVERSUFFIX.

DVIPDF
    The TeX DVI file to PDF file converter.

DVIPDFCOM
    The command line used to convert TeX DVI files into a PDF file.

DVIPDFCOMSTR
    The string displayed when a TeX DVI file is converted into a PDF file. If this is not set, then $DVIPDFCOM (the command line) is displayed.

DVIPDFFLAGS
    General options passed to the TeX DVI file to PDF file converter.

DVIPS
    The TeX DVI file to PostScript converter.

DVIPSFLAGS
    General options passed to the TeX DVI file to PostScript converter.

ENV
    The execution environment - a dictionary of environment variables used when SCons invokes external commands to build targets defined in this construction environment. When $ENV is passed to a command, all list values are assumed to be path lists and are joined using the search path separator. Any other non-string values are coerced to a string.

    Note that by default SCons does not propagate the environment in effect when you execute scons (the "shell environment") to the execution environment. This is so that builds will be guaranteed repeatable regardless of the environment variables set at the time scons is invoked. If you want to propagate a shell environment variable to the commands executed to build target files, you must do so explicitly. A common example is the system PATH environment variable, so that scons will find utilities the same way as the invoking shell (or other process):

        import os
        env = Environment(ENV={'PATH': os.environ['PATH']})

    Although it is usually not recommended, you can propagate the entire shell environment in one go:

        import os
        env = Environment(ENV=os.environ.copy())

ESCAPE
    A function that will be called to escape shell special characters in command lines. The function should take one argument: the command line string to escape; and should return the escaped command line.

F03
    The Fortran 03 compiler. You should normally set the $FORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $F03 if you need to use a specific compiler or compiler version for Fortran 03 files.

F03COM
    The command line used to compile a Fortran 03 source file to an object file. You only need to set $F03COM if you need to use a specific command line for Fortran 03 files. You should normally set the $FORTRANCOM variable, which specifies the default command line for all Fortran versions.

F03COMSTR
    If set, the string displayed when a Fortran 03 source file is compiled to an object file. If not set, then $F03COM or $FORTRANCOM (the command line) is displayed.

F03FILESUFFIXES
    The list of file extensions for which the F03 dialect will be used. By default, this is ['.f03']

F03FLAGS
    General user-specified options that are passed to the Fortran 03 compiler. Note that this variable does not contain -I (or similar) include search path options that scons generates automatically from $F03PATH. See $_F03INCFLAGS below, for the variable that expands to those options. You only need to set $F03FLAGS if you need to define specific user options for Fortran 03 files. You should normally set the $FORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

_F03INCFLAGS
    An automatically-generated construction variable containing the Fortran 03 compiler command-line options for specifying directories to be searched for include files. The value of $_F03INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $F03PATH.

F03PATH
    The list of directories that the Fortran 03 compiler will search for include directories. The implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in $F03FLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in $F03PATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #: You only need to set $F03PATH if you need to define a specific include path for Fortran 03 files. You should normally set the $FORTRANPATH variable, which specifies the include path for the default Fortran compiler for all Fortran versions.

        env = Environment(F03PATH='#/include')

    The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(F03PATH=include)

    The directory list will be added to command lines through the automatically-generated $_F03INCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $F03PATH. Any command lines you define that need the F03PATH directory list should include $_F03INCFLAGS:

        env = Environment(F03COM="my_compiler $_F03INCFLAGS -c -o $TARGET $SOURCE")

F03PPCOM
    The command line used to compile a Fortran 03 source file to an object file after first running the file through the C preprocessor. Any options specified in the $F03FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $F03PPCOM if you need to use a specific C-preprocessor command line for Fortran 03 files. You should normally set the $FORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

F03PPCOMSTR
    If set, the string displayed when a Fortran 03 source file is compiled to an object file after first running the file through the C preprocessor. If not set, then $F03PPCOM or $FORTRANPPCOM (the command line) is displayed.

F03PPFILESUFFIXES
    The list of file extensions for which the compilation + preprocessor pass for F03 dialect will be used. By default, this is empty.

F08
    The Fortran 08 compiler. You should normally set the $FORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $F08 if you need to use a specific compiler or compiler version for Fortran 08 files.

F08COM
    The command line used to compile a Fortran 08 source file to an object file. You only need to set $F08COM if you need to use a specific command line for Fortran 08 files. You should normally set the $FORTRANCOM variable, which specifies the default command line for all Fortran versions.

F08COMSTR
    If set, the string displayed when a Fortran 08 source file is compiled to an object file. If not set, then $F08COM or $FORTRANCOM (the command line) is displayed.

F08FILESUFFIXES
    The list of file extensions for which the F08 dialect will be used. By default, this is ['.f08']

F08FLAGS
    General user-specified options that are passed to the Fortran 08 compiler. Note that this variable does not contain -I (or similar) include search path options that scons generates automatically from $F08PATH. See $_F08INCFLAGS below, for the variable that expands to those options. You only need to set $F08FLAGS if you need to define specific user options for Fortran 08 files. You should normally set the $FORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

_F08INCFLAGS
    An automatically-generated construction variable containing the Fortran 08 compiler command-line options for specifying directories to be searched for include files. The value of $_F08INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $F08PATH.

F08PATH
    The list of directories that the Fortran 08 compiler will search for include directories. The implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in $F08FLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in $F08PATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #: You only need to set $F08PATH if you need to define a specific include path for Fortran 08 files. You should normally set the $FORTRANPATH variable, which specifies the include path for the default Fortran compiler for all Fortran versions.

        env = Environment(F08PATH='#/include')

    The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(F08PATH=include)

    The directory list will be added to command lines through the automatically-generated $_F08INCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $F08PATH. Any command lines you define that need the F08PATH directory list should include $_F08INCFLAGS:

        env = Environment(F08COM="my_compiler $_F08INCFLAGS -c -o $TARGET $SOURCE")

F08PPCOM
    The command line used to compile a Fortran 08 source file to an object file after first running the file through the C preprocessor. Any options specified in the $F08FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $F08PPCOM if you need to use a specific C-preprocessor command line for Fortran 08 files. You should normally set the $FORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

F08PPCOMSTR
    If set, the string displayed when a Fortran 08 source file is compiled to an object file after first running the file through the C preprocessor. If not set, then $F08PPCOM or $FORTRANPPCOM (the command line) is displayed.

F08PPFILESUFFIXES
    The list of file extensions for which the compilation + preprocessor pass for F08 dialect will be used. By default, this is empty.

F77
    The Fortran 77 compiler. You should normally set the $FORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $F77 if you need to use a specific compiler or compiler version for Fortran 77 files.

F77COM
    The command line used to compile a Fortran 77 source file to an object file. You only need to set $F77COM if you need to use a specific command line for Fortran 77 files. You should normally set the $FORTRANCOM variable, which specifies the default command line for all Fortran versions.

F77COMSTR
    If set, the string displayed when a Fortran 77 source file is compiled to an object file. If not set, then $F77COM or $FORTRANCOM (the command line) is displayed.

F77FILESUFFIXES
    The list of file extensions for which the F77 dialect will be used. By default, this is ['.f77']

F77FLAGS
    General user-specified options that are passed to the Fortran 77 compiler. Note that this variable does not contain -I (or similar) include search path options that scons generates automatically from $F77PATH. See $_F77INCFLAGS below, for the variable that expands to those options. You only need to set $F77FLAGS if you need to define specific user options for Fortran 77 files. You should normally set the $FORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

_F77INCFLAGS
    An automatically-generated construction variable containing the Fortran 77 compiler command-line options for specifying directories to be searched for include files. The value of $_F77INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $F77PATH.

F77PATH
    The list of directories that the Fortran 77 compiler will search for include directories. The implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in $F77FLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in $F77PATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #: You only need to set $F77PATH if you need to define a specific include path for Fortran 77 files. You should normally set the $FORTRANPATH variable, which specifies the include path for the default Fortran compiler for all Fortran versions.

        env = Environment(F77PATH='#/include')

    The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(F77PATH=include)

    The directory list will be added to command lines through the automatically-generated $_F77INCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $F77PATH. Any command lines you define that need the F77PATH directory list should include $_F77INCFLAGS:

        env = Environment(F77COM="my_compiler $_F77INCFLAGS -c -o $TARGET $SOURCE")

F77PPCOM
    The command line used to compile a Fortran 77 source file to an object file after first running the file through the C preprocessor. Any options specified in the $F77FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $F77PPCOM if you need to use a specific C-preprocessor command line for Fortran 77 files. You should normally set the $FORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

F77PPCOMSTR
    If set, the string displayed when a Fortran 77 source file is compiled to an object file after first running the file through the C preprocessor. If not set, then $F77PPCOM or $FORTRANPPCOM (the command line) is displayed.

F77PPFILESUFFIXES
    The list of file extensions for which the compilation + preprocessor pass for F77 dialect will be used. By default, this is empty.

F90
    The Fortran 90 compiler. You should normally set the $FORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $F90 if you need to use a specific compiler or compiler version for Fortran 90 files.

F90COM
    The command line used to compile a Fortran 90 source file to an object file. You only need to set $F90COM if you need to use a specific command line for Fortran 90 files. You should normally set the $FORTRANCOM variable, which specifies the default command line for all Fortran versions.

F90COMSTR
    If set, the string displayed when a Fortran 90 source file is compiled to an object file. If not set, then $F90COM or $FORTRANCOM (the command line) is displayed.

F90FILESUFFIXES
    The list of file extensions for which the F90 dialect will be used. By default, this is ['.f90']

F90FLAGS
    General user-specified options that are passed to the Fortran 90 compiler. Note that this variable does not contain -I (or similar) include search path options that scons generates automatically from $F90PATH. See $_F90INCFLAGS below, for the variable that expands to those options. You only need to set $F90FLAGS if you need to define specific user options for Fortran 90 files. You should normally set the $FORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

_F90INCFLAGS
    An automatically-generated construction variable containing the Fortran 90 compiler command-line options for specifying directories to be searched for include files. The value of $_F90INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $F90PATH.

F90PATH
    The list of directories that the Fortran 90 compiler will search for include directories. The implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in $F90FLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in $F90PATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #: You only need to set $F90PATH if you need to define a specific include path for Fortran 90 files. You should normally set the $FORTRANPATH variable, which specifies the include path for the default Fortran compiler for all Fortran versions.

        env = Environment(F90PATH='#/include')

    The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(F90PATH=include)

    The directory list will be added to command lines through the automatically-generated $_F90INCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $F90PATH. Any command lines you define that need the F90PATH directory list should include $_F90INCFLAGS:

        env = Environment(F90COM="my_compiler $_F90INCFLAGS -c -o $TARGET $SOURCE")

F90PPCOM
    The command line used to compile a Fortran 90 source file to an object file after first running the file through the C preprocessor. Any options specified in the $F90FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $F90PPCOM if you need to use a specific C-preprocessor command line for Fortran 90 files. You should normally set the $FORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

F90PPCOMSTR
    If set, the string displayed when a Fortran 90 source file is compiled after first running the file through the C preprocessor. If not set, then $F90PPCOM or $FORTRANPPCOM (the command line) is displayed.

F90PPFILESUFFIXES
    The list of file extensions for which the compilation + preprocessor pass for F90 dialect will be used. By default, this is empty.

F95
    The Fortran 95 compiler. You should normally set the $FORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $F95 if you need to use a specific compiler or compiler version for Fortran 95 files.

F95COM
    The command line used to compile a Fortran 95 source file to an object file. You only need to set $F95COM if you need to use a specific command line for Fortran 95 files. You should normally set the $FORTRANCOM variable, which specifies the default command line for all Fortran versions.

F95COMSTR
    If set, the string displayed when a Fortran 95 source file is compiled to an object file. If not set, then $F95COM or $FORTRANCOM (the command line) is displayed.

F95FILESUFFIXES
    The list of file extensions for which the F95 dialect will be used. By default, this is ['.f95']

F95FLAGS
    General user-specified options that are passed to the Fortran 95 compiler. Note that this variable does not contain -I (or similar) include search path options that scons generates automatically from $F95PATH. See $_F95INCFLAGS below, for the variable that expands to those options. You only need to set $F95FLAGS if you need to define specific user options for Fortran 95 files. You should normally set the $FORTRANFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

_F95INCFLAGS
    An automatically-generated construction variable containing the Fortran 95 compiler command-line options for specifying directories to be searched for include files. The value of $_F95INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $F95PATH.

F95PATH
    The list of directories that the Fortran 95 compiler will search for include directories. The implicit dependency scanner will search these directories for include files. Don't explicitly put include directory arguments in $F95FLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in $F95PATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #: You only need to set $F95PATH if you need to define a specific include path for Fortran 95 files. You should normally set the $FORTRANPATH variable, which specifies the include path for the default Fortran compiler for all Fortran versions.

        env = Environment(F95PATH='#/include')

    The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(F95PATH=include)

    The directory list will be added to command lines through the automatically-generated $_F95INCFLAGS construction variable, which is constructed by appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $F95PATH. Any command lines you define that need the F95PATH directory list should include $_F95INCFLAGS:

        env = Environment(F95COM="my_compiler $_F95INCFLAGS -c -o $TARGET $SOURCE")

F95PPCOM
    The command line used to compile a Fortran 95 source file to an object file after first running the file through the C preprocessor. Any options specified in the $F95FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $F95PPCOM if you need to use a specific C-preprocessor command line for Fortran 95 files. You should normally set the $FORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

F95PPCOMSTR
    If set, the string displayed when a Fortran 95 source file is compiled to an object file after first running the file through the C preprocessor. If not set, then $F95PPCOM or $FORTRANPPCOM (the command line) is displayed.

F95PPFILESUFFIXES
    The list of file extensions for which the compilation + preprocessor pass for F95 dialect will be used. By default, this is empty.

File
    A function that converts a string into a File instance relative to the target being built.

FILE_ENCODING
    File encoding used for files written by Textfile and Substfile. Set to "utf-8" by default.

    New in version 4.5.0.

FORTRAN
    The default Fortran compiler for all versions of Fortran.

FORTRANCOM
    The command line used to compile a Fortran source file to an object file. By default, any options specified in the $FORTRANFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS construction variables are included on this command line.

FORTRANCOMMONFLAGS
    General user-specified options that are passed to the Fortran compiler. Similar to $FORTRANFLAGS, but this construction variable is applied to all dialects.

    New in version 4.4.

FORTRANCOMSTR
    If set, the string displayed when a Fortran source file is compiled to an object file. If not set, then $FORTRANCOM (the command line) is displayed.

FORTRANFILESUFFIXES
    The list of file extensions for which the FORTRAN dialect will be used. By default, this is ['.f', '.for', '.ftn']

FORTRANFLAGS
    General user-specified options for the FORTRAN dialect that are passed to the Fortran compiler. Note that this variable does not contain -I (or similar) include or module search path options that scons generates automatically from $FORTRANPATH. See $_FORTRANINCFLAGS and $_FORTRANMODFLAG for the construction variables that expand those options.

_FORTRANINCFLAGS
    An automatically-generated construction variable containing the Fortran compiler command-line options for specifying directories to be searched for include files and module files. The value of $_FORTRANINCFLAGS is created by respectively prepending and appending $INCPREFIX and $INCSUFFIX to the beginning and end of each directory in $FORTRANPATH.

FORTRANMODDIR
    Directory location where the Fortran compiler should place any module files it generates. This variable is empty, by default. Some Fortran compilers will internally append this directory in the search path for module files, as well.

FORTRANMODDIRPREFIX
    The prefix used to specify a module directory on the Fortran compiler command line. This will be prepended to the beginning of the directory in the $FORTRANMODDIR construction variables when the $_FORTRANMODFLAG variables is automatically generated.

FORTRANMODDIRSUFFIX
    The suffix used to specify a module directory on the Fortran compiler command line. This will be appended to the end of the directory in the $FORTRANMODDIR construction variables when the $_FORTRANMODFLAG variables is automatically generated.

_FORTRANMODFLAG
    An automatically-generated construction variable containing the Fortran compiler command-line option for specifying the directory location where the Fortran compiler should place any module files that happen to get generated during compilation. The value of $_FORTRANMODFLAG is created by respectively prepending and appending $FORTRANMODDIRPREFIX and $FORTRANMODDIRSUFFIX to the beginning and end of the directory in $FORTRANMODDIR.

FORTRANMODPREFIX
    The module file prefix used by the Fortran compiler. SCons assumes that the Fortran compiler follows the quasi-standard naming convention for module files of module_name.mod. As a result, this variable is left empty, by default. For situations in which the compiler does not necessarily follow the normal convention, the user may use this variable. Its value will be appended to every module file name as scons attempts to resolve dependencies.

FORTRANMODSUFFIX
    The module file suffix used by the Fortran compiler. SCons assumes that the Fortran compiler follows the quasi-standard naming convention for module files of module_name.mod. As a result, this variable is set to ".mod", by default. For situations in which the compiler does not necessarily follow the normal convention, the user may use this variable. Its value will be appended to every module file name as scons attempts to resolve dependencies.

FORTRANPATH
    The list of directories that the Fortran compiler will search for include files and (for some compilers) module files. The Fortran implicit dependency scanner will search these directories for include files (but not module files since they are autogenerated and, as such, may not actually exist at the time the scan takes place). Don't explicitly put include directory arguments in FORTRANFLAGS because the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in FORTRANPATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use #:

        env = Environment(FORTRANPATH='#/include')

    The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(FORTRANPATH=include)

    The directory list will be added to command lines through the automatically-generated $_FORTRANINCFLAGS construction variable, which is constructed by respectively prepending and appending the values of the $INCPREFIX and $INCSUFFIX construction variables to the beginning and end of each directory in $FORTRANPATH. Any command lines you define that need the FORTRANPATH directory list should include $_FORTRANINCFLAGS:

        env = Environment(FORTRANCOM="my_compiler $_FORTRANINCFLAGS -c -o $TARGET $SOURCE")

FORTRANPPCOM
    The command line used to compile a Fortran source file to an object file after first running the file through the C preprocessor. By default, any options specified in the $FORTRANFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS construction variables are included on this command line.

FORTRANPPCOMSTR
    If set, the string displayed when a Fortran source file is compiled to an object file after first running the file through the C preprocessor. If not set, then $FORTRANPPCOM (the command line) is displayed.

FORTRANPPFILESUFFIXES
    The list of file extensions for which the compilation + preprocessor pass for FORTRAN dialect will be used. By default, this is ['.fpp', '.FPP']

FORTRANSUFFIXES
    The list of suffixes of files that will be scanned for Fortran implicit dependencies (INCLUDE lines and USE statements). The default list is:

        [".f", ".F", ".for", ".FOR", ".ftn", ".FTN", ".fpp", ".FPP",
        ".f77", ".F77", ".f90", ".F90", ".f95", ".F95"]

FRAMEWORKPATH
    On Mac OS X with gcc, a list containing the paths to search for frameworks. Used by the compiler to find framework-style includes like #include <Fmwk/Header.h>. Used by the linker to find user-specified frameworks when linking (see $FRAMEWORKS). For example:

        env.AppendUnique(FRAMEWORKPATH='#myframeworkdir')

    will add

        ... -Fmyframeworkdir

    to the compiler and linker command lines.

_FRAMEWORKPATH
    On Mac OS X with gcc, an automatically-generated construction variable containing the linker command-line options corresponding to $FRAMEWORKPATH.

FRAMEWORKPATHPREFIX
    On Mac OS X with gcc, the prefix to be used for the FRAMEWORKPATH entries. (see $FRAMEWORKPATH). The default value is -F.

FRAMEWORKPREFIX
    On Mac OS X with gcc, the prefix to be used for linking in frameworks (see $FRAMEWORKS). The default value is -framework.

FRAMEWORKS
    On Mac OS X with gcc, a list of the framework names to be linked into a program or shared library or bundle. The default value is the empty list. For example:

        env.AppendUnique(FRAMEWORKS=Split('System Cocoa SystemConfiguration'))

_FRAMEWORKS
    On Mac OS X with gcc, an automatically-generated construction variable containing the linker command-line options for linking with FRAMEWORKS.

FRAMEWORKSFLAGS
    On Mac OS X with gcc, general user-supplied frameworks options to be added at the end of a command line building a loadable module. (This has been largely superseded by the $FRAMEWORKPATH, $FRAMEWORKPATHPREFIX, $FRAMEWORKPREFIX and $FRAMEWORKS variables described above.)

GS
    The Ghostscript program used to, for example, convert PostScript to PDF files.

GSCOM
    The full Ghostscript command line used for the conversion process. Its default value is “$GS $GSFLAGS -sOutputFile=$TARGET $SOURCES”.

GSCOMSTR
    The string displayed when Ghostscript is called for the conversion process. If this is not set (the default), then $GSCOM (the command line) is displayed.

GSFLAGS
    General options passed to the Ghostscript program, when converting PostScript to PDF files for example. Its default value is “-dNOPAUSE -dBATCH -sDEVICE=pdfwrite”

HOST_ARCH
    The name of the host hardware architecture used to create this construction environment. The platform code sets this when initializing (see $PLATFORM and the platform argument to Environment). Note the detected name of the architecture may not be identical to that returned by the Python platform.machine method.

    On the win32 platform, if the Microsoft Visual C++ compiler is available, msvc tool setup is done using $HOST_ARCH and $TARGET_ARCH. Changing the values at any later time will not cause the tool to be reinitialized. Valid host arch values are x86 and arm for 32-bit hosts and amd64, arm64, and x86_64 for 64-bit hosts.

    Should be considered immutable. $HOST_ARCH is not currently used by other platforms, but the option is reserved to do so in future

HOST_OS
    The name of the host operating system for the platform used to create this construction environment. The platform code sets this when initializing (see $PLATFORM and the platform argument to Environment).

    Should be considered immutable. $HOST_OS is not currently used by SCons, but the option is reserved to do so in future

IDLSUFFIXES
    The list of suffixes of files that will be scanned for IDL implicit dependencies (#include or import lines). The default list is:

        [".idl", ".IDL"]

IMPLIBNOVERSIONSYMLINKS
    Used to override $SHLIBNOVERSIONSYMLINKS/$LDMODULENOVERSIONSYMLINKS when creating versioned import library for a shared library/loadable module. If not defined, then $SHLIBNOVERSIONSYMLINKS/$LDMODULENOVERSIONSYMLINKS is used to determine whether to disable symlink generation or not.

IMPLIBPREFIX
    The prefix used for import library names. For example, cygwin uses import libraries (libfoo.dll.a) in pair with dynamic libraries (cygfoo.dll). The cyglink linker sets $IMPLIBPREFIX to 'lib' and $SHLIBPREFIX to 'cyg'.

IMPLIBSUFFIX
    The suffix used for import library names. For example, cygwin uses import libraries (libfoo.dll.a) in pair with dynamic libraries (cygfoo.dll). The cyglink linker sets $IMPLIBSUFFIX to '.dll.a' and $SHLIBSUFFIX to '.dll'.

IMPLIBVERSION
    Used to override $SHLIBVERSION/$LDMODULEVERSION when generating versioned import library for a shared library/loadable module. If undefined, the $SHLIBVERSION/$LDMODULEVERSION is used to determine the version of versioned import library.

IMPLICIT_COMMAND_DEPENDENCIES
    Controls whether or not SCons will add implicit dependencies for the commands executed to build targets.

    By default, SCons will add to each target an implicit dependency on the command represented by the first argument of any command line it executes (which is typically the command itself). By setting such a dependency, SCons can determine that a target should be rebuilt if the command changes, such as when a compiler is upgraded to a new version. The specific file for the dependency is found by searching the PATH variable in the ENV dictionary in the construction environment used to execute the command. The default is the same as setting the construction variable $IMPLICIT_COMMAND_DEPENDENCIES to a True-like value (“true”, “yes”, or “1” - but not a number greater than one, as that has a different meaning).

    Action strings can be segmented by the use of an AND operator, &&. In a segemented string, each segment is a separate “command line”, these are run sequentially until one fails or the entire sequence has been executed. If an action string is segmented, then the selected behavior of $IMPLICIT_COMMAND_DEPENDENCIES is applied to each segment.

    If $IMPLICIT_COMMAND_DEPENDENCIES is set to a False-like value (“none”, “false”, “no”, “0”, etc.), then the implicit dependency will not be added to the targets built with that construction environment.

    If $IMPLICIT_COMMAND_DEPENDENCIES is set to “2” or higher, then that number of arguments in the command line will be scanned for relative or absolute paths. If any are present, they will be added as implicit dependencies to the targets built with that construction environment. The first argument in the command line will be searched for using the PATH variable in the ENV dictionary in the construction environment used to execute the command. The other arguments will only be found if they are absolute paths or valid paths relative to the working directory.

    If $IMPLICIT_COMMAND_DEPENDENCIES is set to “all”, then all arguments in the command line will be scanned for relative or absolute paths. If any are present, they will be added as implicit dependencies to the targets built with that construction environment. The first argument in the command line will be searched for using the PATH variable in the ENV dictionary in the construction environment used to execute the command. The other arguments will only be found if they are absolute paths or valid paths relative to the working directory.

        env = Environment(IMPLICIT_COMMAND_DEPENDENCIES=False)

INCPREFIX
    The prefix used to specify an include directory on the C compiler command line. This will be prepended to each directory in the $CPPPATH and $FORTRANPATH construction variables when the $_CPPINCFLAGS and $_FORTRANINCFLAGS variables are automatically generated.

INCSUFFIX
    The suffix used to specify an include directory on the C compiler command line. This will be appended to each directory in the $CPPPATH and $FORTRANPATH construction variables when the $_CPPINCFLAGS and $_FORTRANINCFLAGS variables are automatically generated.

INSTALL
    A function to be called to install a file into a destination file name. The default function copies the file into the destination (and sets the destination file's mode and permission bits to match the source file's). The function takes the following arguments:

        def install(dest, source, env):

    dest is the path name of the destination file. source is the path name of the source file. env is the construction environment (a dictionary of construction values) in force for this file installation.

INSTALLSTR
    The string displayed when a file is installed into a destination file name. The default is:

        Install file: "$SOURCE" as "$TARGET"

INTEL_C_COMPILER_VERSION
    Set by the intelc Tool to the major version number of the Intel C compiler selected for use.

JAR
    The Java archive tool.

JARCHDIR
    The directory to which the Java archive tool should change (using the -C option).

JARCOM
    The command line used to call the Java archive tool.

JARCOMSTR
    The string displayed when the Java archive tool is called If this is not set, then $JARCOM (the command line) is displayed.

        env = Environment(JARCOMSTR="JARchiving $SOURCES into $TARGET")

JARFLAGS
    General options passed to the Java archive tool. By default this is set to cf to create the necessary jar file.

JARSUFFIX
    The suffix for Java archives: .jar by default.

JAVABOOTCLASSPATH
    Specifies the location of the bootstrap class files. Can be specified as a string or Node object, or as a list of strings or Node objects.

    The value will be added to the JDK command lines via the -bootclasspath option, which requires a system-specific search path separator. This will be supplied by SCons as needed when it constructs the command line if $JAVABOOTCLASSPATH is provided in list form. If $JAVABOOTCLASSPATH is a single string containing search path separator characters (: for POSIX systems or ; for Windows), it will not be modified; and so is inherently system-specific; to supply the path in a system-independent manner, give $JAVABOOTCLASSPATH as a list of paths instead.

        Note
        Can only be used when compiling for releases prior to JDK 9.

JAVAC
    The Java compiler.

JAVACCOM
    The command line used to compile a directory tree containing Java source files to corresponding Java class files. Any options specified in the $JAVACFLAGS construction variable are included on this command line.

JAVACCOMSTR
    The string displayed when compiling a directory tree of Java source files to corresponding Java class files. If this is not set, then $JAVACCOM (the command line) is displayed.

        env = Environment(JAVACCOMSTR="Compiling class files $TARGETS from $SOURCES")

JAVACFLAGS
    General options that are passed to the Java compiler.

JAVACLASSDIR
    The directory in which Java class files may be found. This is stripped from the beginning of any Java .class file names supplied to the JavaH builder.

JAVACLASSPATH
    Specifies the class search path for the JDK tools. Can be specified as a string or Node object, or as a list of strings or Node objects. Class path entries may be directory names to search for class files or packages, pathnames to archives (.jar or .zip) containing classes, or paths ending in a "base name wildcard" character (*), which matches files in that directory with a .jar suffix. See the Java documentation for more details.

    The value will be added to the JDK command lines via the -classpath option, which requires a system-specific search path separator. This will be supplied by SCons as needed when it constructs the command line if $JAVACLASSPATH is provided in list form. If $JAVACLASSPATH is a single string containing search path separator characters (: for POSIX systems or ; for Windows), it will be split on the separator into a list of individual paths for dependency scanning purposes. It will not be modified for JDK command-line usage, so such a string is inherently system-specific; to supply the path in a system-independent manner, give $JAVACLASSPATH as a list of paths instead.

        Note
        SCons always supplies a -sourcepath when invoking the Java compiler javac, regardless of the setting of $JAVASOURCEPATH, as it passes the path(s) to the source(s) supplied in the call to the Java builder via -sourcepath . From the documentation of the standard Java toolkit for javac: “If not compiling code for modules, if the --source-path or -sourcepath option is not specified, then the user class path is also searched for source files.” Since -sourcepath is always supplied, javac will not use the contents of the value of $JAVACLASSPATH when searching for sources.

JAVACLASSSUFFIX
    The suffix for Java class files; .class by default.

JAVAH
    The Java generator for C header and stub files.

JAVAHCOM
    The command line used to generate C header and stub files from Java classes. Any options specified in the $JAVAHFLAGS construction variable are included on this command line.

JAVAHCOMSTR
    The string displayed when C header and stub files are generated from Java classes. If this is not set, then $JAVAHCOM (the command line) is displayed.

        env = Environment(JAVAHCOMSTR="Generating header/stub file(s) $TARGETS from $SOURCES")

JAVAHFLAGS
    General options passed to the C header and stub file generator for Java classes.

JAVAINCLUDES
    Include path for Java header files (such as jni.h).

JAVAPROCESSORPATH
    Specifies the location of the annotation processor class files. Can be specified as a string or Node object, or as a list of strings or Node objects.

    The value will be added to the JDK command lines via the -processorpath option, which requires a system-specific search path separator. This will be supplied by SCons as needed when it constructs the command line if $JAVAPROCESSORPATH is provided in list form. If $JAVAPROCESSORPATH is a single string containing search path separator characters (: for POSIX systems or ; for Windows), it will not be modified; and so is inherently system-specific; to supply the path in a system-independent manner, give $JAVAPROCESSORPATH as a list of paths instead.

    New in version 4.5.0

JAVASOURCEPATH
    Specifies the list of directories that will be searched for input (source) .java files. Can be specified as a string or Node object, or as a list of strings or Node objects.

    The value will be added to the JDK command lines via the -sourcepath option, which requires a system-specific search path separator, This will be supplied by SCons as needed when it constructs the command line if $JAVASOURCEPATH is provided in list form. If $JAVASOURCEPATH is a single string containing search path separator characters (: for POSIX systems or ; for Windows), it will not be modified, and so is inherently system-specific; to supply the path in a system-independent manner, give $JAVASOURCEPATH as a list of paths instead.

    Note that the specified directories are only added to the command line via the -sourcepath option. SCons does not currently search the $JAVASOURCEPATH directories for dependent .java files.

JAVASUFFIX
    The suffix for Java files; .java by default.

JAVAVERSION
    Specifies the Java version being used by the Java builder. Set this to specify the version of Java targeted by the javac compiler. This is sometimes necessary because Java 1.5 changed the file names that are created for nested anonymous inner classes, which can cause a mismatch with the files that SCons expects will be generated by the javac compiler. Setting $JAVAVERSION to a version greater than 1.4 makes SCons realize that a build with such a compiler is actually up to date. The default is 1.4.

    While this is not primarily intended for selecting one version of the Java compiler vs. another, it does have that effect on the Windows platform. A more precise approach is to set $JAVAC (and related construction variables for related utilities) to the path to the specific Java compiler you want, if that is not the default compiler. On non-Windows platforms, the alternatives system may provide a way to adjust the default Java compiler without having to specify explicit paths.

LATEX
    The LaTeX structured formatter and typesetter.

LATEXCOM
    The command line used to call the LaTeX structured formatter and typesetter.

LATEXCOMSTR
    The string displayed when calling the LaTeX structured formatter and typesetter. If this is not set, then $LATEXCOM (the command line) is displayed.

        env = Environment(LATEXCOMSTR = "Building $TARGET from LaTeX input $SOURCES")

LATEXFLAGS
    General options passed to the LaTeX structured formatter and typesetter.

LATEXRETRIES
    The maximum number of times that LaTeX will be re-run if the .log generated by the $LATEXCOM command indicates that there are undefined references. The default is to try to resolve undefined references by re-running LaTeX up to three times.

LATEXSUFFIXES
    The list of suffixes of files that will be scanned for LaTeX implicit dependencies (\include or \import files). The default list is:

        [".tex", ".ltx", ".latex"]

LDMODULE
    The linker for building loadable modules. By default, this is the same as $SHLINK.

LDMODULECOM
    The command line for building loadable modules. On Mac OS X, this uses the $LDMODULE, $LDMODULEFLAGS and $FRAMEWORKSFLAGS variables. On other systems, this is the same as $SHLINK.

LDMODULECOMSTR
    If set, the string displayed when building loadable modules. If not set, then $LDMODULECOM (the command line) is displayed.

LDMODULEEMITTER
    Contains the emitter specification for the LoadableModule builder. The manpage section "Builder Objects" contains general information on specifying emitters.

LDMODULEFLAGS
    General user options passed to the linker for building loadable modules.

LDMODULENOVERSIONSYMLINKS
    Instructs the LoadableModule builder to not automatically create symlinks for versioned modules. Defaults to $SHLIBNOVERSIONSYMLINKS

LDMODULEPREFIX
    The prefix used for loadable module file names. On Mac OS X, this is null; on other systems, this is the same as $SHLIBPREFIX.

_LDMODULESONAME
    A macro that automatically generates loadable module's SONAME based on $TARGET, $LDMODULEVERSION and $LDMODULESUFFIX. Used by LoadableModule builder when the linker tool supports SONAME (e.g. gnulink).

LDMODULESUFFIX
    The suffix used for loadable module file names. On Mac OS X, this is null; on other systems, this is the same as $SHLIBSUFFIX.

LDMODULEVERSION
    When this construction variable is defined, a versioned loadable module is created by LoadableModule builder. This activates the $_LDMODULEVERSIONFLAGS and thus modifies the $LDMODULECOM as required, adds the version number to the library name, and creates the symlinks that are needed. $LDMODULEVERSION versions should exist in the same format as $SHLIBVERSION.

_LDMODULEVERSIONFLAGS
    This macro automatically introduces extra flags to $LDMODULECOM when building versioned LoadableModule (that is when $LDMODULEVERSION is set). _LDMODULEVERSIONFLAGS usually adds $SHLIBVERSIONFLAGS and some extra dynamically generated options (such as -Wl,-soname=$_LDMODULESONAME). It is unused by plain (unversioned) loadable modules.

LDMODULEVERSIONFLAGS
    Extra flags added to $LDMODULECOM when building versioned LoadableModule. These flags are only used when $LDMODULEVERSION is set.

LEX
    The lexical analyzer generator.

LEX_HEADER_FILE
    If supplied, generate a C header file with the name taken from this variable. Will be emitted as a --header-file= command-line option. Use this in preference to including --header-file= in $LEXFLAGS directly.

LEX_TABLES_FILE
    If supplied, write the lex tables to a file with the name taken from this variable. Will be emitted as a --tables-file= command-line option. Use this in preference to including --tables-file= in $LEXFLAGS directly.

LEXCOM
    The command line used to call the lexical analyzer generator to generate a source file.

LEXCOMSTR
    The string displayed when generating a source file using the lexical analyzer generator. If this is not set, then $LEXCOM (the command line) is displayed.

        env = Environment(LEXCOMSTR="Lex'ing $TARGET from $SOURCES")

LEXFLAGS
    General options passed to the lexical analyzer generator. In addition to passing the value on during invocation, the lex tool also examines this construction variable for options which cause additional output files to be generated, and adds those to the target list. Recognized for this purpose are GNU flex options --header-file= and --tables-file=; the output file is named by the option argument.

    Note that files specified by --header-file= and --tables-file= may not be properly handled by SCons in all situations. Consider using $LEX_HEADER_FILE and $LEX_TABLES_FILE instead.

LEXUNISTD
    Used only on windows environments to set a lex flag to prevent 'unistd.h' from being included. The default value is '--nounistd'.

_LIBDIRFLAGS
    An automatically-generated construction variable containing the linker command-line options for specifying directories to be searched for library. The value of $_LIBDIRFLAGS is created by respectively prepending and appending $LIBDIRPREFIX and $LIBDIRSUFFIX to each directory in $LIBPATH.

LIBDIRPREFIX
    The prefix used to specify a library directory on the linker command line. This will be prepended to each directory in the $LIBPATH construction variable when the $_LIBDIRFLAGS variable is automatically generated.

LIBDIRSUFFIX
    The suffix used to specify a library directory on the linker command line. This will be appended to each directory in the $LIBPATH construction variable when the $_LIBDIRFLAGS variable is automatically generated.

LIBEMITTER
    Contains the emitter specification for the StaticLibrary builder. The manpage section "Builder Objects" contains general information on specifying emitters.

_LIBFLAGS
    An automatically-generated construction variable containing the linker command-line options for specifying libraries to be linked with the resulting target. The value of $_LIBFLAGS is created by respectively prepending and appending $LIBLINKPREFIX and $LIBLINKSUFFIX to each filename in $LIBS.

LIBLINKPREFIX
    The prefix used to specify a library to link on the linker command line. This will be prepended to each library in the $LIBS construction variable when the $_LIBFLAGS variable is automatically generated.

LIBLINKSUFFIX
    The suffix used to specify a library to link on the linker command line. This will be appended to each library in the $LIBS construction variable when the $_LIBFLAGS variable is automatically generated.

LIBLITERALPREFIX
    If the linker supports command line syntax directing that the argument specifying a library should be searched for literally (without modification), $LIBLITERALPREFIX can be set to that indicator. For example, the GNU linker follows this rule: “ -l:foo searches the library path for a filename called foo, without converting it to libfoo.so or libfoo.a. ” If $LIBLITERALPREFIX is set, SCons will not transform a string-valued entry in $LIBS that starts with that string. The entry will still be surrounded with $LIBLINKPREFIX and $LIBLINKSUFFIX on the command line. This is useful, for example, in directing that a static library be used when both a static and dynamic library are available and linker policy is to prefer dynamic libraries. Compared to the example in $LIBS,

        env.Append(LIBS=":libmylib.a")

    will let the linker select that specific (static) library name if found in the library search path. This differs from using a File object to specify the static library, as the latter bypasses the library search path entirely.

LIBPATH
    The list of directories that will be searched for libraries specified by the $LIBS construction variable. $LIBPATH should be a list of path strings, or a single string, not a pathname list joined by Python's os.pathsep. Do not put library search directives directly into $LINKFLAGS or $SHLINKFLAGS as the result will be non-portable.

    Note: directory names in $LIBPATH will be looked-up relative to the directory of the SConscript file when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use the # prefix:

        env = Environment(LIBPATH='#/libs')

    The directory look-up can also be forced using the Dir function:

        libs = Dir('libs')
        env = Environment(LIBPATH=libs)

    The directory list will be added to command lines through the automatically-generated $_LIBDIRFLAGS construction variable, which is constructed by respectively prepending and appending the values of the $LIBDIRPREFIX and $LIBDIRSUFFIX construction variables to each directory in $LIBPATH. Any command lines you define that need the $LIBPATH directory list should include $_LIBDIRFLAGS:

        env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

LIBPREFIX
    The prefix used for (static) library file names. A default value is set for each platform (posix, win32, os2, etc.), but the value is overridden by individual tools (ar, mslib, sgiar, sunar, tlib, etc.) to reflect the names of the libraries they create.

LIBPREFIXES
    A list of all legal prefixes for library file names on the current platform. When searching for library dependencies, SCons will look for files with these prefixes, the base library name, and suffixes from the $LIBSUFFIXES list.

LIBS
    The list of libraries that will be added to the link line for linking with any executable program, shared library, or loadable module created by the construction environment or override.

    For portability, a string-valued library name should include only the base library name, without prefixes such as lib or suffixes such as .so or .dll. SCons will attempt to strip prefixes from the $LIBPREFIXES list and suffixes from the $LIBSUFFIXES list, but depending on that behavior will make the build less portable: for example, on a POSIX system, no attempt will be made to strip a suffix like .dll. Library name strings in $LIBS should not include a path component: instead use $LIBPATH to direct the compiler to look for libraries in those paths, plus any default paths the linker searches in. If $LIBLITERALPREFIX is set to a non-empty string, then a string-valued $LIBS entry that starts with $LIBLITERALPREFIX will cause the rest of the entry to be searched for for unmodified, but respecting normal library search paths (this is an exception to the guideline above about leaving off the prefix/suffix from the library name).

    If a $LIBS entry is a Node object (either as returned by a previous Builder call, or as the result of an explicit call to File), the pathname from that Node will be added to $_LIBFLAGS, and thus to the link line, unmodified - without adding $LIBLINKPREFIX or $LIBLINKSUFFIX. Such entries are searched for literally (including any path component); the library search paths are not used. For example:

        env.Append(LIBS=File('/tmp/mylib.so'))

    For each Builder call that causes linking with libraries, SCons will add the libraries in the setting of $LIBS in effect at that moment to the dependecy graph as dependencies of the target being generated.

    The library list will transformed to command line arguments through the automatically-generated $_LIBFLAGS construction variable which is constructed by respectively prepending and appending the values of the $LIBLINKPREFIX and $LIBLINKSUFFIX construction variables to each library name.

    Any command lines you define yourself that need the libraries from $LIBS should include $_LIBFLAGS (as well as $_LIBDIRFLAGS) rather than $LIBS. For example:

        env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

LIBSUFFIX
    The suffix used for (static) library file names. A default value is set for each platform (posix, win32, os2, etc.), but the value is overridden by individual tools (ar, mslib, sgiar, sunar, tlib, etc.) to reflect the names of the libraries they create.

LIBSUFFIXES
    A list of all legal suffixes for library file names. on the current platform. When searching for library dependencies, SCons will look for files with prefixes from the $LIBPREFIXES list, the base library name, and these suffixes.

LICENSE
    The abbreviated name, preferably the SPDX code, of the license under which this project is released (GPL-3.0, LGPL-2.1, BSD-2-Clause etc.). See http://www.opensource.org/licenses/alphabetical[8] for a list of license names and SPDX codes.

    See the Package builder.

LINESEPARATOR
    The separator used by the Substfile and Textfile builders. This value is used between sources when constructing the target. It defaults to the current system line separator.

LINGUAS_FILE
    The $LINGUAS_FILE defines file(s) containing list of additional linguas to be processed by POInit, POUpdate or MOFiles builders. It also affects Translate builder. If the variable contains a string, it defines name of the list file. The $LINGUAS_FILE may be a list of file names as well. If $LINGUAS_FILE is set to True (or non-zero numeric value), the list will be read from default file named LINGUAS.

LINK
    The linker. See also $SHLINK for linking shared objects.

    On POSIX systems (those using the link tool), you should normally not change this value as it defaults to a "smart" linker tool which selects a compiler driver matching the type of source files in use. So for example, if you set $CXX to a specific compiler name, and are compiling C++ sources, the smartlink function will automatically select the same compiler for linking.

LINKCOM
    The command line used to link object files into an executable. See also $SHLINKCOM for linking shared objects.

LINKCOMSTR
    If set, the string displayed when object files are linked into an executable. If not set, then $LINKCOM (the command line) is displayed. See also $SHLINKCOMSTR. for linking shared objects.

        env = Environment(LINKCOMSTR = "Linking $TARGET")

LINKFLAGS
    General user options passed to the linker. Note that this variable should not contain -l (or similar) options for linking with the libraries listed in $LIBS, nor -L (or similar) library search path options that scons generates automatically from $LIBPATH. See $_LIBFLAGS above, for the variable that expands to library-link options, and $_LIBDIRFLAGS above, for the variable that expands to library search path options. See also $SHLINKFLAGS. for linking shared objects.

M4
    The M4 macro preprocessor.

M4COM
    The command line used to pass files through the M4 macro preprocessor.

M4COMSTR
    The string displayed when a file is passed through the M4 macro preprocessor. If this is not set, then $M4COM (the command line) is displayed.

M4FLAGS
    General options passed to the M4 macro preprocessor.

MAKEINDEX
    The makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

MAKEINDEXCOM
    The command line used to call the makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

MAKEINDEXCOMSTR
    The string displayed when calling the makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter. If this is not set, then $MAKEINDEXCOM (the command line) is displayed.

MAKEINDEXFLAGS
    General options passed to the makeindex generator for the TeX formatter and typesetter and the LaTeX structured formatter and typesetter.

MAXLINELENGTH
    The maximum number of characters allowed on an external command line. On Win32 systems, link lines longer than this many characters are linked via a temporary file name.

MIDL
    The Microsoft IDL compiler.

MIDLCOM
    The command line used to pass files to the Microsoft IDL compiler.

MIDLCOMSTR
    The string displayed when the Microsoft IDL compiler is called. If this is not set, then $MIDLCOM (the command line) is displayed.

MIDLFLAGS
    General options passed to the Microsoft IDL compiler.

MOSUFFIX
    Suffix used for MO files (default: '.mo'). See msgfmt tool and MOFiles builder.

MSGFMT
    Absolute path to msgfmt(1) binary, found by Detect(). See msgfmt tool and MOFiles builder.

MSGFMTCOM
    Complete command line to run msgfmt(1) program. See msgfmt tool and MOFiles builder.

MSGFMTCOMSTR
    String to display when msgfmt(1) is invoked (default: '', which means ``print $MSGFMTCOM''). See msgfmt tool and MOFiles builder.

MSGFMTFLAGS
    Additional flags to msgfmt(1). See msgfmt tool and MOFiles builder.

MSGINIT
    Path to msginit(1) program (found via Detect()). See msginit tool and POInit builder.

MSGINITCOM
    Complete command line to run msginit(1) program. See msginit tool and POInit builder.

MSGINITCOMSTR
    String to display when msginit(1) is invoked (default: '', which means ``print $MSGINITCOM''). See msginit tool and POInit builder.

MSGINITFLAGS
    List of additional flags to msginit(1) (default: []). See msginit tool and POInit builder.

_MSGINITLOCALE
    Internal ``macro''. Computes locale (language) name based on target filename (default: '${TARGET.filebase}').

    See msginit tool and POInit builder.

MSGMERGE
    Absolute path to msgmerge(1) binary as found by Detect(). See msgmerge tool and POUpdate builder.

MSGMERGECOM
    Complete command line to run msgmerge(1) command. See msgmerge tool and POUpdate builder.

MSGMERGECOMSTR
    String to be displayed when msgmerge(1) is invoked (default: '', which means ``print $MSGMERGECOM''). See msgmerge tool and POUpdate builder.

MSGMERGEFLAGS
    Additional flags to msgmerge(1) command. See msgmerge tool and POUpdate builder.

MSSDK_DIR
    The directory containing the Microsoft SDK (either Platform SDK or Windows SDK) to be used for compilation.

MSSDK_VERSION
    The version string of the Microsoft SDK (either Platform SDK or Windows SDK) to be used for compilation. Supported versions include 6.1, 6.0A, 6.0, 2003R2 and 2003R1.

MSVC_BATCH
    When set to any true value, specifies that SCons should batch compilation of object files when calling the Microsoft Visual C++ compiler. All compilations of source files from the same source directory that generate target files in a same output directory and were configured in SCons using the same construction environment will be built in a single call to the compiler. Only source files that have changed since their object files were built will be passed to each compiler invocation (via the $CHANGED_SOURCES construction variable). Any compilations where the object (target) file base name (minus the .obj) does not match the source file base name will be compiled separately.

MSVC_NOTFOUND_POLICY
    Specify the scons behavior when the Microsoft Visual C++ compiler is not detected.

    The $MSVC_NOTFOUND_POLICY specifies the scons behavior when no msvc versions are detected or when the requested msvc version is not detected.

    The valid values for $MSVC_NOTFOUND_POLICY and the corresponding scons behavior are:

    'Error' or 'Exception'
        Raise an exception when no msvc versions are detected or when the requested msvc version is not detected.

    'Warning' or 'Warn'
        Issue a warning and continue when no msvc versions are detected or when the requested msvc version is not detected. Depending on usage, this could result in build failure(s).

    'Ignore' or 'Suppress'
        Take no action and continue when no msvc versions are detected or when the requested msvc version is not detected. Depending on usage, this could result in build failure(s).

    Note: in addition to the camel case values shown above, lower case and upper case values are accepted as well.

    The $MSVC_NOTFOUND_POLICY is applied when any of the following conditions are satisfied:

        • $MSVC_VERSION is specified, the default tools list is implicitly defined (i.e., the tools list is not specified), and the default tools list contains one or more of the msvc tools.

        • $MSVC_VERSION is specified, the default tools list is explicitly specified (e.g., tools=['default']), and the default tools list contains one or more of the msvc tools.

        • A non-default tools list is specified that contains one or more of the msvc tools (e.g., tools=['msvc', 'mslink']).

    The $MSVC_NOTFOUND_POLICY is ignored when any of the following conditions are satisfied:

        • $MSVC_VERSION is not specified and the default tools list is implicitly defined (i.e., the tools list is not specified).

        • $MSVC_VERSION is not specified and the default tools list is explicitly specified (e.g., tools=['default']).

        • A non-default tool list is specified that does not contain any of the msvc tools (e.g., tools=['mingw']).

    Important usage details:

        • $MSVC_NOTFOUND_POLICY must be passed as an argument to the Environment constructor when an msvc tool (e.g., msvc, msvs, etc.) is loaded via the default tools list or via a tools list passed to the Environment constructor. Otherwise, $MSVC_NOTFOUND_POLICY must be set before the first msvc tool is loaded into the environment.

    When $MSVC_NOTFOUND_POLICY is not specified, the default scons behavior is to issue a warning and continue subject to the conditions listed above. The default scons behavior may change in the future.

    New in version 4.4

MSVC_SCRIPT_ARGS
    Pass user-defined arguments to the Microsoft Visual C++ batch file determined via autodetection.

    $MSVC_SCRIPT_ARGS is available for msvc batch file arguments that do not have first-class support via construction variables or when there is an issue with the appropriate construction variable validation. When available, it is recommended to use the appropriate construction variables (e.g., $MSVC_TOOLSET_VERSION) rather than $MSVC_SCRIPT_ARGS arguments.

    The valid values for $MSVC_SCRIPT_ARGS are: None, a string, or a list of strings.

    The $MSVC_SCRIPT_ARGS value is converted to a scalar string (i.e., "flattened"). The resulting scalar string, if not empty, is passed as an argument to the msvc batch file determined via autodetection subject to the validation conditions listed below.

    $MSVC_SCRIPT_ARGS is ignored when the value is None and when the result from argument conversion is an empty string. The validation conditions below do not apply.

    An exception is raised when any of the following conditions are satisfied:

        • $MSVC_SCRIPT_ARGS is specified for Visual Studio 2013 and earlier.

        • Multiple SDK version arguments (e.g., '10.0.20348.0') are specified in $MSVC_SCRIPT_ARGS.

        • $MSVC_SDK_VERSION is specified and an SDK version argument (e.g., '10.0.20348.0') is specified in $MSVC_SCRIPT_ARGS. Multiple SDK version declarations via $MSVC_SDK_VERSION and $MSVC_SCRIPT_ARGS are not allowed.

        • Multiple toolset version arguments (e.g., '-vcvars_ver=14.29') are specified in $MSVC_SCRIPT_ARGS.

        • $MSVC_TOOLSET_VERSION is specified and a toolset version argument (e.g., '-vcvars_ver=14.29') is specified in $MSVC_SCRIPT_ARGS. Multiple toolset version declarations via $MSVC_TOOLSET_VERSION and $MSVC_SCRIPT_ARGS are not allowed.

        • Multiple spectre library arguments (e.g., '-vcvars_spectre_libs=spectre') are specified in $MSVC_SCRIPT_ARGS.

        • $MSVC_SPECTRE_LIBS is enabled and a spectre library argument (e.g., '-vcvars_spectre_libs=spectre') is specified in $MSVC_SCRIPT_ARGS. Multiple spectre library declarations via $MSVC_SPECTRE_LIBS and $MSVC_SCRIPT_ARGS are not allowed.

        • Multiple UWP arguments (e.g., uwp or store) are specified in $MSVC_SCRIPT_ARGS.

        • $MSVC_UWP_APP is enabled and a UWP argument (e.g., uwp or store) is specified in $MSVC_SCRIPT_ARGS. Multiple UWP declarations via $MSVC_UWP_APP and $MSVC_SCRIPT_ARGS are not allowed.

    Example 1 - A Visual Studio 2022 build with an SDK version and a toolset version specified with a string argument:

        env = Environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS='10.0.20348.0 -vcvars_ver=14.29.30133')

    Example 2 - A Visual Studio 2022 build with an SDK version and a toolset version specified with a list argument:

        env = Environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS=['10.0.20348.0', '-vcvars_ver=14.29.30133'])

    Important usage details:

        • $MSVC_SCRIPT_ARGS must be passed as an argument to the Environment constructor when an msvc tool (e.g., msvc, msvs, etc.) is loaded via the default tools list or via a tools list passed to the Environment constructor. Otherwise, $MSVC_SCRIPT_ARGS must be set before the first msvc tool is loaded into the environment.

        • Other than checking for multiple declarations as described above, $MSVC_SCRIPT_ARGS arguments are not validated.

        • Erroneous, inconsistent, and/or version incompatible $MSVC_SCRIPT_ARGS arguments are likely to result in build failures for reasons that are not readily apparent and may be difficult to diagnose. The burden is on the user to ensure that the arguments provided to the msvc batch file are valid, consistent and compatible with the version of msvc selected.

    New in version 4.4

MSVC_SCRIPTERROR_POLICY
    Specify the scons behavior when Microsoft Visual C++ batch file errors are detected.

    The $MSVC_SCRIPTERROR_POLICY specifies the scons behavior when msvc batch file errors are detected. When $MSVC_SCRIPTERROR_POLICY is not specified, the default scons behavior is to suppress msvc batch file error messages.

    The root cause of msvc build failures may be difficult to diagnose. In these situations, setting the scons behavior to issue a warning when msvc batch file errors are detected may produce additional diagnostic information.

    The valid values for $MSVC_SCRIPTERROR_POLICY and the corresponding scons behavior are:

    'Error' or 'Exception'
        Raise an exception when msvc batch file errors are detected.

    'Warning' or 'Warn'
        Issue a warning when msvc batch file errors are detected.

    'Ignore' or 'Suppress'
        Suppress msvc batch file error messages.

        New in version 4.4

    Note: in addition to the camel case values shown above, lower case and upper case values are accepted as well.

    Example 1 - A Visual Studio 2022 build with user-defined script arguments:

        env = environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS=['8.1', 'store', '-vcvars_ver=14.1'])
        env.Program('hello', ['hello.c'], CCFLAGS='/MD', LIBS=['kernel32', 'user32', 'runtimeobject'])

    Example 1 - Output fragment:

        ...
        link /nologo /OUT:_build001\hello.exe kernel32.lib user32.lib runtimeobject.lib _build001\hello.obj
        LINK : fatal error LNK1104: cannot open file 'MSVCRT.lib'
        ...

    Example 2 - A Visual Studio 2022 build with user-defined script arguments and the script error policy set to issue a warning when msvc batch file errors are detected:

        env = environment(MSVC_VERSION='14.3', MSVC_SCRIPT_ARGS=['8.1', 'store', '-vcvars_ver=14.1'], MSVC_SCRIPTERROR_POLICY='warn')
        env.Program('hello', ['hello.c'], CCFLAGS='/MD', LIBS=['kernel32', 'user32', 'runtimeobject'])

    Example 2 - Output fragment:

        ...
        scons: warning: vc script errors detected:
        [ERROR:vcvars.bat] The UWP Application Platform requires a Windows 10 SDK.
        [ERROR:vcvars.bat] WindowsSdkDir = "C:\Program Files (x86)\Windows Kits\8.1\"
        [ERROR:vcvars.bat] host/target architecture is not supported : { x64 , x64 }
        ...
        link /nologo /OUT:_build001\hello.exe kernel32.lib user32.lib runtimeobject.lib _build001\hello.obj
        LINK : fatal error LNK1104: cannot open file 'MSVCRT.lib'

    Important usage details:

        • $MSVC_SCRIPTERROR_POLICY must be passed as an argument to the Environment constructor when an msvc tool (e.g., msvc, msvs, etc.) is loaded via the default tools list or via a tools list passed to the Environment constructor. Otherwise, $MSVC_SCRIPTERROR_POLICY must be set before the first msvc tool is loaded into the environment.

        • Due to scons implementation details, not all Windows system environment variables are propagated to the environment in which the msvc batch file is executed. Depending on Visual Studio version and installation options, non-fatal msvc batch file error messages may be generated for ancillary tools which may not affect builds with the msvc compiler. For this reason, caution is recommended when setting the script error policy to raise an exception (e.g., 'Error').

    New in version 4.4

MSVC_SDK_VERSION
    Build with a specific version of the Microsoft Software Development Kit (SDK).

    The valid values for $MSVC_SDK_VERSION are: None or a string containing the requested SDK version (e.g., '10.0.20348.0').

    $MSVC_SDK_VERSION is ignored when the value is None and when the value is an empty string. The validation conditions below do not apply.

    An exception is raised when any of the following conditions are satisfied:

        • $MSVC_SDK_VERSION is specified for Visual Studio 2013 and earlier.

        • $MSVC_SDK_VERSION is specified and an SDK version argument is specified in $MSVC_SCRIPT_ARGS. Multiple SDK version declarations via $MSVC_SDK_VERSION and $MSVC_SCRIPT_ARGS are not allowed.

        • The $MSVC_SDK_VERSION specified does not match any of the supported formats:

            • '10.0.XXXXX.Y' [SDK 10.0]

            • '8.1' [SDK 8.1]

        • The system folder for the corresponding $MSVC_SDK_VERSION version is not found. The requested SDK version does not appear to be installed.

        • The $MSVC_SDK_VERSION version does not appear to support the requested platform type (i.e., UWP or Desktop). The requested SDK version platform type components do not appear to be installed.

        • The $MSVC_SDK_VERSION version is 8.1, the platform type is UWP, and the build tools selected are from Visual Studio 2017 and later (i.e., $MSVC_VERSION must be '14.0' or $MSVC_TOOLSET_VERSION must be '14.0').

    Example 1 - A Visual Studio 2022 build with a specific Windows SDK version:

        env = Environment(MSVC_VERSION='14.3', MSVC_SDK_VERSION='10.0.20348.0')

    Example 2 - A Visual Studio 2022 build with a specific SDK version for the Universal Windows Platform:

        env = Environment(MSVC_VERSION='14.3', MSVC_SDK_VERSION='10.0.20348.0', MSVC_UWP_APP=True)

    Important usage details:

        • $MSVC_SDK_VERSION must be passed as an argument to the Environment constructor when an msvc tool (e.g., msvc, msvs, etc.) is loaded via the default tools list or via a tools list passed to the Environment constructor. Otherwise, $MSVC_SDK_VERSION must be set before the first msvc tool is loaded into the environment.

        • Should a SDK 10.0 version be installed that does not follow the naming scheme above, the SDK version will need to be specified via $MSVC_SCRIPT_ARGS until the version number validation format can be extended.

        • Should an exception be raised indicating that the SDK version is not found, verify that the requested SDK version is installed with the necessary platform type components.

        • There is a known issue with the Microsoft libraries when the target architecture is ARM64 and a Windows 11 SDK (version '10.0.22000.0' and later) is used with the v141 build tools and older v142 toolsets (versions '14.28.29333' and earlier). Should build failures arise with these combinations of settings due to unresolved symbols in the Microsoft libraries, $MSVC_SDK_VERSION may be employed to specify a Windows 10 SDK (e.g., '10.0.20348.0') for the build.

    New in version 4.4

MSVC_SPECTRE_LIBS
    Build with the spectre-mitigated Microsoft Visual C++ libraries.

    The valid values for $MSVC_SPECTRE_LIBS are: True, False, or None.

    When $MSVC_SPECTRE_LIBS is enabled (i.e., True), the Microsoft Visual C++ environment will include the paths to the spectre-mitigated implementations of the Microsoft Visual C++ libraries.

    An exception is raised when any of the following conditions are satisfied:

        • $MSVC_SPECTRE_LIBS is enabled for Visual Studio 2015 and earlier.

        • $MSVC_SPECTRE_LIBS is enabled and a spectre library argument is specified in $MSVC_SCRIPT_ARGS. Multiple spectre library declarations via $MSVC_SPECTRE_LIBS and $MSVC_SCRIPT_ARGS are not allowed.

        • $MSVC_SPECTRE_LIBS is enabled and the platform type is UWP. There are no spectre-mitigated libraries for Universal Windows Platform (UWP) applications or components.

    Example - A Visual Studio 2022 build with spectre mitigated Microsoft Visual C++ libraries:

        env = Environment(MSVC_VERSION='14.3', MSVC_SPECTRE_LIBS=True)

    Important usage details:

        • $MSVC_SPECTRE_LIBS must be passed as an argument to the Environment constructor when an msvc tool (e.g., msvc, msvs, etc.) is loaded via the default tools list or via a tools list passed to the Environment constructor. Otherwise, $MSVC_SPECTRE_LIBS must be set before the first msvc tool is loaded into the environment.

        • Additional compiler switches (e.g., /Qspectre) are necessary for including spectre mitigations when building user artifacts. Refer to the Visual Studio documentation for details.

        • The existence of the spectre libraries host architecture and target architecture folders are not verified when $MSVC_SPECTRE_LIBS is enabled which could result in build failures. The burden is on the user to ensure the requisite libraries with spectre mitigations are installed.

    New in version 4.4

MSVC_TOOLSET_VERSION
    Build with a specific Microsoft Visual C++ toolset version.

    Specifying $MSVC_TOOLSET_VERSION does not affect the autodetection and selection of msvc instances. The $MSVC_TOOLSET_VERSION is applied after an msvc instance is selected. This could be the default version of msvc if $MSVC_VERSION is not specified.

    The valid values for $MSVC_TOOLSET_VERSION are: None or a string containing the requested toolset version (e.g., '14.29').

    $MSVC_TOOLSET_VERSION is ignored when the value is None and when the value is an empty string. The validation conditions below do not apply.

    An exception is raised when any of the following conditions are satisfied:

        • $MSVC_TOOLSET_VERSION is specified for Visual Studio 2015 and earlier.

        • $MSVC_TOOLSET_VERSION is specified and a toolset version argument is specified in $MSVC_SCRIPT_ARGS. Multiple toolset version declarations via $MSVC_TOOLSET_VERSION and $MSVC_SCRIPT_ARGS are not allowed.

        • The $MSVC_TOOLSET_VERSION specified does not match any of the supported formats:

            • 'XX.Y'

            • 'XX.YY'

            • 'XX.YY.ZZZZZ'

            • 'XX.YY.Z' to 'XX.YY.ZZZZ' [scons extension not directly supported by the msvc batch files and may be removed in the future]

            • 'XX.YY.ZZ.N' [SxS format]

            • 'XX.YY.ZZ.NN' [SxS format]

        • The major msvc version prefix (i.e., 'XX.Y') of the $MSVC_TOOLSET_VERSION specified is for Visual Studio 2013 and earlier (e.g., '12.0').

        • The major msvc version prefix (i.e., 'XX.Y') of the $MSVC_TOOLSET_VERSION specified is greater than the msvc version selected (e.g., '99.0').

        • A system folder for the corresponding $MSVC_TOOLSET_VERSION version is not found. The requested toolset version does not appear to be installed.

    Toolset selection details:

        • When $MSVC_TOOLSET_VERSION is not an SxS version number or a full toolset version number: the first toolset version, ranked in descending order, that matches the $MSVC_TOOLSET_VERSION prefix is selected.

        • When $MSVC_TOOLSET_VERSION is specified using the major msvc version prefix (i.e., 'XX.Y') and the major msvc version is that of the latest release of Visual Studio, the selected toolset version may not be the same as the default Microsoft Visual C++ toolset version.

        In the latest release of Visual Studio, the default Microsoft Visual C++ toolset version is not necessarily the toolset with the largest version number.

    Example 1 - A default Visual Studio build with a partial toolset version specified:

        env = Environment(MSVC_TOOLSET_VERSION='14.2')

    Example 2 - A default Visual Studio build with a partial toolset version specified:

        env = Environment(MSVC_TOOLSET_VERSION='14.29')

    Example 3 - A Visual Studio 2022 build with a full toolset version specified:

        env = Environment(MSVC_VERSION='14.3', MSVC_TOOLSET_VERSION='14.29.30133')

    Example 4 - A Visual Studio 2022 build with an SxS toolset version specified:

        env = Environment(MSVC_VERSION='14.3', MSVC_TOOLSET_VERSION='14.29.16.11')

    Important usage details:

        • $MSVC_TOOLSET_VERSION must be passed as an argument to the Environment constructor when an msvc tool (e.g., msvc, msvs, etc.) is loaded via the default tools list or via a tools list passed to the Environment constructor. Otherwise, $MSVC_TOOLSET_VERSION must be set before the first msvc tool is loaded into the environment.

        • The existence of the toolset host architecture and target architecture folders are not verified when $MSVC_TOOLSET_VERSION is specified which could result in build failures. The burden is on the user to ensure the requisite toolset target architecture build tools are installed.

    New in version 4.4

MSVC_USE_SCRIPT
    Use a batch script to set up the Microsoft Visual C++ compiler.

    If set to the name of a Visual Studio .bat file (e.g. vcvars.bat), SCons will run that batch file instead of the auto-detected one, and extract the relevant variables from the result (typically %INCLUDE%, %LIB%, and %PATH%) for supplying to the build. This can be useful to force the use of a compiler version that SCons does not detect. $MSVC_USE_SCRIPT_ARGS provides arguments passed to this script.

    Setting $MSVC_USE_SCRIPT to None bypasses the Visual Studio autodetection entirely; use this if you are running SCons in a Visual Studio cmd window and importing the shell's environment variables - that is, if you are sure everything is set correctly already and you don't want SCons to change anything.

    $MSVC_USE_SCRIPT ignores $MSVC_VERSION and $TARGET_ARCH.

    Changed in version 4.4: new $MSVC_USE_SCRIPT_ARGS provides a way to pass arguments.

MSVC_USE_SCRIPT_ARGS
    Provides arguments passed to the script $MSVC_USE_SCRIPT.

    New in version 4.4

MSVC_USE_SETTINGS
    Use a dictionary to set up the Microsoft Visual C++ compiler.

    $MSVC_USE_SETTINGS is ignored when $MSVC_USE_SCRIPT is defined and/or when $MSVC_USE_SETTINGS is set to None.

    The dictionary is used to populate the environment with the relevant variables (typically %INCLUDE%, %LIB%, and %PATH%) for supplying to the build. This can be useful to force the use of a compiler environment that SCons does not configure correctly. This is an alternative to manually configuring the environment when bypassing Visual Studio autodetection entirely by setting $MSVC_USE_SCRIPT to None.

    Here is an example of configuring a build environment using the Microsoft Visual C++ compiler included in the Microsoft SDK on a 64-bit host and building for a 64-bit architecture:

        # Microsoft SDK 6.0 (MSVC 8.0): 64-bit host and 64-bit target
        msvc_use_settings = {
            "PATH": [
                "C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Bin\\x64",
                "C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Bin\\x64",
                "C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Bin",
                "C:\\Windows\\Microsoft.NET\\Framework\\v2.0.50727",
                "C:\\Windows\\system32",
                "C:\\Windows",
                "C:\\Windows\\System32\\Wbem",
                "C:\\Windows\\System32\\WindowsPowerShell\\v1.0\\"
            ],
            "INCLUDE": [
                "C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Include",
                "C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Include\\Sys",
                "C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Include",
                "C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Include\\gl",
            ],
            "LIB": [
                "C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\VC\\Lib\\x64",
                "C:\\Program Files\\Microsoft SDKs\\Windows\\v6.0\\Lib\\x64",
            ],
            "LIBPATH": [],
            "VSCMD_ARG_app_plat": [],
            "VCINSTALLDIR": [],
            "VCToolsInstallDir": []
        }
        # Specifying MSVC_VERSION is recommended
        env = Environment(MSVC_VERSION='8.0', MSVC_USE_SETTINGS=msvc_use_settings)

    Important usage details:

        • $MSVC_USE_SETTINGS must be passed as an argument to the Environment constructor when an msvc tool (e.g., msvc, msvs, etc.) is loaded via the default tools list or via a tools list passed to the Environment constructor. Otherwise, $MSVC_USE_SETTINGS must be set before the first msvc tool is loaded into the environment.

        • The dictionary content requirements are based on the internal msvc implementation and therefore may change at any time. The burden is on the user to ensure the dictionary contents are minimally sufficient to ensure successful builds.

    New in version 4.4

MSVC_UWP_APP
    Build with the Universal Windows Platform (UWP) application Microsoft Visual C++ libraries.

    The valid values for $MSVC_UWP_APP are: True, '1', False, '0', or None.

    When $MSVC_UWP_APP is enabled (i.e., True or '1'), the Microsoft Visual C++ environment will be set up to point to the Windows Store compatible libraries and Microsoft Visual C++ runtimes. In doing so, any libraries that are built will be able to be used in a UWP App and published to the Windows Store.

    An exception is raised when any of the following conditions are satisfied:

        • $MSVC_UWP_APP is enabled for Visual Studio 2013 and earlier.

        • $MSVC_UWP_APP is enabled and a UWP argument is specified in $MSVC_SCRIPT_ARGS. Multiple UWP declarations via $MSVC_UWP_APP and $MSVC_SCRIPT_ARGS are not allowed.

    Example - A Visual Studio 2022 build for the Universal Windows Platform:

        env = Environment(MSVC_VERSION='14.3', MSVC_UWP_APP=True)

    Important usage details:

        • $MSVC_UWP_APP must be passed as an argument to the Environment constructor when an msvc tool (e.g., msvc, msvs, etc.) is loaded via the default tools list or via a tools list passed to the Environment constructor. Otherwise, $MSVC_UWP_APP must be set before the first msvc tool is loaded into the environment.

        • The existence of the UWP libraries is not verified when $MSVC_UWP_APP is enabled which could result in build failures. The burden is on the user to ensure the requisite UWP libraries are installed.

MSVC_VERSION
    A string to select the preferred version of Microsoft Visual C++. If the specified version is unavailable and/or unknown to SCons, a warning is issued showing the versions actually discovered, and the build will eventually fail indicating a missing compiler binary. If $MSVC_VERSION is not set, SCons will (by default) select the latest version of Microsoft Visual C++ installed on your system (excluding any preview versions).

        Note
        In order to take effect, $MSVC_VERSION must be set before the initial Microsoft Visual C++ compiler discovery takes place. Discovery happens, at the latest, during the first call to the Environment function, unless a tools list is specified which excludes the entire Microsoft Visual C++ toolchain - that is, omits "defaults" and any specific tool module that refers to parts of the toolchain (msvc, mslink, masm, midl and msvs). In this case, detection is deferred until any one of those tool modules is invoked manually. The following two examples illustrate this:

            # MSVC_VERSION set as Environment is created
            env = Environment(MSVC_VERSION='14.2')
            # Initialization deferred with empty tools, triggered manually
            env = Environment(tools=[])
            env['MSVC_VERSION'] = '14.2
            env.Tool('msvc')
            env.Tool('mslink')
            env.Tool('msvs')

    The valid values for $MSVC_VERSION represent major versions of the compiler, except that versions ending in Exp refer to "Express" or "Express for Desktop" Visual Studio editions. Values that do not look like a valid compiler version string are not supported.

    The following table shows the correspondence of $MSVC_VERSION values to various version indicators ('x' is used as a placeholder for a single digit that can vary).
    SCons Key | Visual C++ Version | _MSVC_VER | Visual Studio Product | MSBuild / Visual Studio
    "14.3" | 14.3x | 193x | Visual Studio 2022 | 17.x, 17.1x
    "14.2" | 14.2x | 192x | Visual Studio 2019 | 16.x, 16.1x
    "14.1" | 14.1 or 14.1x | 191x | Visual Studio 2017 | 15.x
    "14.1Exp" | 14.1 or 14.1x | 191x | Visual Studio 2017 Express | 15.x
    "14.0" | 14.0 | 1900 | Visual Studio 2015 | 14.0
    "14.0Exp" | 14.0 | 1900 | Visual Studio 2015 Express | 14.0
    "12.0" | 12.0 | 1800 | Visual Studio 2013 | 12.0
    "12.0Exp" | 12.0 | 1800 | Visual Studio 2013 Express | 12.0
    "11.0" | 11.0 | 1700 | Visual Studio 2012 | 11.0
    "11.0Exp" | 11.0 | 1700 | Visual Studio 2012 Express | 11.0
    "10.0" | 10.0 | 1600 | Visual Studio 2010 | 10.0
    "10.0Exp" | 10.0 | 1600 | Visual C++ Express 2010 | 10.0
    "9.0" | 9.0 | 1500 | Visual Studio 2008 | 9.0
    "9.0Exp" | 9.0 | 1500 | Visual C++ Express 2008 | 9.0
    "8.0" | 8.0 | 1400 | Visual Studio 2005 | 8.0
    "8.0Exp" | 8.0 | 1400 | Visual C++ Express 2005 | 8.0
    "7.1" | 7.1 | 1300 | Visual Studio .NET 2003 | 7.1
    "7.0" | 7.0 | 1200 | Visual Studio .NET 2002 | 7.0
    "6.0" | 6.0 | 1100 | Visual Studio 6.0 | 6.0

        Note

            • It is not necessary to install a Visual Studio IDE to build with SCons (for example, you can install only Build Tools), but when a Visual Studio IDE is installed, additional builders such as MSVSSolution and MSVSProject become available and correspond to the specified versions.

            • Versions ending in Exp refer to historical "Express" or "Express for Desktop" Visual Studio editions, which had feature limitations compared to the full editions. It is only necessary to specify the Exp suffix to select the express edition when both express and non-express editions of the same product are installed simulaneously. The Exp suffix is unnecessary, but accepted, when only the express edition is installed.

    The compilation environment can be further or more precisely specified through the use of several other construction variables: see the descriptions of $MSVC_TOOLSET_VERSION, $MSVC_SDK_VERSION, $MSVC_USE_SCRIPT, $MSVC_USE_SCRIPT_ARGS, and $MSVC_USE_SETTINGS.

MSVS
    When the Microsoft Visual Studio tools are initialized, they set up this dictionary with the following keys:

    VERSION
        the version of MSVS being used (can be set via $MSVC_VERSION)

    VERSIONS
        the available versions of MSVS installed

    VCINSTALLDIR
        installed directory of Microsoft Visual C++

    VSINSTALLDIR
        installed directory of Visual Studio

    FRAMEWORKDIR
        installed directory of the .NET framework

    FRAMEWORKVERSIONS
        list of installed versions of the .NET framework, sorted latest to oldest.

    FRAMEWORKVERSION
        latest installed version of the .NET framework

    FRAMEWORKSDKDIR
        installed location of the .NET SDK.

    PLATFORMSDKDIR
        installed location of the Platform SDK.

    PLATFORMSDK_MODULES
        dictionary of installed Platform SDK modules, where the dictionary keys are keywords for the various modules, and the values are 2-tuples where the first is the release date, and the second is the version number.

    If a value is not set, it was not available in the registry. Visual Studio 2017 and later do not use the registry for primary storage of this information, so typically for these versions only PROJECTSUFFIX and SOLUTIONSUFFIX will be set.

MSVS_ARCH
    Sets the architecture for which the generated project(s) should build.

    The default value is x86. amd64 is also supported by SCons for most Visual Studio versions. Since Visual Studio 2015 arm is supported, and since Visual Studio 2017 arm64 is supported. Trying to set $MSVS_ARCH to an architecture that's not supported for a given Visual Studio version will generate an error.

MSVS_PROJECT_GUID
    The string placed in a generated Microsoft Visual C++ project file as the value of the ProjectGUID attribute. There is no default value. If not defined, a new GUID is generated.

MSVS_SCC_AUX_PATH
    The path name placed in a generated Microsoft Visual C++ project file as the value of the SccAuxPath attribute if the MSVS_SCC_PROVIDER construction variable is also set. There is no default value.

MSVS_SCC_CONNECTION_ROOT
    The root path of projects in your SCC workspace, i.e the path under which all project and solution files will be generated. It is used as a reference path from which the relative paths of the generated Microsoft Visual C++ project and solution files are computed. The relative project file path is placed as the value of the SccLocalPath attribute of the project file and as the values of the SccProjectFilePathRelativizedFromConnection[i] (where [i] ranges from 0 to the number of projects in the solution) attributes of the GlobalSection(SourceCodeControl) section of the Microsoft Visual Studio solution file. Similarly the relative solution file path is placed as the values of the SccLocalPath[i] (where [i] ranges from 0 to the number of projects in the solution) attributes of the GlobalSection(SourceCodeControl) section of the Microsoft Visual Studio solution file. This is used only if the MSVS_SCC_PROVIDER construction variable is also set. The default value is the current working directory.

MSVS_SCC_PROJECT_NAME
    The project name placed in a generated Microsoft Visual C++ project file as the value of the SccProjectName attribute if the MSVS_SCC_PROVIDER construction variable is also set. In this case the string is also placed in the SccProjectName0 attribute of the GlobalSection(SourceCodeControl) section of the Microsoft Visual Studio solution file. There is no default value.

MSVS_SCC_PROVIDER
    The string placed in a generated Microsoft Visual C++ project file as the value of the SccProvider attribute. The string is also placed in the SccProvider0 attribute of the GlobalSection(SourceCodeControl) section of the Microsoft Visual Studio solution file. There is no default value.

MSVS_VERSION
    Set the preferred version of Microsoft Visual Studio to use.

    If $MSVS_VERSION is not set, SCons will (by default) select the latest version of Visual Studio installed on your system. So, if you have version 6 and version 7 (MSVS .NET) installed, it will prefer version 7. You can override this by specifying the $MSVS_VERSION variable when initializing the Environment, setting it to the appropriate version ('6.0' or '7.0', for example). If the specified version isn't installed, tool initialization will fail.

    Deprecated since 1.3.0: $MSVS_VERSION is deprecated in favor of $MSVC_VERSION. As a transitional aid, if $MSVS_VERSION is set and $MSVC_VERSION is not, $MSVC_VERSION will be initialized to the value of $MSVS_VERSION. An error is raised if If both are set and have different values,

MSVSBUILDCOM
    The build command line placed in a generated Microsoft Visual C++ project file. The default is to have Visual Studio invoke SCons with any specified build targets.

MSVSCLEANCOM
    The clean command line placed in a generated Microsoft Visual C++ project file. The default is to have Visual Studio invoke SCons with the -c option to remove any specified targets.

MSVSENCODING
    The encoding string placed in a generated Microsoft Visual C++ project file. The default is encoding Windows-1252.

MSVSPROJECTCOM
    The action used to generate Microsoft Visual C++ project files.

MSVSPROJECTSUFFIX
    The suffix used for Microsoft Visual C++ project (DSP) files. The default value is .vcxproj when using Visual Studio 2010 and later, .vcproj when using Visual Studio versions between 2002 and 2008, and .dsp when using Visual Studio 6.0.

MSVSREBUILDCOM
    The rebuild command line placed in a generated Microsoft Visual C++ project file. The default is to have Visual Studio invoke SCons with any specified rebuild targets.

MSVSSCONS
    The SCons used in generated Microsoft Visual C++ project files. The default is the version of SCons being used to generate the project file.

MSVSSCONSCOM
    The default SCons command used in generated Microsoft Visual C++ project files.

MSVSSCONSCRIPT
    The sconscript file (that is, SConstruct or SConscript file) that will be invoked by Microsoft Visual C++ project files (through the $MSVSSCONSCOM variable). The default is the same sconscript file that contains the call to MSVSProject to build the project file.

MSVSSCONSFLAGS
    The SCons flags used in generated Microsoft Visual C++ project files.

MSVSSOLUTIONCOM
    The action used to generate Microsoft Visual Studio solution files.

MSVSSOLUTIONSUFFIX
    The suffix used for Microsoft Visual Studio solution (DSW) files. The default value is .sln when using Visual Studio version 7.x (.NET 2002) and later, and .dsw when using Visual Studio 6.0.

MT
    The program used on Windows systems to embed manifests into DLLs and EXEs. See also $WINDOWS_EMBED_MANIFEST.

MTEXECOM
    The Windows command line used to embed manifests into executables. See also $MTSHLIBCOM.

MTFLAGS
    Flags passed to the $MT manifest embedding program (Windows only).

MTSHLIBCOM
    The Windows command line used to embed manifests into shared libraries (DLLs). See also $MTEXECOM.

MWCW_VERSION
    The version number of the MetroWerks CodeWarrior C compiler to be used.

MWCW_VERSIONS
    A list of installed versions of the MetroWerks CodeWarrior C compiler on this system.

NAME
    Specfies the name of the project to package.

    See the Package builder.

NINJA_ALIAS_NAME
    The name of the alias target which will cause SCons to create the ninja build file, and then (optionally) run ninja. The default value is generate-ninja.

NINJA_CMD_ARGS
    A string which will pass arguments through SCons to the ninja command when scons executes ninja. Has no effect if $NINJA_DISABLE_AUTO_RUN is set.

    This value can also be passed on the command line:

        scons NINJA_CMD_ARGS=-v
        or
        scons NINJA_CMD_ARGS="-v -j 3"

NINJA_COMPDB_EXPAND
    Boolean value to instruct ninja to expand the command line arguments normally put into response files. If true, prevents unexpanded lines in the compilation database like “gcc @rsp_file” and instead yields expanded lines like “gcc -c -o myfile.o myfile.c -Ia -DXYZ”.

    Ninja's compdb tool added the -x flag in Ninja V1.9.0

NINJA_DEPFILE_PARSE_FORMAT
    Determines the type of format ninja should expect when parsing header include depfiles. Can be msvc, gcc, or clang. The msvc option corresponds to /showIncludes format, and gcc or clang correspond to -MMD -MF.

NINJA_DIR
    The builddir value. Propagates directly into the generated ninja build file. From Ninja's docs: “ A directory for some Ninja output files. ... (You can also store other build output in this directory.) ” The default value is .ninja.

NINJA_DISABLE_AUTO_RUN
    Boolean. Default: False. If true, SCons will not run ninja automatically after creating the ninja build file.

    If not explicitly set, this will be set to True if --disable_execute_ninja or SetOption('disable_execute_ninja', True) is seen.

NINJA_ENV_VAR_CACHE
    A string that sets the environment for any environment variables that differ between the OS environment and the SCons execution environment.

    It will be compatible with the default shell of the operating system.

    If not explicitly set, SCons will generate this dynamically from the execution environment stored in the current construction environment (e.g. env['ENV']) where those values differ from the existing shell..

NINJA_FILE_NAME
    The filename for the generated Ninja build file. The default is ninja.build.

NINJA_FORCE_SCONS_BUILD
    If true, causes the build nodes to callback to scons instead of using ninja to build them. This is intended to be passed to the environment on the builder invocation. It is useful if you have a build node which does something which is not easily translated into ninja.

NINJA_GENERATED_SOURCE_ALIAS_NAME
    A string matching the name of a user defined alias which represents a list of all generated sources. This will prevent the auto-detection of generated sources from $NINJA_GENERATED_SOURCE_SUFFIXES. Then all other source files will be made to depend on this in the ninja build file, forcing the generated sources to be built first.

NINJA_GENERATED_SOURCE_SUFFIXES
    The list of source file suffixes which are generated by SCons build steps. All source files which match these suffixes will be added to the _generated_sources alias in the output ninja build file. Then all other source files will be made to depend on this in the ninja build file, forcing the generated sources to be built first.

NINJA_MSVC_DEPS_PREFIX
    The msvc_deps_prefix string. Propagates directly into the generated ninja build file. From Ninja's docs: “defines the string which should be stripped from msvc's /showIncludes output”

NINJA_POOL
    Set the ninja_pool for this or all targets in scope for this env var.

NINJA_REGENERATE_DEPS
    A generator function used to create a ninja depfile which includes all the files which would require SCons to be invoked if they change. Or a list of said files.

_NINJA_REGENERATE_DEPS_FUNC
    Internal value used to specify the function to call with argument env to generate the list of files which if changed would require the ninja build file to be regenerated.

NINJA_SCONS_DAEMON_KEEP_ALIVE
    The number of seconds for the SCons deamon launched by ninja to stay alive. (Default: 180000)

NINJA_SCONS_DAEMON_PORT
    The TCP/IP port for the SCons daemon to listen on. NOTE: You cannot use a port already being listened to on your build machine. (Default: random number between 10000,60000)

NINJA_SYNTAX
    The path to a custom ninja_syntax.py file which is used in generation. The tool currently assumes you have ninja installed as a Python module and grabs the syntax file from that installation if $NINJA_SYNTAX is not explicitly set.

no_import_lib
    When set to non-zero, suppresses creation of a corresponding Windows static import lib by the SharedLibrary builder when used with MinGW, Microsoft Visual Studio or Metrowerks. This also suppresses creation of an export (.exp) file when using Microsoft Visual Studio.

OBJPREFIX
    The prefix used for (static) object file names.

OBJSUFFIX
    The suffix used for (static) object file names.

PACKAGEROOT
    Specifies the directory where all files in resulting archive will be placed if applicable. The default value is “$NAME-$VERSION”.

    See the Package builder.

PACKAGETYPE
    Selects the package type to build when using the Package builder. May be a string or list of strings. See the docuentation for the builder for the currently supported types.

    $PACKAGETYPE may be overridden with the --package-type command line option.

    See the Package builder.

PACKAGEVERSION
    The version of the package (not the underlying project). This is currently only used by the rpm packager and should reflect changes in the packaging, not the underlying project code itself.

    See the Package builder.

PCH
    A node for the Microsoft Visual C++ precompiled header that will be used when compiling object files. This variable is ignored by tools other than Microsoft Visual C++. When this variable is defined, SCons will add options to the compiler command line to cause it to use the precompiled header, and will also set up the dependencies for the PCH file. Examples:

        env['PCH'] = File('StdAfx.pch')
        env['PCH'] = env.PCH('pch.cc')[0]

PCHCOM
    The command line used by the PCH builder to generated a precompiled header.

PCHCOMSTR
    The string displayed when generating a precompiled header. If not set, then $PCHCOM (the command line) is displayed.

PCHPDBFLAGS
    A construction variable that, when expanded, adds the /yD flag to the command line only if the $PDB construction variable is set.

PCHSTOP
    This variable specifies how much of a source file is precompiled. This variable is ignored by tools other than Microsoft Visual C++, or when the PCH variable is not being used. When this variable is define it must be a string that is the name of the header that is included at the end of the precompiled portion of the source files, or the empty string if the "#pragma hrdstop" construct is being used:

        env['PCHSTOP'] = 'StdAfx.h'

PDB
    The Microsoft Visual C++ PDB file that will store debugging information for object files, shared libraries, and programs. This variable is ignored by tools other than Microsoft Visual C++. When this variable is defined SCons will add options to the compiler and linker command line to cause them to generate external debugging information, and will also set up the dependencies for the PDB file. Example:

        env['PDB'] = 'hello.pdb'

    The Microsoft Visual C++ compiler switch that SCons uses by default to generate PDB information is /Z7. This works correctly with parallel (-j) builds because it embeds the debug information in the intermediate object files, as opposed to sharing a single PDB file between multiple object files. This is also the only way to get debug information embedded into a static library. Using the /Zi instead may yield improved link-time performance, although parallel builds will no longer work. You can generate PDB files with the /Zi switch by overriding the default $CCPDBFLAGS variable; see the entry for that variable for specific examples.

PDFLATEX
    The pdflatex utility.

PDFLATEXCOM
    The command line used to call the pdflatex utility.

PDFLATEXCOMSTR
    The string displayed when calling the pdflatex utility. If this is not set, then $PDFLATEXCOM (the command line) is displayed.

        env = Environment(PDFLATEX;COMSTR = "Building $TARGET from LaTeX input $SOURCES")

PDFLATEXFLAGS
    General options passed to the pdflatex utility.

PDFPREFIX
    The prefix used for PDF file names.

PDFSUFFIX
    The suffix used for PDF file names.

PDFTEX
    The pdftex utility.

PDFTEXCOM
    The command line used to call the pdftex utility.

PDFTEXCOMSTR
    The string displayed when calling the pdftex utility. If this is not set, then $PDFTEXCOM (the command line) is displayed.

        env = Environment(PDFTEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

PDFTEXFLAGS
    General options passed to the pdftex utility.

PKGCHK
    On Solaris systems, the package-checking program that will be used (along with $PKGINFO) to look for installed versions of the Sun PRO C++ compiler. The default is /usr/sbin/pgkchk.

PKGINFO
    On Solaris systems, the package information program that will be used (along with $PKGCHK) to look for installed versions of the Sun PRO C++ compiler. The default is pkginfo.

PLATFORM
    The name of the platform used to create this construction environment. SCons sets this when initializing the platform, which by default is auto-detected (see the platform argument to Environment).

        env = Environment(tools=[])
        if env['PLATFORM'] == 'cygwin':
            Tool('mingw')(env)
        else:
            Tool('msvc')(env)

POAUTOINIT
    The $POAUTOINIT variable, if set to True (on non-zero numeric value), let the msginit tool to automatically initialize missing PO files with msginit(1). This applies to both, POInit and POUpdate builders (and others that use any of them).

POCREATE_ALIAS
    Common alias for all PO files created with POInit builder (default: 'po-create'). See msginit tool and POInit builder.

POSUFFIX
    Suffix used for PO files (default: '.po') See msginit tool and POInit builder.

POTDOMAIN
    The $POTDOMAIN defines default domain, used to generate POT filename as $POTDOMAIN.pot when no POT file name is provided by the user. This applies to POTUpdate, POInit and POUpdate builders (and builders, that use them, e.g. Translate). Normally (if $POTDOMAIN is not defined), the builders use messages.pot as default POT file name.

POTSUFFIX
    Suffix used for PO Template files (default: '.pot'). See xgettext tool and POTUpdate builder.

POTUPDATE_ALIAS
    Name of the common phony target for all PO Templates created with POUpdate (default: 'pot-update'). See xgettext tool and POTUpdate builder.

POUPDATE_ALIAS
    Common alias for all PO files being defined with POUpdate builder (default: 'po-update'). See msgmerge tool and POUpdate builder.

PRINT_CMD_LINE_FUNC
    A Python function used to print the command lines as they are executed (assuming command printing is not disabled by the -q or -s options or their equivalents). The function must accept four arguments: s, target, source and env. s is a string showing the command being executed, target, is the target being built (file node, list, or string name(s)), source, is the source(s) used (file node, list, or string name(s)), and env is the environment being used.

    The function must do the printing itself. The default implementation, used if this variable is not set or is None, is to just print the string, as in:

        def print_cmd_line(s, target, source, env):
            sys.stdout.write(s + "\n")

    Here is an example of a more interesting function:

        def print_cmd_line(s, target, source, env):
            sys.stdout.write(
                "Building %s -> %s...\n"
                % (
                    ' and '.join([str(x) for x in source]),
                    ' and '.join([str(x) for x in target]),
                )
            )
        env = Environment(PRINT_CMD_LINE_FUNC=print_cmd_line)
        env.Program('foo', ['foo.c', 'bar.c'])

    This prints:

        ...
        scons: Building targets ...
        Building bar.c -> bar.o...
        Building foo.c -> foo.o...
        Building foo.o and bar.o -> foo...
        scons: done building targets.

    Another example could be a function that logs the actual commands to a file.

PROGEMITTER
    Contains the emitter specification for the Program builder. The manpage section "Builder Objects" contains general information on specifying emitters.

PROGPREFIX
    The prefix used for executable file names.

PROGSUFFIX
    The suffix used for executable file names.

PSCOM
    The command line used to convert TeX DVI files into a PostScript file.

PSCOMSTR
    The string displayed when a TeX DVI file is converted into a PostScript file. If this is not set, then $PSCOM (the command line) is displayed.

PSPREFIX
    The prefix used for PostScript file names.

PSSUFFIX
    The prefix used for PostScript file names.

QT3_AUTOSCAN
    Turn off scanning for mocable files. Use the Moc Builder to explicitly specify files to run moc on.

    Changed in 4.5.0: renamed from QT_AUTOSCAN.

QT3_BINPATH
    The path where the Qt binaries are installed. The default value is '$QT3DIR/bin'.

    Changed in 4.5.0: renamed from QT_BINPATH.

QT3_CPPPATH
    The path where the Qt header files are installed. The default value is '$QT3DIR/include'. Note: If you set this variable to None, the tool won't change the $CPPPATH construction variable.

    Changed in 4.5.0: renamed from QT_CPPPATH.

QT3_DEBUG
    Prints lots of debugging information while scanning for moc files.

    Changed in 4.5.0: renamed from QT_DEBUG.

QT3_LIB
    Default value is 'qt'. You may want to set this to 'qt-mt'. Note: If you set this variable to None, the tool won't change the $LIBS variable.

    Changed in 4.5.0: renamed from QT_LIB.

QT3_LIBPATH
    The path where the Qt libraries are installed. The default value is '$QT3DIR/lib'. Note: If you set this variable to None, the tool won't change the $LIBPATH construction variable.

    Changed in 4.5.0: renamed from QT_LIBPATH.

QT3_MOC
    Default value is '$QT3_BINPATH/moc'.

QT3_MOCCXXPREFIX
    Default value is ''. Prefix for moc output files when source is a C++ file.

QT3_MOCCXXSUFFIX
    Default value is '.moc'. Suffix for moc output files when source is a C++ file.

    Changed in 4.5.0: renamed from QT_MOCCXXSUFFIX.

QT3_MOCFROMCXXCOM
    Command to generate a moc file from a C++ file.

    Changed in 4.5.0: renamed from QT_MOCFROMCXXCOM.

QT3_MOCFROMCXXCOMSTR
    The string displayed when generating a moc file from a C++ file. If this is not set, then $QT3_MOCFROMCXXCOM (the command line) is displayed.

    Changed in 4.5.0: renamed from QT_MOCFROMCXXCOMSTR.

QT3_MOCFROMCXXFLAGS
    Default value is '-i'. These flags are passed to moc when moccing a C++ file.

    Changed in 4.5.0: renamed from QT_MOCFROMCXXFLAGS.

QT3_MOCFROMHCOM
    Command to generate a moc file from a header.

    Changed in 4.5.0: renamed from QT_MOCFROMSHCOM.

QT3_MOCFROMHCOMSTR
    The string displayed when generating a moc file from a C++ file. If this is not set, then $QT3_MOCFROMHCOM (the command line) is displayed.

    Changed in 4.5.0: renamed from QT_MOCFROMSHCOMSTR.

QT3_MOCFROMHFLAGS
    Default value is ''. These flags are passed to moc when moccing a header file.

    Changed in 4.5.0: renamed from QT_MOCFROMSHFLAGS.

QT3_MOCHPREFIX
    Default value is 'moc_'. Prefix for moc output files when source is a header.

    Changed in 4.5.0: renamed from QT_MOCHPREFIX.

QT3_MOCHSUFFIX
    Default value is '$CXXFILESUFFIX'. Suffix for moc output files when source is a header.

    Changed in 4.5.0: renamed from QT_MOCHSUFFIX.

QT3_UIC
    Default value is '$QT3_BINPATH/uic'.

    Changed in 4.5.0: renamed from QT_UIC.

QT3_UICCOM
    Command to generate header files from .ui files.

    Changed in 4.5.0: renamed from QT_UICCOM.

QT3_UICCOMSTR
    The string displayed when generating header files from .ui files. If this is not set, then $QT3_UICCOM (the command line) is displayed.

    Changed in 4.5.0: renamed from QT_UICCOMSTR.

QT3_UICDECLFLAGS
    Default value is ''. These flags are passed to uic when creating a header file from a .ui file.

    Changed in 4.5.0: renamed from QT_UICDECLFLAGS.

QT3_UICDECLPREFIX
    Default value is ''. Prefix for uic generated header files.

    Changed in 4.5.0: renamed from QT_UICDECLPREFIX.

QT3_UICDECLSUFFIX
    Default value is '.h'. Suffix for uic generated header files.

    Changed in 4.5.0: renamed from QT_UICDECLSUFFIX.

QT3_UICIMPLFLAGS
    Default value is ''. These flags are passed to uic when creating a C++ file from a .ui file.

    Changed in 4.5.0: renamed from QT_UICIMPFLAGS.

QT3_UICIMPLPREFIX
    Default value is 'uic_'. Prefix for uic generated implementation files.

    Changed in 4.5.0: renamed from QT_UICIMPLPREFIX.

QT3_UICIMPLSUFFIX
    Default value is '$CXXFILESUFFIX'. Suffix for uic generated implementation files.

    Changed in 4.5.0: renamed from QT_UICIMPLSUFFIX.

QT3_UISUFFIX
    Default value is '.ui'. Suffix of designer input files.

    Changed in 4.5.0: renamed from QT_UISUFFIX.

QT3DIR
    The path to the Qt installation to build against. If not already set, qt3 tool tries to obtain this from os.environ; if not found there, it tries to make a guess.

    Changed in 4.5.0: renamed from QTDIR.

RANLIB
    The archive indexer.

RANLIBCOM
    The command line used to index a static library archive.

RANLIBCOMSTR
    The string displayed when a static library archive is indexed. If this is not set, then $RANLIBCOM (the command line) is displayed.

        env = Environment(RANLIBCOMSTR = "Indexing $TARGET")

RANLIBFLAGS
    General options passed to the archive indexer.

RC
    The resource compiler used to build a Microsoft Visual C++ resource file.

RCCOM
    The command line used to build a Microsoft Visual C++ resource file.

RCCOMSTR
    The string displayed when invoking the resource compiler to build a Microsoft Visual C++ resource file. If this is not set, then $RCCOM (the command line) is displayed.

RCFLAGS
    The flags passed to the resource compiler by the RES builder.

RCINCFLAGS
    An automatically-generated construction variable containing the command-line options for specifying directories to be searched by the resource compiler. The value of $RCINCFLAGS is created by respectively prepending and appending $RCINCPREFIX and $RCINCSUFFIX to the beginning and end of each directory in $CPPPATH.

RCINCPREFIX
    The prefix (flag) used to specify an include directory on the resource compiler command line. This will be prepended to the beginning of each directory in the $CPPPATH construction variable when the $RCINCFLAGS variable is expanded.

RCINCSUFFIX
    The suffix used to specify an include directory on the resource compiler command line. This will be appended to the end of each directory in the $CPPPATH construction variable when the $RCINCFLAGS variable is expanded.

RDirs
    A function that converts a string into a list of Dir instances by searching the repositories.

REGSVR
    The program used on Windows systems to register a newly-built DLL library whenever the SharedLibrary builder is passed a keyword argument of register=True.

REGSVRCOM
    The command line used on Windows systems to register a newly-built DLL library whenever the SharedLibrary builder is passed a keyword argument of register=True.

REGSVRCOMSTR
    The string displayed when registering a newly-built DLL file. If this is not set, then $REGSVRCOM (the command line) is displayed.

REGSVRFLAGS
    Flags passed to the DLL registration program on Windows systems when a newly-built DLL library is registered. By default, this includes the /s that prevents dialog boxes from popping up and requiring user attention.

RMIC
    The Java RMI stub compiler.

RMICCOM
    The command line used to compile stub and skeleton class files from Java classes that contain RMI implementations. Any options specified in the $RMICFLAGS construction variable are included on this command line.

RMICCOMSTR
    The string displayed when compiling stub and skeleton class files from Java classes that contain RMI implementations. If this is not set, then $RMICCOM (the command line) is displayed.

        env = Environment(
            RMICCOMSTR="Generating stub/skeleton class files $TARGETS from $SOURCES"
        )

RMICFLAGS
    General options passed to the Java RMI stub compiler.

RPATH
    A list of paths to search for shared libraries when running programs. Currently only used in the GNU (gnulink), IRIX (sgilink) and Sun (sunlink) linkers. Ignored on platforms and toolchains that don't support it. Note that the paths added to RPATH are not transformed by scons in any way: if you want an absolute path, you must make it absolute yourself.

_RPATH
    An automatically-generated construction variable containing the rpath flags to be used when linking a program with shared libraries. The value of $_RPATH is created by respectively prepending $RPATHPREFIX and appending $RPATHSUFFIX to the beginning and end of each directory in $RPATH.

RPATHPREFIX
    The prefix used to specify a directory to be searched for shared libraries when running programs. This will be prepended to the beginning of each directory in the $RPATH construction variable when the $_RPATH variable is automatically generated.

RPATHSUFFIX
    The suffix used to specify a directory to be searched for shared libraries when running programs. This will be appended to the end of each directory in the $RPATH construction variable when the $_RPATH variable is automatically generated.

RPCGEN
    The RPC protocol compiler.

RPCGENCLIENTFLAGS
    Options passed to the RPC protocol compiler when generating client side stubs. These are in addition to any flags specified in the $RPCGENFLAGS construction variable.

RPCGENFLAGS
    General options passed to the RPC protocol compiler.

RPCGENHEADERFLAGS
    Options passed to the RPC protocol compiler when generating a header file. These are in addition to any flags specified in the $RPCGENFLAGS construction variable.

RPCGENSERVICEFLAGS
    Options passed to the RPC protocol compiler when generating server side stubs. These are in addition to any flags specified in the $RPCGENFLAGS construction variable.

RPCGENXDRFLAGS
    Options passed to the RPC protocol compiler when generating XDR routines. These are in addition to any flags specified in the $RPCGENFLAGS construction variable.

SCANNERS
    A list of the available implicit dependency scanners. New file scanners may be added by appending to this list, although the more flexible approach is to associate scanners with a specific Builder. See the manpage sections "Builder Objects" and "Scanner Objects" for more information.

SCONS_HOME
    The (optional) path to the SCons library directory, initialized from the external environment. If set, this is used to construct a shorter and more efficient search path in the $MSVSSCONS command line executed from C++ project files.

SHCC
    The C compiler used for generating shared-library objects. See also $CC for compiling to static objects.

SHCCCOM
    The command line used to compile a C source file to a shared-library object file. Any options specified in the $SHCFLAGS, $SHCCFLAGS and $CPPFLAGS construction variables are included on this command line. See also $CCCOM for compiling to static objects.

SHCCCOMSTR
    If set, the string displayed when a C source file is compiled to a shared object file. If not set, then $SHCCCOM (the command line) is displayed. See also $CCCOMSTR for compiling to static objects.

        env = Environment(SHCCCOMSTR = "Compiling shared object $TARGET")

SHCCFLAGS
    Options that are passed to the C and C++ compilers to generate shared-library objects. See also $CCFLAGS for compiling to static objects.

SHCFLAGS
    Options that are passed to the C compiler (only; not C++) to generate shared-library objects. See also $CFLAGS for compiling to static objects.

SHCXX
    The C++ compiler used for generating shared-library objects. See also $CXX for compiling to static objects.

SHCXXCOM
    The command line used to compile a C++ source file to a shared-library object file. Any options specified in the $SHCXXFLAGS and $CPPFLAGS construction variables are included on this command line. See also $CXXCOM for compiling to static objects.

SHCXXCOMSTR
    If set, the string displayed when a C++ source file is compiled to a shared object file. If not set, then $SHCXXCOM (the command line) is displayed. See also $CXXCOMSTR for compiling to static objects.

        env = Environment(SHCXXCOMSTR = "Compiling shared object $TARGET")

SHCXXFLAGS
    Options that are passed to the C++ compiler to generate shared-library objects. See also $CXXFLAGS for compiling to static objects.

SHDC
    The name of the compiler to use when compiling D source destined to be in a shared objects. See also $DC for compiling to static objects.

SHDCOM
    The command line to use when compiling code to be part of shared objects. See also $DCOM for compiling to static objects.

SHDCOMSTR
    If set, the string displayed when a D source file is compiled to a (shared) object file. If not set, then $SHDCOM (the command line) is displayed. See also $DCOMSTR for compiling to static objects.

SHDLIBVERSIONFLAGS
    Extra flags added to $SHDLINKCOM when building versioned SharedLibrary. These flags are only used when $SHLIBVERSION is set.

SHDLINK
    The linker to use when creating shared objects for code bases include D sources. See also $DLINK for linking static objects.

SHDLINKCOM
    The command line to use when generating shared objects. See also $DLINKCOM for linking static objects.

SHDLINKFLAGS
    The list of flags to use when generating a shared object. See also $DLINKFLAGS for linking static objects.

SHELL
    A string naming the shell program that will be passed to the $SPAWN function. See the $SPAWN construction variable for more information.

SHELL_ENV_GENERATORS
    A hook allowing the execution environment to be modified prior to the actual execution of a command line from an action via the spawner function defined by $SPAWN. Allows substitution based on targets and sources, as well as values from the construction environment, adding extra environment variables, etc.

    The value must be a list (or other iterable) of functions which each generate or alter the execution environment dictionary. The first function will be passed a copy of the initial execution environment ($ENV in the current construction environment); the dictionary returned by that function is passed to the next, until the iterable is exhausted and the result returned for use by the command spawner. The original execution environment is not modified.

    Each function provided in $SHELL_ENV_GENERATORS must accept four arguments and return a dictionary: env is the construction environment for this action; target is the list of targets associated with this action; source is the list of sources associated with this action; and shell_env is the current dictionary after iterating any previous $SHELL_ENV_GENERATORS functions (this can be compared to the original execution environment, which is available as env['ENV'], to detect any changes).

    Example:

        def custom_shell_env(env, target, source, shell_env):
            """customize shell_env if desired"""
            if str(target[0]) == 'special_target':
                shell_env['SPECIAL_VAR'] = env.subst('SOME_VAR', target=target, source=source)
            return shell_env
        env["SHELL_ENV_GENERATORS"] = [custom_shell_env]

    Available since 4.4

SHF03
    The Fortran 03 compiler used for generating shared-library objects. You should normally set the $SHFORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $SHF03 if you need to use a specific compiler or compiler version for Fortran 03 files.

SHF03COM
    The command line used to compile a Fortran 03 source file to a shared-library object file. You only need to set $SHF03COM if you need to use a specific command line for Fortran 03 files. You should normally set the $SHFORTRANCOM variable, which specifies the default command line for all Fortran versions.

SHF03COMSTR
    If set, the string displayed when a Fortran 03 source file is compiled to a shared-library object file. If not set, then $SHF03COM or $SHFORTRANCOM (the command line) is displayed.

SHF03FLAGS
    Options that are passed to the Fortran 03 compiler to generated shared-library objects. You only need to set $SHF03FLAGS if you need to define specific user options for Fortran 03 files. You should normally set the $FORTRANCOMMONFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

SHF03PPCOM
    The command line used to compile a Fortran 03 source file to a shared-library object file after first running the file through the C preprocessor. Any options specified in the $SHF03FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $SHF03PPCOM if you need to use a specific C-preprocessor command line for Fortran 03 files. You should normally set the $SHFORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

SHF03PPCOMSTR
    If set, the string displayed when a Fortran 03 source file is compiled to a shared-library object file after first running the file through the C preprocessor. If not set, then $SHF03PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

SHF08
    The Fortran 08 compiler used for generating shared-library objects. You should normally set the $SHFORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $SHF08 if you need to use a specific compiler or compiler version for Fortran 08 files.

SHF08COM
    The command line used to compile a Fortran 08 source file to a shared-library object file. You only need to set $SHF08COM if you need to use a specific command line for Fortran 08 files. You should normally set the $SHFORTRANCOM variable, which specifies the default command line for all Fortran versions.

SHF08COMSTR
    If set, the string displayed when a Fortran 08 source file is compiled to a shared-library object file. If not set, then $SHF08COM or $SHFORTRANCOM (the command line) is displayed.

SHF08FLAGS
    Options that are passed to the Fortran 08 compiler to generated shared-library objects. You only need to set $SHF08FLAGS if you need to define specific user options for Fortran 08 files. You should normally set the $FORTRANCOMMONFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

SHF08PPCOM
    The command line used to compile a Fortran 08 source file to a shared-library object file after first running the file through the C preprocessor. Any options specified in the $SHF08FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $SHF08PPCOM if you need to use a specific C-preprocessor command line for Fortran 08 files. You should normally set the $SHFORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

SHF08PPCOMSTR
    If set, the string displayed when a Fortran 08 source file is compiled to a shared-library object file after first running the file through the C preprocessor. If not set, then $SHF08PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

SHF77
    The Fortran 77 compiler used for generating shared-library objects. You should normally set the $SHFORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $SHF77 if you need to use a specific compiler or compiler version for Fortran 77 files.

SHF77COM
    The command line used to compile a Fortran 77 source file to a shared-library object file. You only need to set $SHF77COM if you need to use a specific command line for Fortran 77 files. You should normally set the $SHFORTRANCOM variable, which specifies the default command line for all Fortran versions.

SHF77COMSTR
    If set, the string displayed when a Fortran 77 source file is compiled to a shared-library object file. If not set, then $SHF77COM or $SHFORTRANCOM (the command line) is displayed.

SHF77FLAGS
    Options that are passed to the Fortran 77 compiler to generated shared-library objects. You only need to set $SHF77FLAGS if you need to define specific user options for Fortran 77 files. You should normally set the $FORTRANCOMMONFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

SHF77PPCOM
    The command line used to compile a Fortran 77 source file to a shared-library object file after first running the file through the C preprocessor. Any options specified in the $SHF77FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $SHF77PPCOM if you need to use a specific C-preprocessor command line for Fortran 77 files. You should normally set the $SHFORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

SHF77PPCOMSTR
    If set, the string displayed when a Fortran 77 source file is compiled to a shared-library object file after first running the file through the C preprocessor. If not set, then $SHF77PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

SHF90
    The Fortran 90 compiler used for generating shared-library objects. You should normally set the $SHFORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $SHF90 if you need to use a specific compiler or compiler version for Fortran 90 files.

SHF90COM
    The command line used to compile a Fortran 90 source file to a shared-library object file. You only need to set $SHF90COM if you need to use a specific command line for Fortran 90 files. You should normally set the $SHFORTRANCOM variable, which specifies the default command line for all Fortran versions.

SHF90COMSTR
    If set, the string displayed when a Fortran 90 source file is compiled to a shared-library object file. If not set, then $SHF90COM or $SHFORTRANCOM (the command line) is displayed.

SHF90FLAGS
    Options that are passed to the Fortran 90 compiler to generated shared-library objects. You only need to set $SHF90FLAGS if you need to define specific user options for Fortran 90 files. You should normally set the $FORTRANCOMMONFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

SHF90PPCOM
    The command line used to compile a Fortran 90 source file to a shared-library object file after first running the file through the C preprocessor. Any options specified in the $SHF90FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $SHF90PPCOM if you need to use a specific C-preprocessor command line for Fortran 90 files. You should normally set the $SHFORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

SHF90PPCOMSTR
    If set, the string displayed when a Fortran 90 source file is compiled to a shared-library object file after first running the file through the C preprocessor. If not set, then $SHF90PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

SHF95
    The Fortran 95 compiler used for generating shared-library objects. You should normally set the $SHFORTRAN variable, which specifies the default Fortran compiler for all Fortran versions. You only need to set $SHF95 if you need to use a specific compiler or compiler version for Fortran 95 files.

SHF95COM
    The command line used to compile a Fortran 95 source file to a shared-library object file. You only need to set $SHF95COM if you need to use a specific command line for Fortran 95 files. You should normally set the $SHFORTRANCOM variable, which specifies the default command line for all Fortran versions.

SHF95COMSTR
    If set, the string displayed when a Fortran 95 source file is compiled to a shared-library object file. If not set, then $SHF95COM or $SHFORTRANCOM (the command line) is displayed.

SHF95FLAGS
    Options that are passed to the Fortran 95 compiler to generated shared-library objects. You only need to set $SHF95FLAGS if you need to define specific user options for Fortran 95 files. You should normally set the $FORTRANCOMMONFLAGS variable, which specifies the user-specified options passed to the default Fortran compiler for all Fortran versions.

SHF95PPCOM
    The command line used to compile a Fortran 95 source file to a shared-library object file after first running the file through the C preprocessor. Any options specified in the $SHF95FLAGS and $CPPFLAGS construction variables are included on this command line. You only need to set $SHF95PPCOM if you need to use a specific C-preprocessor command line for Fortran 95 files. You should normally set the $SHFORTRANPPCOM variable, which specifies the default C-preprocessor command line for all Fortran versions.

SHF95PPCOMSTR
    If set, the string displayed when a Fortran 95 source file is compiled to a shared-library object file after first running the file through the C preprocessor. If not set, then $SHF95PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

SHFORTRAN
    The default Fortran compiler used for generating shared-library objects.

SHFORTRANCOM
    The command line used to compile a Fortran source file to a shared-library object file. By default, any options specified in the $SHFORTRANFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS construction variables are included on this command line. See also $FORTRANCOM.

SHFORTRANCOMSTR
    If set, the string displayed when a Fortran source file is compiled to a shared-library object file. If not set, then $SHFORTRANCOM (the command line) is displayed.

SHFORTRANFLAGS
    Options that are passed to the Fortran compiler to generate shared-library objects.

SHFORTRANPPCOM
    The command line used to compile a Fortran source file to a shared-library object file after first running the file through the C preprocessor. By default, any options specified in the $SHFORTRANFLAGS, $CPPFLAGS, $_CPPDEFFLAGS, $_FORTRANMODFLAG, and $_FORTRANINCFLAGS construction variables are included on this command line. See also $SHFORTRANCOM.

SHFORTRANPPCOMSTR
    If set, the string displayed when a Fortran source file is compiled to a shared-library object file after first running the file through the C preprocessor. If not set, then $SHFORTRANPPCOM (the command line) is displayed.

SHLIBEMITTER
    Contains the emitter specification for the SharedLibrary builder. The manpage section "Builder Objects" contains general information on specifying emitters.

SHLIBNOVERSIONSYMLINKS
    Instructs the SharedLibrary builder to not create symlinks for versioned shared libraries.

SHLIBPREFIX
    The prefix used for shared library file names.

_SHLIBSONAME
    A macro that automatically generates shared library's SONAME based on $TARGET, $SHLIBVERSION and $SHLIBSUFFIX. Used by SharedLibrary builder when the linker tool supports SONAME (e.g. gnulink).

SHLIBSUFFIX
    The suffix used for shared library file names.

SHLIBVERSION
    When this construction variable is defined, a versioned shared library is created by the SharedLibrary builder. This activates the $_SHLIBVERSIONFLAGS and thus modifies the $SHLINKCOM as required, adds the version number to the library name, and creates the symlinks that are needed. $SHLIBVERSION versions should exist as alpha-numeric, decimal-delimited values as defined by the regular expression "\w+[\.\w+]*". Example $SHLIBVERSION values include '1', '1.2.3', and '1.2.gitaa412c8b'.

_SHLIBVERSIONFLAGS
    This macro automatically introduces extra flags to $SHLINKCOM when building versioned SharedLibrary (that is when $SHLIBVERSION is set). _SHLIBVERSIONFLAGS usually adds $SHLIBVERSIONFLAGS and some extra dynamically generated options (such as -Wl,-soname=$_SHLIBSONAME. It is unused by "plain" (unversioned) shared libraries.

SHLIBVERSIONFLAGS
    Extra flags added to $SHLINKCOM when building versioned SharedLibrary. These flags are only used when $SHLIBVERSION is set.

SHLINK
    The linker for programs that use shared libraries. See also $LINK for linking static objects.

    On POSIX systems (those using the link tool), you should normally not change this value as it defaults to a "smart" linker tool which selects a compiler driver matching the type of source files in use. So for example, if you set $SHCXX to a specific compiler name, and are compiling C++ sources, the smartlink function will automatically select the same compiler for linking.

SHLINKCOM
    The command line used to link programs using shared libraries. See also $LINKCOM for linking static objects.

SHLINKCOMSTR
    The string displayed when programs using shared libraries are linked. If this is not set, then $SHLINKCOM (the command line) is displayed. See also $LINKCOMSTR for linking static objects.

        env = Environment(SHLINKCOMSTR = "Linking shared $TARGET")

SHLINKFLAGS
    General user options passed to the linker for programs using shared libraries. Note that this variable should not contain -l (or similar) options for linking with the libraries listed in $LIBS, nor -L (or similar) include search path options that scons generates automatically from $LIBPATH. See $_LIBFLAGS above, for the variable that expands to library-link options, and $_LIBDIRFLAGS above, for the variable that expands to library search path options. See also $LINKFLAGS for linking static objects.

SHOBJPREFIX
    The prefix used for shared object file names.

SHOBJSUFFIX
    The suffix used for shared object file names.

SONAME
    Variable used to hard-code SONAME for versioned shared library/loadable module.

        env.SharedLibrary('test', 'test.c', SHLIBVERSION='0.1.2', SONAME='libtest.so.2')

    The variable is used, for example, by gnulink linker tool.

SOURCE
    A reserved variable name that may not be set or used in a construction environment. (See the manpage section "Variable Substitution" for more information).

SOURCE_URL
    The URL (web address) of the location from which the project was retrieved. This is used to fill in the Source: field in the controlling information for Ipkg and RPM packages.

    See the Package builder.

SOURCES
    A reserved variable name that may not be set or used in a construction environment. (See the manpage section "Variable Substitution" for more information).

SOVERSION
    This will construct the SONAME using on the base library name (test in the example below) and use specified SOVERSION to create SONAME.

        env.SharedLibrary('test', 'test.c', SHLIBVERSION='0.1.2', SOVERSION='2')

    The variable is used, for example, by gnulink linker tool.

    In the example above SONAME would be libtest.so.2 which would be a symlink and point to libtest.so.0.1.2

SPAWN
    A command interpreter function that will be called to execute command line strings. The function must accept five arguments:

        def spawn(shell, escape, cmd, args, env):

    shell is a string naming the shell program to use, escape is a function that can be called to escape shell special characters in the command line, cmd is the path to the command to be executed, args holds the arguments to the command and env is a dictionary of environment variables defining the execution environment in which the command should be executed.

STATIC_AND_SHARED_OBJECTS_ARE_THE_SAME
    When this variable is true, static objects and shared objects are assumed to be the same; that is, SCons does not check for linking static objects into a shared library.

SUBST_DICT
    The dictionary used by the Substfile or Textfile builders for substitution values. It can be anything acceptable to the dict() constructor, so in addition to a dictionary, lists of tuples are also acceptable.

SUBSTFILEPREFIX
    The prefix used for Substfile file names, an empty string by default.

SUBSTFILESUFFIX
    The suffix used for Substfile file names, an empty string by default.

SUMMARY
    A short summary of what the project is about. This is used to fill in the Summary: field in the controlling information for Ipkg and RPM packages, and as the Description: field in MSI packages.

    See the Package builder.

SWIG
    The name of the SWIG compiler to use.

SWIGCFILESUFFIX
    The suffix that will be used for intermediate C source files generated by SWIG. The default value is '_wrap$CFILESUFFIX' - that is, the concatenation of the string _wrap and the current C suffix $CFILESUFFIX. By default, this value is used whenever the -c++ option is not specified as part of the $SWIGFLAGS construction variable.

SWIGCOM
    The command line used to call SWIG.

SWIGCOMSTR
    The string displayed when calling SWIG. If this is not set, then $SWIGCOM (the command line) is displayed.

SWIGCXXFILESUFFIX
    The suffix that will be used for intermediate C++ source files generated by SWIG. The default value is '_wrap$CXXFILESUFFIX' - that is, the concatenation of the string _wrap and the current C++ suffix $CXXFILESUFFIX. By default, this value is used whenever the -c++ option is specified as part of the $SWIGFLAGS construction variable.

SWIGDIRECTORSUFFIX
    The suffix that will be used for intermediate C++ header files generated by SWIG. These are only generated for C++ code when the SWIG 'directors' feature is turned on. The default value is _wrap.h.

SWIGFLAGS
    General options passed to SWIG. This is where you should set the target language (-python, -perl5, -tcl, etc.) and whatever other options you want to specify to SWIG, such as the -c++ to generate C++ code instead of C Code.

_SWIGINCFLAGS
    An automatically-generated construction variable containing the SWIG command-line options for specifying directories to be searched for included files. The value of $_SWIGINCFLAGS is created by respectively prepending and appending $SWIGINCPREFIX and $SWIGINCSUFFIX to the beginning and end of each directory in $SWIGPATH.

SWIGINCPREFIX
    The prefix used to specify an include directory on the SWIG command line. This will be prepended to the beginning of each directory in the $SWIGPATH construction variable when the $_SWIGINCFLAGS variable is automatically generated.

SWIGINCSUFFIX
    The suffix used to specify an include directory on the SWIG command line. This will be appended to the end of each directory in the $SWIGPATH construction variable when the $_SWIGINCFLAGS variable is automatically generated.

SWIGOUTDIR
    Specifies the output directory in which SWIG should place generated language-specific files. This will be used by SCons to identify the files that will be generated by the SWIG call, and translated into the swig -outdir option on the command line.

SWIGPATH
    The list of directories that SWIG will search for included files. SCons' SWIG implicit dependency scanner will search these directories for include files. The default value is an empty list.

    Don't explicitly put include directory arguments in $SWIGFLAGS the result will be non-portable and the directories will not be searched by the dependency scanner. Note: directory names in $SWIGPATH will be looked-up relative to the SConscript directory when they are used in a command. To force scons to look-up a directory relative to the root of the source tree use a top-relative path (#):

        env = Environment(SWIGPATH='#/include')

    The directory look-up can also be forced using the Dir() function:

        include = Dir('include')
        env = Environment(SWIGPATH=include)

    The directory list will be added to command lines through the automatically-generated $_SWIGINCFLAGS construction variable, which is constructed by respectively prepending and appending the values of the $SWIGINCPREFIX and $SWIGINCSUFFIX construction variables to the beginning and end of each directory in $SWIGPATH. Any command lines you define that need the SWIGPATH directory list should include $_SWIGINCFLAGS:

        env = Environment(SWIGCOM="my_swig -o $TARGET $_SWIGINCFLAGS $SOURCES")

SWIGVERSION
    The detected version string of the SWIG tool.

TAR
    The tar archiver.

TARCOM
    The command line used to call the tar archiver.

TARCOMSTR
    The string displayed when archiving files using the tar archiver. If this is not set, then $TARCOM (the command line) is displayed.

        env = Environment(TARCOMSTR = "Archiving $TARGET")

TARFLAGS
    General options passed to the tar archiver.

TARGET
    A reserved variable name that may not be set or used in a construction environment. (See the manpage section "Variable Substitution" for more information).

TARGET_ARCH
    The name of the hardware architecture that objects created using this construction environment should target. Can be set when creating a construction environment by passing as a keyword argument in the Environment call.

    On the win32 platform, if the Microsoft Visual C++ compiler is available, msvc tool setup is done using $HOST_ARCH and $TARGET_ARCH. If a value is not specified, will be set to the same value as $HOST_ARCH. Changing the value after the environment is initialized will not cause the tool to be reinitialized. Compiled objects will be in the target architecture if the compilation system supports generating for that target. The latest compiler which can fulfill the requirement will be selected, unless a different version is directed by the value of the $MSVC_VERSION construction variable.

    On the win32/msvc combination, valid target arch values are x86, arm, i386 for 32-bit targets and amd64, arm64, x86_64 and ia64 (Itanium) for 64-bit targets. For example, if you want to compile 64-bit binaries, you would set TARGET_ARCH='x86_64' when creating the construction environment. Note that not all target architectures are supported for all Visual Studio / MSVC versions. Check the relevant Microsoft documentation.

    $TARGET_ARCH is not currently used by other compilation tools, but the option is reserved to do so in future

TARGET_OS
    The name of the operating system that objects created using this construction environment should target. Can be set when creating a construction environment by passing as a keyword argument in the Environment call;.

    $TARGET_OS is not currently used by SCons but the option is reserved to do so in future

TARGETS
    A reserved variable name that may not be set or used in a construction environment. (See the manpage section "Variable Substitution" for more information).

TARSUFFIX
    The suffix used for tar file names.

TEMPFILE
    A callable object used to handle overly long command line strings, since operations which call out to a shell will fail if the line is longer than the shell can accept. This tends to particularly impact linking. The tempfile object stores the command line in a temporary file in the appropriate format, and returns an alternate command line so the invoked tool will make use of the contents of the temporary file. If you need to replace the default tempfile object, the callable should take into account the settings of $MAXLINELENGTH, $TEMPFILEPREFIX, $TEMPFILESUFFIX, $TEMPFILEARGJOIN, $TEMPFILEDIR and $TEMPFILEARGESCFUNC.

TEMPFILEARGESCFUNC
    The default argument escape function is SCons.Subst.quote_spaces. If you need to apply extra operations on a command argument (to fix Windows slashes, normalize paths, etc.) before writing to the temporary file, you can set the $TEMPFILEARGESCFUNC variable to a custom function. Such a function takes a single string argument and returns a new string with any modifications applied. Example:

        import sys
        import re
        from SCons.Subst import quote_spaces
        WINPATHSEP_RE = re.compile(r"\\([^\"'\\]|$)")
        def tempfile_arg_esc_func(arg):
            arg = quote_spaces(arg)
            if sys.platform != "win32":
                return arg
            # GCC requires double Windows slashes, let's use UNIX separator
            return WINPATHSEP_RE.sub(r"/\1", arg)
        env["TEMPFILEARGESCFUNC"] = tempfile_arg_esc_func

TEMPFILEARGJOIN
    The string to use to join the arguments passed to $TEMPFILE when the command line exceeds the limit set by $MAXLINELENGTH. The default value is a space. However for MSVC, MSLINK the default is a line separator as defined by os.linesep. Note this value is used literally and not expanded by the subst logic.

TEMPFILEDIR
    The directory to create the long-lines temporary file in.

TEMPFILEPREFIX
    The prefix for the name of the temporary file used to store command lines exceeding $MAXLINELENGTH. The default prefix is '@', which works for the Microsoft Visual C++ and GNU toolchains on Windows. Set this appropriately for other toolchains, for example '-@' for the diab compiler or '-via' for ARM toolchain.

TEMPFILESUFFIX
    The suffix for the name of the temporary file used to store command lines exceeding $MAXLINELENGTH. The suffix should include the dot ('.') if one is wanted as it will not be added automatically. The default is .lnk.

TEX
    The TeX formatter and typesetter.

TEXCOM
    The command line used to call the TeX formatter and typesetter.

TEXCOMSTR
    The string displayed when calling the TeX formatter and typesetter. If this is not set, then $TEXCOM (the command line) is displayed.

        env = Environment(TEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

TEXFLAGS
    General options passed to the TeX formatter and typesetter.

TEXINPUTS
    List of directories that the LaTeX program will search for include directories. The LaTeX implicit dependency scanner will search these directories for \include and \import files.

TEXTFILEPREFIX
    The prefix used for Textfile file names, an empty string by default.

TEXTFILESUFFIX
    The suffix used for Textfile file names; .txt by default.

TOOLS
    A list of the names of the Tool specification modules that were actually initialized in the current construction environment. This may be useful as a diagnostic aid to see if a tool did (or did not) run. The value is informative and is not guaranteed to be complete.

UNCHANGED_SOURCES
    A reserved variable name that may not be set or used in a construction environment. (See the manpage section "Variable Substitution" for more information).

UNCHANGED_TARGETS
    A reserved variable name that may not be set or used in a construction environment. (See the manpage section "Variable Substitution" for more information).

VENDOR
    The person or organization who supply the packaged software. This is used to fill in the Vendor: field in the controlling information for RPM packages, and the Manufacturer: field in the controlling information for MSI packages.

    See the Package builder.

VERSION
    The version of the project, specified as a string.

    See the Package builder.

VSWHERE
    Specify the location of vswhere.exe.

    The vswhere.exe executable is distributed with Microsoft Visual Studio and Build Tools since the 2017 edition, but is also available as a standalone installation. It allows queries to obtain detailed information about installations of 2017 and later editions. SCons makes use of this information to determine the state of compiler support for those editions.

    Setting the $VSWHERE variable to the path to a specific vswhere.exe binary causes SCons to use that binary. If not set, SCons will search for one, looking in the following locations in order, using the first found ($VSWHERE is updated with the location):
        %ProgramFiles(x86)%\Microsoft Visual Studio\Installer
        %ProgramFiles%\Microsoft Visual Studio\Installer
        %ChocolateyInstall%\bin
        %LOCALAPPDATA%\Microsoft\WinGet\Links
        %USERPROFILE%\scoop\shims
        %SCOOP%\shims

        Note
        In order to take effect, $VSWHERE must be set before the initial Microsoft Visual C++ compiler discovery takes place. Discovery happens, at the latest, during the first call to the Environment function, unless a tools list is specified which excludes the entire Microsoft Visual C++ toolchain - that is, omits "defaults" and any specific tool module that refers to parts of the toolchain (msvc, mslink, masm, midl and msvs). In this case, detection is deferred until any one of those tool modules is invoked manually. The following two examples illustrate this:

            # VSWHERE set as Environment is created
            env = Environment(VSWHERE='c:/my/path/to/vswhere')
            # Initialization deferred with empty tools, triggered manually
            env = Environment(tools=[])
            env['VSWHERE'] = r'c:/my/vswhere/install/location/vswhere.exe'
            env.Tool('msvc')
            env.Tool('mslink')
            env.Tool('msvs')

WINDOWS_EMBED_MANIFEST
    Set to True to embed the compiler-generated manifest (normally ${TARGET}.manifest) into all Windows executables and DLLs built with this environment, as a resource during their link step. This is done using $MT and $MTEXECOM and $MTSHLIBCOM. See also $WINDOWS_INSERT_MANIFEST.

WINDOWS_INSERT_DEF
    If set to true, a library build of a Windows shared library (.dll file) will include a reference to the corresponding module-definition file at the same time, if a module-definition file is not already listed as a build target. The name of the module-definition file will be constructed from the base name of the library and the construction variables $WINDOWSDEFSUFFIX and $WINDOWSDEFPREFIX. The default is to not add a module-definition file. The module-definition file is not created by this directive, and must be supplied by the developer.

WINDOWS_INSERT_MANIFEST
    If set to true, scons will add the manifest file generated by Microsoft Visual C++ 8.0 and later to the target list so SCons will be aware they were generated. In the case of an executable, the manifest file name is constructed using $WINDOWSPROGMANIFESTSUFFIX and $WINDOWSPROGMANIFESTPREFIX. In the case of a shared library, the manifest file name is constructed using $WINDOWSSHLIBMANIFESTSUFFIX and $WINDOWSSHLIBMANIFESTPREFIX. See also $WINDOWS_EMBED_MANIFEST.

WINDOWSDEFPREFIX
    The prefix used for a Windows linker module-definition file name. Defaults to empty.

WINDOWSDEFSUFFIX
    The suffix used for a Windows linker module-definition file name. Defaults to .def.

WINDOWSEXPPREFIX
    The prefix used for Windows linker exports file names. Defaults to empty.

WINDOWSEXPSUFFIX
    The suffix used for Windows linker exports file names. Defaults to .exp.

WINDOWSPROGMANIFESTPREFIX
    The prefix used for executable program manifest files generated by Microsoft Visual C++. Defaults to empty.

WINDOWSPROGMANIFESTSUFFIX
    The suffix used for executable program manifest files generated by Microsoft Visual C++. Defaults to .manifest.

WINDOWSSHLIBMANIFESTPREFIX
    The prefix used for shared library manifest files generated by Microsoft Visual C++. Defaults to empty.

WINDOWSSHLIBMANIFESTSUFFIX
    The suffix used for shared library manifest files generated by Microsoft Visual C++. Defaults to .manifest.

X_IPK_DEPENDS
    This is used to fill in the Depends: field in the controlling information for Ipkg packages.

    See the Package builder.

X_IPK_DESCRIPTION
    This is used to fill in the Description: field in the controlling information for Ipkg packages. The default value is “$SUMMARY\n$DESCRIPTION”

X_IPK_MAINTAINER
    This is used to fill in the Maintainer: field in the controlling information for Ipkg packages.

X_IPK_PRIORITY
    This is used to fill in the Priority: field in the controlling information for Ipkg packages.

X_IPK_SECTION
    This is used to fill in the Section: field in the controlling information for Ipkg packages.

X_MSI_LANGUAGE
    This is used to fill in the Language: attribute in the controlling information for MSI packages.

    See the Package builder.

X_MSI_LICENSE_TEXT
    The text of the software license in RTF format. Carriage return characters will be replaced with the RTF equivalent \\par.

    See the Package builder.

X_MSI_UPGRADE_CODE
    TODO

X_RPM_AUTOREQPROV
    This is used to fill in the AutoReqProv: field in the RPM .spec file.

    See the Package builder.

X_RPM_BUILD
    internal, but overridable

X_RPM_BUILDREQUIRES
    This is used to fill in the BuildRequires: field in the RPM .spec file. Note this should only be used on a host managed by rpm as the dependencies will not be resolvable at build time otherwise.

X_RPM_BUILDROOT
    internal, but overridable

X_RPM_CLEAN
    internal, but overridable

X_RPM_CONFLICTS
    This is used to fill in the Conflicts: field in the RPM .spec file.

X_RPM_DEFATTR
    This value is used as the default attributes for the files in the RPM package. The default value is “(-,root,root)”.

X_RPM_DISTRIBUTION
    This is used to fill in the Distribution: field in the RPM .spec file.

X_RPM_EPOCH
    This is used to fill in the Epoch: field in the RPM .spec file.

X_RPM_EXCLUDEARCH
    This is used to fill in the ExcludeArch: field in the RPM .spec file.

X_RPM_EXLUSIVEARCH
    This is used to fill in the ExclusiveArch: field in the RPM .spec file.

X_RPM_EXTRADEFS
    A list used to supply extra defintions or flags to be added to the RPM .spec file. Each item is added as-is with a carriage return appended. This is useful if some specific RPM feature not otherwise anticipated by SCons needs to be turned on or off. Note if this variable is omitted, SCons will by default supply the value '%global debug_package %{nil}' to disable debug package generation. To enable debug package generation, include this variable set either to None, or to a custom list that does not include the default line.

    New in version 3.1.

        env.Package(
            NAME="foo",
            ...
            X_RPM_EXTRADEFS=[
                "%define _unpackaged_files_terminate_build 0"
                "%define _missing_doc_files_terminate_build 0"
            ],
            ...
        )

X_RPM_GROUP
    This is used to fill in the Group: field in the RPM .spec file.

X_RPM_GROUP_lang
    This is used to fill in the Group(lang): field in the RPM .spec file. Note that lang is not literal and should be replaced by the appropriate language code.

X_RPM_ICON
    This is used to fill in the Icon: field in the RPM .spec file.

X_RPM_INSTALL
    internal, but overridable

X_RPM_PACKAGER
    This is used to fill in the Packager: field in the RPM .spec file.

X_RPM_POSTINSTALL
    This is used to fill in the %post: section in the RPM .spec file.

X_RPM_POSTUNINSTALL
    This is used to fill in the %postun: section in the RPM .spec file.

X_RPM_PREFIX
    This is used to fill in the Prefix: field in the RPM .spec file.

X_RPM_PREINSTALL
    This is used to fill in the %pre: section in the RPM .spec file.

X_RPM_PREP
    internal, but overridable

X_RPM_PREUNINSTALL
    This is used to fill in the %preun: section in the RPM .spec file.

X_RPM_PROVIDES
    This is used to fill in the Provides: field in the RPM .spec file.

X_RPM_REQUIRES
    This is used to fill in the Requires: field in the RPM .spec file.

X_RPM_SERIAL
    This is used to fill in the Serial: field in the RPM .spec file.

X_RPM_URL
    This is used to fill in the Url: field in the RPM .spec file.

XGETTEXT
    Path to xgettext(1) program (found via Detect()). See xgettext tool and POTUpdate builder.

XGETTEXTCOM
    Complete xgettext command line. See xgettext tool and POTUpdate builder.

XGETTEXTCOMSTR
    A string that is shown when xgettext(1) command is invoked (default: '', which means "print $XGETTEXTCOM"). See xgettext tool and POTUpdate builder.

_XGETTEXTDOMAIN
    Internal "macro". Generates xgettext domain name form source and target (default: '${TARGET.filebase}').

XGETTEXTFLAGS
    Additional flags to xgettext(1). See xgettext tool and POTUpdate builder.

XGETTEXTFROM
    Name of file containing list of xgettext(1)'s source files. Autotools' users know this as POTFILES.in so they will in most cases set XGETTEXTFROM="POTFILES.in" here. The $XGETTEXTFROM files have same syntax and semantics as the well known GNU POTFILES.in. See xgettext tool and POTUpdate builder.

_XGETTEXTFROMFLAGS
    Internal "macro". Genrates list of -D<dir> flags from the $XGETTEXTPATH list.

XGETTEXTFROMPREFIX
    This flag is used to add single $XGETTEXTFROM file to xgettext(1)'s commandline (default: '-f').

XGETTEXTFROMSUFFIX
    (default: '')

XGETTEXTPATH
    List of directories, there xgettext(1) will look for source files (default: []).

        Note
        This variable works only together with $XGETTEXTFROM

    See also xgettext tool and POTUpdate builder.

_XGETTEXTPATHFLAGS
    Internal "macro". Generates list of -f<file> flags from $XGETTEXTFROM.

XGETTEXTPATHPREFIX
    This flag is used to add single search path to xgettext(1)'s commandline (default: '-D').

XGETTEXTPATHSUFFIX
    (default: '')

YACC
    The parser generator.

YACC_GRAPH_FILE
    If supplied, write a graph of the automaton to a file with the name taken from this variable. Will be emitted as a --graph= command-line option. Use this in preference to including --graph= in $YACCFLAGS directly.

    New in version 4.4.0.

YACC_GRAPH_FILE_SUFFIX
    Previously specified by $YACCVCGFILESUFFIX.

    The suffix of the file containing a graph of the grammar automaton when the -g option (or --graph= without an option-argument) is used in $YACCFLAGS. Note that setting this variable informs SCons how to construct the graph filename for tracking purposes, it does not affect the actual generated filename. Various yacc tools have emitted various formats at different times. Set this to match what your parser generator produces.

    New in version 4.6.0.

YACC_HEADER_FILE
    If supplied, generate a header file with the name taken from this variable. Will be emitted as a --header= command-line option. Use this in preference to including --header= in $YACCFLAGS directly.

    New in version 4.4.0.

YACCCOM
    The command line used to call the parser generator to generate a source file.

YACCCOMSTR
    The string displayed when generating a source file using the parser generator. If this is not set, then $YACCCOM (the command line) is displayed.

        env = Environment(YACCCOMSTR="Yacc'ing $TARGET from $SOURCES")

YACCFLAGS
    General options passed to the parser generator. In addition to passing the value on during invocation, the yacc tool also examines this construction variable for options which cause additional output files to be generated, and adds those to the target list.

    If the -d option is present in $YACCFLAGS scons assumes that the call will also create a header file with the suffix defined by $YACCHFILESUFFIX if the yacc source file ends in a .y suffix, or a file with the suffix defined by $YACCHXXFILESUFFIX if the yacc source file ends in a .yy suffix. The header will have the same base name as the requested target. This is only correct if the executable is bison (or win_bison). If using Berkeley yacc (byacc), y.tab.h is always written - avoid the -d in this case and use $YACC_HEADER_FILE instead.

    If a -g option is present, scons assumes that the call will also create a graph file with the suffix defined by $YACCVCGFILESUFFIX.

    If a -v option is present, scons assumes that the call will also create an output debug file with the suffix .output.

    Also recognized are GNU bison options --header (and its deprecated synonym --defines), which is similar to -d but gives the option to explicitly name the output header file through an option argument; and --graph, which is similar to -g but gives the option to explicitly name the output graph file through an option argument. The file suffixes described for -d and -g above are not applied if these are used in the option=argument form.

    Note that files specified by --header= and --graph= may not be properly handled by SCons in all situations, and using those in $YACCFLAGS should be considered legacy support only. Consider using $YACC_HEADER_FILE and $YACC_GRAPH_FILE instead if the files need to be explicitly named (new in version 4.4.0).

YACCHFILESUFFIX
    The suffix of the C header file generated by the parser generator when the -d option (or --header without an option-argument) is used in $YACCFLAGS. Note that setting this variable informs SCons how to construct the header filename for tracking purposes, it does not affect the actual generated filename. Set this to match what your parser generator produces. The default value is .h.

YACCHXXFILESUFFIX
    The suffix of the C++ header file generated by the parser generator when the -d option (or --header without an option-argument) is used in $YACCFLAGS. Note that setting this variable informs SCons how to construct the header filename for tracking purposes, it does not affect the actual generated filename. Set this to match what your parser generator produces. The default value is .hpp.

YACCVCGFILESUFFIX
    Obsoleted. Use $YACC_GRAPH_FILE_SUFFIX instead. The value is used only if $YACC_GRAPH_FILE_SUFFIX is not set. The default value is .gv.

    Changed in version 4.6.0: deprecated. The default value changed from .vcg (bison stopped generating .vcg output with version 2.4, in 2006).

ZIP
    The zip compression and file packaging utility.

ZIP_OVERRIDE_TIMESTAMP
    An optional timestamp which overrides the last modification time of the file when stored inside the Zip archive. This is a tuple of six values: Year (>= 1980) Month (one-based) Day of month (one-based) Hours (zero-based) Minutes (zero-based) Seconds (zero-based)

ZIPCOM
    The command line used to call the zip utility, or the internal Python function used to create a zip archive.

ZIPCOMPRESSION
    The compression flag from the Python zipfile module used by the internal Python function to control whether the zip archive is compressed or not. The default value is zipfile.ZIP_DEFLATED, which creates a compressed zip archive. This value has no effect if the zipfile module is unavailable.

ZIPCOMSTR
    The string displayed when archiving files using the zip utility. If this is not set, then $ZIPCOM (the command line or internal Python function) is displayed.

        env = Environment(ZIPCOMSTR = "Zipping $TARGET")

ZIPFLAGS
    General options passed to the zip utility.

ZIPROOT
    An optional zip root directory (default empty). The filenames stored in the zip file will be relative to this directory, if given. Otherwise the filenames are relative to the current directory of the command. For instance:

        env = Environment()
        env.Zip('foo.zip', 'subdir1/subdir2/file1', ZIPROOT='subdir1')

    will produce a zip file foo.zip containing a file with the name subdir2/file1 rather than subdir1/subdir2/file1.

ZIPSUFFIX
    The suffix used for zip file names.

  Configure Contexts

SCons supports a configure context, an integrated mechanism similar to the various AC_CHECK macros in GNU Autoconf for testing the existence of external items needed for the build, such as C header files, libraries, etc. The mechanism is portable across platforms.

scons does not maintain an explicit cache of the tested values (this is different than Autoconf), but uses its normal dependency tracking to keep the checked values up to date. However, users may override this behaviour with the --config command line option.

Configure(env, [custom_tests, conf_dir, log_file, config_h, clean, help]), env.Configure([custom_tests, conf_dir, log_file, config_h, clean, help])
    Create a configure context, which tracks information discovered while running tests. The context includes a local construction environment (available as context.env) which is used when running the tests and which can be updated with the check results. Only one context may be active at a time, but a new context can be created after the active one is completed. For the global function form, the required env describes the initial values for the context's local construction environment; for the construction environment method form the instance provides the values.

    Changed in version 4.0: raises an exception on an attempt to create a new context when there is an active context.

    custom_tests specifies a dictionary containing custom checks (see details below). The default value is None, to indicate there are no custom checks in the configure context.

    conf_dir specifies a directory where the test cases are built. This directory is not used for building normal targets. The default value is “#/.sconf_temp”.

    log_file specifies a file which collects the output from commands that are executed to check for the existence of header files, libraries, etc. The default is “#/config.log”. If you are using variant directories, you may want to place the log file for a given build under that build's variant directory.

    config_h specifies a C header file where the results of tests will be written. The results will consist of lines like #define HAVE_STDIO_H, #define HAVE_LIBM, etc. Customarily, the name chosen is “config.h”. The default is to not write a config_h file. You can specify the same config_h file in multiple calls to Configure, in which case SCons will concatenate all results in the specified file. Note that SCons uses its normal dependency checking to decide if it's necessary to rebuild the specified config_h file. This means that the file is not necessarily re-built each time scons is run, but is only rebuilt if its contents will have changed and some target that depends on the config_h file is being built.

    The clean and help arguments can be used to suppress execution of the configuration tests when the -c/--clean or -H/-h/--help options are used, respectively. The default behavior is always to execute configure context tests, since the results of the tests may affect the list of targets to be cleaned or the help text. If the configure tests do not affect these, then you may add the clean=False or help=False arguments (or both) to avoid unnecessary test execution.

context.Finish()
    This method must be called after configuration is done. Though required, this is not enforced except if Configure is called again while there is still an active context, in which case an exception is raised. Finish returns the environment as modified during the course of running the configuration checks. After this method is called, no further checks can be performed with this configuration context. However, you can create a new configure context to perform additional checks.

Example of a typical Configure usage:

    env = Environment()
    conf = Configure(env)
    if not conf.CheckCHeader("math.h"):
        print("We really need math.h!")
        Exit(1)
    if conf.CheckLibWithHeader("qt", "qapp.h", "c++", "QApplication qapp(0,0);"):
        # do stuff for qt - usage, e.g.
        conf.env.Append(CPPDEFINES="WITH_QT")
    env = conf.Finish()

A configure context has the following predefined methods which can be used to perform checks. Where language is an optional parameter, it specifies the compiler to use for the check, currently a choice of C or C++. The spellings accepted for C are “C” or “c”; for C++ the value can be “CXX”, “cxx”, “C++” or “c++”. If language is omitted, “C” is assumed.

context.CheckHeader(header, [include_quotes, language])
    Checks if header is usable in the specified language. header may be a list, in which case the last item in the list is the header file to be checked, and the previous list items are header files whose #include lines should precede the header line being checked for. The optional argument include_quotes must be a two character string, where the first character denotes the opening quote and the second character denotes the closing quote. By default, both characters are " (double quote).

    Returns a boolean indicating success or failure.

context.CheckCHeader(header, [include_quotes])
    Checks if header is usable when compiling a C language program. header may be a list, in which case the last item in the list is the header file to be checked, and the previous list items are header files whose #include lines should precede the header line being checked for. The optional argument include_quotes must be a two character string, where the first character denotes the opening quote and the second character denotes the closing quote. By default, both characters are " (double quote). Note this is a wrapper around CheckHeader. Returns a boolean indicating success or failure.

context.CheckCXXHeader(header, [include_quotes])
    Checks if header is usable when compiling a C++ language program. header may be a list, in which case the last item in the list is the header file to be checked, and the previous list items are header files whose #include lines should precede the header line being checked for. The optional argument include_quotes must be a two character string, where the first character denotes the opening quote and the second character denotes the closing quote. By default, both characters are " (double quote). Note this is a wrapper around CheckHeader. Returns a boolean indicating success or failure.

context.CheckFunc(function_name, [header, language, funcargs])
    Checks if function_name is usable in the context's local environment, using the compiler specified by language - that is, can a check referencing it be compiled using the current values of $CFLAGS, $CPPFLAGS, $LIBS or other relevant construction variables.

    The optional header argument is a string representing a code fragment to place at the top of the test program that will be compiled to check if the function exists. If omitted, the default stanza will be (with function_name appropriately substituted):

        #ifdef __cplusplus
        extern "C"
        #endif
        char function_name(void);

    If header is supplied, it should not include the standard header file that declares function_name and it should include a dummy prototype similar to the default case. If this is not possible, the optional funcargs argument can be used to specify a string containing an argument list with the same number and type of arguments as the prototype. The arguments can simply be constant values of the correct type. Modern C/C++ compilers reject implicit function declarations and may also reject function calls whose arguments are not type compatible with the prototype.

    Changed in version 4.7.0: added the funcargs.

    Returns a boolean indicating success or failure.

context.CheckLib([library, symbol, header, language, autoadd=True, append=True, unique=False])
    Checks if library provides symbol by compiling a simple stub program with the compiler selected by language, and optionally adds that library to the context. If supplied, the text of header is included at the top of the stub. If autoadd is true (the default), and the library provides the specified symbol (as defined by successfully linking the stub program), it is added to the $LIBS construction variable in the context. if append is true (the default), the library is appended, otherwise it is prepended. If unique is true, and the library would otherwise be added but is already present in $LIBS in the configure context, it will not be added again. The default is False.

    library can be a list of library names, or None (the default if the argument is omitted). If the former, symbol is checked against each library name in order, returning (and reporting success) on the first successful test; if the latter, it is checked with the current value of $LIBS (in this case no library name would be added). If symbol is omitted or None, then CheckLib just checks if you can link against the specified library, Note though it is legal syntax, it would not be very useful to call this method with library and symbol both omitted or None - at least one should be supplied.

    Returns a boolean indicating success or failure.

    Changed in version 4.5.0: added the append and unique parameters.

context.CheckLibWithHeader(library, header, [language, call, autoadd=True, append=True, unique=False])
    Provides an alternative to the CheckLib method for checking for libraries usable in a build. library specifies a library or list of libraries to check. header specifies a header to include in the test program, and language indicates the compiler to use. header may be a list, in which case the last item in the list is the header file to be checked, and the previous list items are header files whose #include lines should precede the header line being checked for. A code fragment (must be a a valid expression, including a trailing semicolon) to serve as the test can be supplied in call; if not supplied, the default checks the ability to link against the specified library. If autoadd is true (the default), the first library that passes the check is added to the $LIBS construction variable in the context and the method returns. If append is true (the default), the library is appended, otherwise prepended. If unique is true, and the library would otherwise be added but is already present in $LIBS in the configure context, it will not be added again. The default is False.

    Returns a boolean indicating success or failure.

    Changed in version 4.5.0: added the append and unique parameters.

context.CheckType(type_name, [includes, language])
    Checks for the existence of a type defined by typedef. type_name specifies the typedef name to check for. includes is a string containing one or more #include lines that will be inserted into the program that will be run to test for the existence of the type. Example:

        sconf.CheckType('foo_type', '#include "my_types.h"', 'C++')

    Returns a boolean indicating success or failure.

context.CheckTypeSize(type_name, [header, language, expect])
    Checks for the size of a type defined by typedef. type_name specifies the typedef name to check for. The optional header argument is a string that will be placed at the top of the test file that will be compiled to check if the type exists; the default is empty. If the optional expect, is supplied, it should be an integer size; CheckTypeSize will fail unless type_name is actually that size. Returns the size in bytes, or zero if the type was not found (or if the size did not match optional expect).

    For example,

        CheckTypeSize('short', expect=2)

    will return the size 2 only if short is actually two bytes.

context.CheckCC()
    Checks whether the C compiler (as defined by the $CC construction variable) works, by trying to compile a small source file. This provides a more rigorous check: by default, SCons itself only detects if there is a program with the correct name, not if it is a functioning compiler. Returns a boolean indicating success or failure.

    The test program will be built with the same command line as the one used by the Object builder for C source files, so by setting relevant construction variables it can be used to detect if particular compiler flags will be accepted or rejected by the compiler.

    Returns a boolean indicating success or failure.

context.CheckCXX()
    Checks whether the C++ compiler (as defined by the $CXX construction variable) works, by trying to compile a small source file. This provides a more rigorous check: by default, SCons itself only detects if there is a program with the correct name, not if it is a functioning compiler. Returns a boolean indicating success or failure.

    The test program will be built with the same command line as the one used by the Object builder for C++ source files, so by setting relevant construction variables it can be used to detect if particular compiler flags will be accepted or rejected by the compiler.

    Returns a boolean indicating success or failure.

context.CheckSHCC()
    Checks whether the shared-object C compiler (as defined by the $SHCC construction variable) works by trying to compile a small source file. This provides a more rigorous check: by default, SCons itself only detects if there is a program with the correct name, not if it is a functioning compiler. Returns a boolean indicating success or failure.

    The test program will be built with the same command line as the one used by the SharedObject builder for C source files, so by setting relevant construction variables it can be used to detect if particular compiler flags will be accepted or rejected by the compiler. Note this does not check whether a shared library/dll can be created.

    Returns a boolean indicating success or failure.

context.CheckSHCXX()
    Checks whether the shared-object C++ compiler (as defined by the $SHCXX construction variable) works by trying to compile a small source file. This provides a more rigorous check: by default, SCons itself only detects if there is a program with the correct name, not if it is a functioning compiler. Returns a boolean indicating success or failure.

    The test program will be built with the same command line as the one used by the SharedObject builder for C++ source files, so by setting relevant construction variables it can be used to detect if particular compiler flags will be accepted or rejected by the compiler. Note this does not check whether a shared library/dll can be created.

    Returns a boolean indicating success or failure.

context.CheckProg(prog_name)
    Checks if prog_name exists in the path SCons will use at build time. (context.env['ENV']['PATH']). Returns a string containing the path to the program, or None on failure.

context.CheckDeclaration(symbol, [includes, language])
    Checks if the specified symbol is declared. includes is a string containing one or more #include lines that will be inserted into the program that will be run to test for the existence of the symbol.

    Returns a boolean indicating success or failure.

context.CheckMember(aggregate_member, [header, language])
    Checks for the existence of a member of the C/C++ struct or class. aggregate_member specifies the struct/class and member to check for. header is a string containing one or more #include lines that will be inserted into the program that will be run to test for the existence of the member. Example:

        sconf.CheckMember('struct tm.tm_sec', '#include <time.h>')

    Returns a boolean indicating success or failure.

context.Define(symbol, [value, comment])
    This method does not check for anything, but rather forces the definition of a preprocessor macro that will be added to the configuration header file. name is the macro's identifier. If value is given, it will be be used as the macro replacement value. If value is a string and needs to display with quotes, the quotes need to be included, as in '"string"' If the optional comment is given, it is inserted as a comment above the macro definition (suitable comment marks will be added automatically). This is analogous to using AC_DEFINE in Autoconf.

    Examples:

        env = Environment()
        conf = Configure(env)
        # Puts the following line in the config header file:
        #    #define A_SYMBOL
        conf.Define("A_SYMBOL")
        # Puts the following line in the config header file:
        #    #define A_SYMBOL 1
        conf.Define("A_SYMBOL", 1)

    Examples of quoting string values:

        env = Environment()
        conf = Configure(env)
        # Puts the following line in the config header file:
        #    #define A_SYMBOL YA
        conf.Define("A_SYMBOL", "YA")
        # Puts the following line in the config header file:
        #    #define A_SYMBOL "YA"
        conf.Define("A_SYMBOL", '"YA"')

    Example including comment:

        env = Environment()
        conf = Configure(env)
        # Puts the following lines in the config header file:
        #    /* Set to 1 if you have a symbol */
        #    #define A_SYMBOL 1
        conf.Define("A_SYMBOL", 1, "Set to 1 if you have a symbol")

You can define your own custom checks in addition to using the predefined checks. To enable custom checks, pass a dictionary to the Configure function as the custom_tests parameter. The dictionary maps the names of the checks to the custom check callables (either a Python function or an instance of a class implementing a __call__ method). Each custom check will be called with a a CheckContext instance as the first parameter followed by the remaining arguments, which must be supplied by the user of the check. A CheckContext is not the same as a configure context; rather it is an instance of a class which contains a configure context (available as chk_ctx.sconf). A CheckContext provides the following methods which custom checks can make use of::

chk_ctx.Message(text)
    Displays text as an indicator of progess. For example: Checking for library X.... Usually called before the check is started.

chk_ctx.Result(res)
    Displays a result message as an indicator of progress. If res is an integer, displays yes if res evaluates true or no if false. If res is a string, it is displayed as-is. Usually called after the check has completed.

chk_ctx.TryCompile(text, extension='')
    Checks if a file containing text and given the specified extension (e.g. '.c') can be compiled to an object file using the environment's Object builder. Returns a boolean indicating success or failure.

chk_ctx.TryLink(text, extension='')
    Checks if a file containing text and given the specified extension (e.g. '.c') can be compiled to an executable program using the environment's Program builder. Returns a boolean indicating success or failure.

chk_ctx.TryRun(text, extension='')
    Checks if a file containing text and given the specified extension (e.g. '.c') can be compiled to an excutable program using the environment's Program builder and subsequently executed. Execution is only attempted if the build succeeds. If the program executes successfully (that is, its return status is 0), a tuple (True, outputStr) is returned, where outputStr is the standard output of the program. If the program fails execution (its return status is non-zero), then (False, '') is returned.

chk_ctx.TryAction(action, [text, extension=''])
    Checks if the specified action with an optional source file (contents text, given extension extension) can be executed. action may be anything which can be converted to an Action Object. On success, a tuple (True, outputStr) is returned, where outputStr is the content of the target file. On failure (False, '') is returned.

chk_ctx.TryBuild(builder, [text, extension=''])
    Low level implementation for testing specific builds; the methods above are based on this method. Given the Builder instance builder and the optional text of a source file with optional extension, returns a boolean indicating success or failure. In addition, chk_ctx.lastTarget is set to the build target node if the build was successful.

Example of implementing and using custom checks:

    def CheckQt(chk_ctx, qtdir):
        chk_ctx.Message('Checking for qt ...')
        lastLIBS = chk_ctx.env['LIBS']
        lastLIBPATH = chk_ctx.env['LIBPATH']
        lastCPPPATH = chk_ctx.env['CPPPATH']
        chk_ctx.env.Append(LIBS='qt', LIBPATH=qtdir + '/lib', CPPPATH=qtdir + '/include')
        ret = chk_ctx.TryLink(
            """\
    #include <qapp.h>
    int main(int argc, char **argv) {
      QApplication qapp(argc, argv);
      return 0;
    }
    """
        )
        if not ret:
            chkctx.env.Replace(LIBS=lastLIBS, LIBPATH=lastLIBPATH, CPPPATH=lastCPPPATH)
        chkctx.Result(ret)
        return ret
    env = Environment()
    conf = Configure(env, custom_tests={'CheckQt': CheckQt})
    if not conf.CheckQt('/usr/lib/qt'):
        print('We really need qt!')
        Exit(1)
    env = conf.Finish()

  Command-Line Construction Variables

Often when building software, specialized information needs to be conveyed at build time to override the defaults in the build scripts. Command-line arguments (like --implcit-cache) and giving names of build targets are two ways to do that. Another is to provide variable-assignment arguments on the command line. For the particular case where you want to specify new values for construction variables, SCons provides a Variables object to simplify collecting those and updating a construction environment with the values. The typical calling style looks like:

    scons VARIABLE=foo

Variables specified in the above way can be manually processed by accessing the ARGUMENTS dictionary (or ARGLIST list), but using a Variables object allows you to describe anticipated variables, convert them to a suitable type if necessary, validate the values are within defined constraints, and define defaults, help messages and aliases. This is conceptually similar to the structure of options (see AddOption). It also allows obtaining values from a saved variables file, or from a custom dictionary in an SConscript file. The processed variables can then be applied to the desired construction environment.

Roughly speaking, arguments are used to convey information to the SCons program about how it should behave; variables are used to convey information to the build (although SCons does not enforce any such constraint).

To obtain an object for manipulating variables, call the Variables factory function:

Variables([files, [args]])
    If files is a filename or list of filenames, they are considered to be Python scripts which will be executed to set variables when the Update method is called - this allows the use of Python syntax in the assignments. A file can be the result of an earlier call to the Save method. If files is not specified, or the files argument is None, then no files will be read. Supplying None is required if there are no files but you want to specify args as a positional argument; this can be omitted if using the keyword argument style. If any of files is missing, it is silently skipped.

    Either of the following example file contents could be used to set an alternative C compiler:

        CC = 'my_cc'
        CC = os.environ.get('CC')

    If args is specified, it must be a dictionary. The key-value pairs from args will be added to those obtained from files, if any. Keys from args take precendence over same-named keys from files. If omittted, the default is the ARGUMENTS dictionary that holds build variables specified on the command line. Using ARGUMENTS allows you to indicate that if a setting appears on both the command line and in the file(s), the command line setting is preferred. However, any dictionary can be passed. Examples:

        vars = Variables('custom.py')
        vars = Variables('overrides.py', ARGUMENTS)
        vars = Variables(None, {FOO:'expansion', BAR:7})
        vars = Variables(args={FOO:'expansion', BAR:7})

    Calling Variables with no arguments is equivalent to:

        vars = Variables(files=None, args=ARGUMENTS)

A Variables object serves as a container for descriptions of variables, which are added by calling methods of the object. Each variable consists of a name (which will become a construction variable), aliases for the name, a help message, a default value, and functions to validate and convert values. Once the object is asked to process variables, it matches up data from the input sources it was given with the definitions, and generates key-value pairs which are added to the specified construction environment, except that if any variable was described to have a default of None, it is not added to the construction environment unless it appears in the input sources. Otherwise, a variable not in the input sources is added using its default value.

Note that since the variables are eventually added as construction variables, you should choose variable names which do not unintentionally change pre-defined construction variables that your project will make use of (see the section called “Construction Variables” for a reference), since variables obtained have values overridden, not merged.

Also note there is currently no way to use the Variables mechanism to define a variable which the user is required to supply; if necessary this can be implemented by accessing ARGUMENTS directly, although that only applies to the command line, not to any stored-values files.

A Variables object has the following methods:

vars.Add(key, [help, default, validator, converter, subst])
    Add a customizable construction variable to the Variables object. key is either the name of the variable, or a sequence of strings, in which case the first item in the sequence is taken as the variable name, and any remaining values are considered aliases for the variable. key is mandatory, there is no default. help is the help text for the variable (defaults to an empty string). default is the default value of the variable (defaults to None).

    If the optional validator argument is supplied, it is a callback function to validate the value of the variable when the variables are processed (that is, when the Update method runs). A validator function must accept three arguments: key, value and env, and should raise an exception (with a helpful error message) if value is invalid. No return value is expected from the validator.

    If the optional converter argument is supplied, it is a callback function to convert the value into one suitable for adding to the construction environment. A converter function must accept the value argument, and may declare env as a second argument if it needs access to the construction environment while validating - the function will be called appropriately. The converter is called before the validator; it must return a value, which is then passed to the validator (if any) for checking. In general, the converter should not fail, leaving validation checks to the validator, although if an operation is impossible to complete or there is no separate validator it can raise a ValueError.

    Substitution will be performed on the variable value before the converter and validator are called, unless the optional subst parameter is false (default True). Suppressing substitution may be useful if the variable value looks like a construction variable reference (e.g. $VAR) and the validator and/or converter should see it unexpanded.

    As a special case, if key is a sequence and is the only argument to Add, it is unpacked into the five parameters key, help, default, validator and converter, with any missing members from the right filled in with the respective default values. This form allows it to consume a tuple emitted by the convenience functions BoolVariable, EnumVariable, ListVariable, PackageVariable and PathVariable.

    Examples:

        vars.Add('CC', help='The C compiler')
        def valid_color(key, val, env):
            if not val in ['red', 'blue', 'yellow']:
                raise Exception("Invalid color value '%s'" % val)
        vars.Add('COLOR', validator=valid_color)

    Changed in version 4.8.0: added the subst parameter.

vars.AddVariables(args)
    A convenience method that adds one or more customizable construction variables to a Variables object in one call; equivalent to calling Add multiple times. Each args member must be a tuple that contains the arguments for an individual call to the Add method using the "special case" form; the other calling styles (individual positional arguments and/or keyword arguments) are not supported.

        opt.AddVariables(
            ("debug", "", 0),
            ("CC", "The C compiler"),
            ("VALIDATE", "An option for testing validation", "notset", validator, None),
        )

vars.Update(env, [args])
    Process the input sources recorded when the Variables object was initialized and update env with the customized construction variables. The names of any variables in the input sources that are not configured in the Variables object are recorded and may be retrieved using the UnknownVariables method.

    If the optional args argument is provided, it is a dictionary of variables to use in place of the one saved when Variables was called.

    Normally, Update is not called directly, but rather invoked indirectly by passing the Variables object to the Environment function:

        env = Environment(..., variables=vars)

vars.UnknownVariables()
    Returns a dictionary containing any variables that were specified in the files and/or args parameters when Variables was called, but the object was not actually configured for. This information is not available until the Update method has run.

        env = Environment(variables=vars)
        for key, value in vars.UnknownVariables():
            print("unknown variable:  %s=%s" % (key, value))

vars.Save(filename, env)
    Saves the currently set variables into a script file named by filename. This provides a way to cache particular variable settings for reuse. Only variables that are set to non-default values are saved. You can load these saved variables on a subsequent run by passing filename to the Variables function,

        env = Environment()
        vars = Variables(['variables.cache', 'custom.py'])
        vars.Add(...)
        vars.Update(env)
        vars.Save('variables.cache', env)

vars.GenerateHelpText(env, [sort])
    Return a formatted string with the help text collected from all the variables configured in this Variables object. This string is suitable for passing in to the Help function. The generated string include an indication of the actual value in the environment given by env.

    If the optional sort parameter is set to a callable value, it is used as a comparison function to determine how to sort the added variables. This function must accept two arguments, compare them, and return a negative integer if the first is less-than the second, zero if equal, or a positive integer if greater-than. If sort is not callable, but is set to True, an alphabetical sort is performed. The default is False (unsorted).

        Help(vars.GenerateHelpText(env))
        def cmp(a, b):
            return (a > b) - (a < b)
        Help(vars.GenerateHelpText(env, sort=cmp))

vars.FormatVariableHelpText(env, opt, help, default, actual)
    Returns a formatted string containing the printable help text for the single option opt. It is normally not called directly, but is called by the GenerateHelpText method to create the returned help text. It may be overridden with your own function that takes the arguments specified above and returns a string of help text formatted to your liking. Note that GenerateHelpText will not put any blank lines or extra characters in between the entries, so you must add those characters to the returned string if you want the entries separated.

        def my_format(env, opt, help, default, actual):
            fmt = "\n%s: default=%s actual=%s (%s)\n"
            return fmt % (opt, default, actual, help)
        vars.FormatVariableHelpText = my_format

To make it more convenient to describe custom variables, SCons provides some pre-defined variable types, acessible through factory functions that generate a tuple appropriate for directly passing to the Add or AddVariables method:

BoolVariable(key, help, default)
    Set up a Boolean variable. The variable will use the specified name key, have a default value of default, and help will form the descriptive part of the help text. The variable will interpret the command-line values y, yes, t, true, 1, on and all as true, and the command-line values n, no, f, false, 0, off and none as false.

EnumVariable(key, help, default, allowed_values, [map, ignorecase])
    Set up a variable whose value may only be from a specified list ("enumeration") of values. The variable will have the name key, have a default value of default and help will form the descriptive part of the help text. Any value that is not in allowed_values will raise an error, except that the optional map argument is a dictionary that can be used to map additional names into a particular name in the allowed_values list. If the value of optional ignore_case is 0 (the default), then the values are case-sensitive. If the value of ignore_case is 1, then values will be matched case-insensitively. If the value of ignore_case is 2, then values will be matched case-insensitively, and all input values will be converted to lower case.

ListVariable(key, help, default, names, [map, validator])
    Set up a variable whose value may be one or more from a specified list of values. The variable will have the name key, have a default value of default, and help will form the descriptive part of the help text. Any value that is not in names or the special values all or none will raise an error. More than one value may be specified, separated by commas. default may be specified either as a string of comma-separated value, or as a list of values.

    The optional map argument is a dictionary that can be used to convert input values into specific legal values in the names list. (Note that the additional values accepted through the use of a map are not reflected in the generated help message).

    The optional validator argument can be used to specify a custom validator callback function, as described for Add. The default is to use an internal validator routine.

    New in 4.8.0: validator.

PackageVariable(key, help, default)
    Set up a variable for a package, where if the variable is specified, the construction variable named by key will end with a value of True, False, or a user-specified value. For example, a package could be a third-party software component, the build could use the information to exclude the package, include the package in the standard way, or include the package using a specified directory path to find the package files.

    The variable will have a default value default, and help will form the descriptive part of the help text. The variable supports (case-insensitive) truthy values 1, yes, true, on, enable and search to indicate the package is "enabled", and the (case-insensitive) falsy values 0, no, false, off and disable to indicate the package is "disabled".

    The value of the variable may also be set to an arbitrary string, which is taken to be the path name to the package that is being enabled. The validator will raise an exception if this path does not exist in the filesystem.

PathVariable(key, help, default, [validator])
    Set up a variable whose value is expected to be a path name. The construction variable named by key will have have a default value of default, and help will form the descriptive part of the help text.

    An optional validator argument may be specified. The validator will be called to verify that the specified path is acceptable. SCons supplies the following ready-made validators:

    PathVariable.PathExists
        Verify that the specified path exists (this the default behavior if no validator is supplied).

    PathVariable.PathIsFile
        Verify that the specified path exists and is a regular file.

    PathVariable.PathIsDir
        Verify that the specified path exists and is a directory.

    PathVariable.PathIsDirCreate
        Verify that the specified path exists and is a directory; if it does not exist, create the directory.

    PathVariable.PathAccept
        Accept the specific path name argument without validation, suitable for when you want your users to be able to specify a directory path that will be created as part of the build process, for example.

    You may supply your own validator function, which must accept three arguments: key, the name of the variable to be set; val, the specified value being checked; and env, the construction environment, and should raise an exception if the specified value is not acceptable.

These functions make it convenient to create a number of variables with consistent behavior in a single call to the AddVariables method:

    vars.AddVariables(
        BoolVariable(
            "warnings",
            help="compilation with -Wall and similar",
            default=True,
        ),
        EnumVariable(
            "debug",
            help="debug output and symbols",
            default="no",
            allowed_values=("yes", "no", "full"),
            map={},
            ignorecase=0,  # case sensitive
        ),
        ListVariable(
            "shared",
            help="libraries to build as shared libraries",
            default="all",
            names=list_of_libs,
        ),
        PackageVariable(
            "x11",
            help="use X11 installed here (yes = search some places)",
            default="yes",
        ),
        PathVariable(
            "qtdir",
            help="where the root of Qt is installed",
            default=qtdir),
        PathVariable(
            "foopath",
            help="where the foo library is installed",
            default=foopath,
            validator=PathVariable.PathIsDir,
        ),
    )

  Node Objects

SCons represents objects that are the sources or targets of build operations as Nodes, which are internal data structures. There are a number of user-visible types of nodes: File Nodes, Directory Nodes, Value Nodes and Alias Nodes. Some of the node types have public attributes and methods, described below. Each of the node types has a global function and a matching environment method to create instances: File, Dir, Value and Alias.

Filesystem Nodes

    The File and Dir functions/methods return File Nodes and Directory Nodes, respectively. Such Filesystem Nodes represent build components that correspond to an entry in the computer's filesystem, whether or not such an entry exists at the time the Node is created. You do not usually need to explicitly create filesystem Nodes, since when you supply a string as a target or source of a Builder, SCons will create the Nodes as needed to populate the dependency graph. Builders return the target Node(s) in the form of a list, which you can then make use of. However, since filesystem Nodes have some useful public attributes and methods that you can use in SConscript files, it is sometimes appropriate to create them manually, outside the regular context of a Builder call.

    The following attributes provide information about a Node:

    node.path
        The build path of the given file or directory. This path is relative to the project top directory. The build path is the same as the source path if variant_dir is not being used.

    node.abspath
        The absolute build path of the given file or directory.

    node.relpath
        The build path of the given file or directory relative to the project top directory.

    node.srcnode()
        The srcnode method returns another File or Directory Node representing the source path of the given File or Directory Node.

    Examples:

        # Get the current build dir's path, relative to top.
        Dir('.').path
        # Current dir's absolute path
        Dir('.').abspath
        # Current dir's path relative to the project top directory
        Dir('.').relpath
        # Next line is always '.', because it is the top dir's path relative to itself.
        Dir('#.').path
        # Source path of the given source file.
        File('foo.c').srcnode().path
        # Builders return lists of File objects:
        foo = env.Program('foo.c')
        print("foo will be built in", foo[0].path)

    Filesystem Node objects have methods to create new Filesystem Nodes relative to the original Node. There are also times when you may need to refer to an entry in a filesystem without knowing in advance whether it's a file or a directory. For those situations, there is an Entry method of filesystem node objects, which returns a Node that can represent either a file or a directory.

    If the original Node is a Directory Node, these methods will place the new Node within the directory the original Node represents:

    node.Dir(name)
        Returns a directory Node name which is a subdirectory of the directory represented by node.

    node.File(name)
        Returns a file Node name in the directory represented by node.

    node.Entry(name)
        Returns an unresolved Node name in the directory represented by node.

    If the original Node is a File Node, these methods will place the the new Node in the same directory as the one the original Node represents:

    node.Dir(name)
        Returns a Node name for a directory in the parent directory of the file represented by node.

    node.File(name)
        Returns a Node name for a file in the parent directory of the file represented by node.

    node.Entry(name)
        Returns an unresolved Node name in the parent directory of the file represented by node.

    For example:

        # Get a Node for a file within a directory
        incl = Dir('include')
        f = incl.File('header.h')
        # Get a Node for a subdirectory within a directory
        dist = Dir('project-3.2.1')
        src = dist.Dir('src')
        # Get a Node for a file in the same directory
        cfile = File('sample.c')
        hfile = cfile.File('sample.h')
        # Combined example
        docs = Dir('docs')
        html = docs.Dir('html')
        index = html.File('index.html')
        css = index.File('app.css')

Value and Alias Nodes

    SCons provides two other Node types to represent object that will not have an equivalent filesystem entry. Such Nodes always need to be created explicitly.

    The Alias method returns an Alias Node. Aliases are virtual objects - they will not themselves result in physical objects being constructed, but are entered into the dependency graph related to their sources. An alias is checked for up to date by checking if its sources are up to date. An alias is built by making sure its sources have been built, and if any building took place, applying any Actions that are defined as part of the alias.

    An Alias call creates an entry in the alias namespace, which is used for disambiguation. If an alias source has a string valued name, it will be resolved to a filesystem entry Node, unless it is found in the alias namespace, in which case it it resolved to the matching alias Node. As a result, the order of Alias calls is significant. An alias can refer to another alias, but only if the other alias has previously been created.

    The Value method returns a Value Node. Value nodes are often used for generated data that will not have any corresponding filesystem entry, but will be used to determine whether a build target is out of date, or to include as part of a build Action. Common examples are timestamp strings, revision control version strings and other run-time generated strings.

    A Value Node can also be the target of a builder.

EXTENDING SCONS

SCons is designed to be extensible through provided facilities, so changing the code of SCons itself is only rarely needed to customize its behavior. A number of the main operations use callable objects which can be supplemented by writing your own. Builders, Scanners and Tools each use a kind of plugin system, allowing you to easily drop in new ones. Information about creating Builder Objects and Scanner Objects appear in the following sections. The instructions SCons actually uses to construct things are called Actions, and it is easy to create Action Objects and hand them to the objects that need to know about those actions (besides Builders, see AddPostAction, AddPreAction and Alias for some examples of other places that take Actions). Action Objects are also described below. Adding new Tool modules is described in Tool Modules

  Builder Objects

scons can be extended to build different types of targets by adding new Builder objects to a construction environment. In general, you should only need to add a new Builder object when you want to build a new type of file or other external target. For output file types scons already knows about, you can usually modify the behavior of premade Builders such as Program, Object or Library by changing the construction variables they use ($CC, $LINK, etc.). In this manner you can, for example, change the compiler to use, which is simpler and less error-prone than writing a new builder. The documentation for each Builder lists which construction variables it uses.

Builder objects are created using the Builder factory function. Once created, a builder is added to an environment by entering it in the $BUILDERS dictionary in that environment (some of the examples in this section illustrate this). Doing so automatically triggers SCons to add a method with the name of the builder to the environment.

The Builder function accepts the following keyword arguments:

action
    The command used to build the target from the source. action may be a string representing a template command line to execute, a list of strings representing the command to execute with its arguments (suitable for enclosing white space in an argument), a dictionary mapping source file name suffixes to any combination of command line strings (if the builder should accept multiple source file extensions), a Python function, an Action object (see Action Objects) or a list of any of the above.

    An action function must accept three arguments: source, target and env. source is a list of source nodes; target is a list of target nodes; env is the construction environment to use for context.

    The action and generator arguments must not both be used for the same Builder.

prefix
    The prefix to prepend to the target file name. prefix may be a string, a function (or other callable) that takes two arguments (a construction environment and a list of sources) and returns a prefix string, or a dictionary specifying a mapping from a specific source suffix (of the first source specified) to a corresponding target prefix string. For the dictionary form, both the source suffix (key) and target prefix (value) specifications may use environment variable substitution, and the target prefix may also be a callable object. The default target prefix may be indicated by a dictionary entry with a key of None.

        b = Builder("build_it < $SOURCE > $TARGET", prefix="file-")
        def gen_prefix(env, sources):
            return "file-" + env['PLATFORM'] + '-'
        b = Builder("build_it < $SOURCE > $TARGET", prefix=gen_prefix)
        b = Builder(
            "build_it < $SOURCE > $TARGET",
            suffix={None: "file-", "$SRC_SFX_A": gen_prefix},
        )

suffix
    The suffix to append to the target file name. Specified in the same manner as for prefix above. If the suffix is a string, then scons prepends a '.' to the suffix if it's not already there. The string returned by the callable object or obtained from the dictionary is untouched and you need to manually prepend a '.' if one is required.

        b = Builder("build_it < $SOURCE > $TARGET", suffix="-file")
        def gen_suffix(env, sources):
            return "." + env['PLATFORM'] + "-file"
        b = Builder("build_it < $SOURCE > $TARGET", suffix=gen_suffix)
        b = Builder(
            "build_it < $SOURCE > $TARGET",
            suffix={None: ".sfx1", "$SRC_SFX_A": gen_suffix},
        )

ensure_suffix
    If set to a true value, ensures that targets will end in suffix. Thus, the suffix will also be added to any target strings that have a suffix that is not already suffix. The default behavior (also indicated by a false value) is to leave unchanged any target string that looks like it already has a suffix.

        b1 = Builder("build_it < $SOURCE > $TARGET", suffix=".out")
        b2 = Builder(
            "build_it < $SOURCE > $TARGET", suffix=".out", ensure_suffix=True
        )
        env = Environment()
        env['BUILDERS']['B1'] = b1
        env['BUILDERS']['B2'] = b2
        # Builds "foo.txt" because ensure_suffix is not set.
        env.B1('foo.txt', 'foo.in')
        # Builds "bar.txt.out" because ensure_suffix is set.
        env.B2('bar.txt', 'bar.in')

src_suffix
    The expected source file name suffix. src_suffix may be a string or a list of strings.

target_scanner
    A Scanner object that will be invoked to find implicit dependencies for this target file. Use only to specify Scanner objects that find implicit dependencies based on the target file and construction environment, not for implicit dependencies based on source files (use source_scanner for those). See the section called “Scanner Objects” for information about creating your own Scanner objects.

source_scanner
    A Scanner object that will be invoked to find implicit dependencies in any source files used to build this target file. Use to specify a scanner to find things like #include lines in source files. The pre-built DirScanner Scanner object may be used to indicate that this Builder should scan directory trees for on-disk changes to files that scons does not know about from other Builder or function calls. See the section called “Scanner Objects” for information about creating your own Scanner objects.

target_factory
    A factory function that the Builder will use to turn any targets specified as strings into SCons Nodes. By default, SCons assumes that all targets are files (that is, the default factory is File). Other useful target_factory values include Dir for when a Builder creates a directory target, and Entry for when a Builder can create either a file or directory target.

    Example:

        def my_mkdir(target, source, env):
            # target[0] will be a Dir node for 'new_directory'
        MakeDirectoryBuilder = Builder(action=my_mkdir, target_factory=Dir)
        env = Environment()
        env.Append(BUILDERS={'MakeDirectory': MakeDirectoryBuilder})
        env.MakeDirectory('new_directory', [])

    Note that the call to the MakeDirectory Builder needs to specify an empty source list to make the filename string represent the builder's target. SCons assumes a single positional argument to a builder is the source, and would try to deduce the target name from it, which, in the absence of an automatically-added prefix or suffix, would lead to a matching target and source name and a circular dependency.

source_factory
    A factory function that the Builder will use to turn any sources specified as strings into SCons Nodes. By default, SCons assumes that all source are files (that is, the default factory is File). Other useful source_factory values include Dir for when a Builder uses a directory as a source, and Entry for when a Builder can use files or directories (or both) as sources.

    Example:

        def collect(target, source, env):
            # target[0] will default to a File node for 'archive' (no target_factory)
            # source[0] will be a Dir node for 'directory_name'
        CollectBuilder = Builder(action=collect, source_factory=Dir)
        env = Environment()
        env.Append(BUILDERS={'Collect': CollectBuilder})
        env.Collect('archive', 'directory_name')

emitter
    A function or list of functions to manipulate the target and source lists before dependencies are established and the target(s) are actually built. emitter can also be a string containing a construction variable to expand to an emitter function or list of functions, or a dictionary mapping source file suffixes to emitter functions. (Only the suffix of the first source file is used to select the actual emitter function from an emitter dictionary.)

    A function passed as emitter must accept three arguments: source, target and env. source is a list of source nodes, target is a list of target nodes, env is the construction environment to use for context.

    An emitter must return a tuple containing two lists, the list of targets to be built by this builder, and the list of sources for this builder.

    Example:

        def e(target, source, env):
            return target + ['foo.foo'], source + ['foo.src']
        # Simple association of an emitter function with a Builder.
        b = Builder("my_build < $TARGET > $SOURCE", emitter=e)
        def e2(target, source, env):
            return target + ['bar.foo'], source + ['bar.src']
        # Simple association of a list of emitter functions with a Builder.
        b = Builder("my_build < $TARGET > $SOURCE", emitter=[e, e2])
        # Calling an emitter function through a construction variable.
        env = Environment(MY_EMITTER=e)
        b = Builder("my_build < $TARGET > $SOURCE", emitter='$MY_EMITTER')
        # Calling a list of emitter functions through a construction variable.
        env = Environment(EMITTER_LIST=[e, e2])
        b = Builder("my_build < $TARGET > $SOURCE", emitter='$EMITTER_LIST')
        # Associating multiple emitters with different file
        # suffixes using a dictionary.
        def e_suf1(target, source, env):
            return target + ['another_target_file'], source
        def e_suf2(target, source, env):
            return target, source + ['another_source_file']
        b = Builder(
            action="my_build < $TARGET > $SOURCE",
            emitter={'.suf1': e_suf1, '.suf2': e_suf2}
        )

multi
    Specifies whether this builder is allowed to be called multiple times for the same target file(s). The default is False, which means the builder can not be called multiple times for the same target file(s). Calling a builder multiple times for the same target simply adds additional source files to the target; it is not allowed to change the environment associated with the target, specify additional environment overrides, or associate a different builder with the target.

env
    A construction environment that can be used to fetch source code using this Builder. (Note that this environment is not used for normal builds of normal target files, which use the environment that was used to call the Builder for the target file.)

generator
    A function that returns a list of actions that will be executed to build the target(s) from the source(s). The returned action(s) may be an Action object, or anything that can be converted into an Action object (see the next section).

    A function passed as generator must accept four arguments: source, target, env and for_signature. source is a list of source nodes, target is a list of target nodes, env is the construction environment to use for context, and for_signature is a Boolean value that tells the function if it is being called for the purpose of generating a build signature (as opposed to actually executing the command). Since the build signature is used for rebuild determination, the function should omit those elements that do not affect whether a rebuild should be triggered if for_signature is true.

    Example:

        def g(source, target, env, for_signature):
            return [["gcc", "-c", "-o"] + target + source]
        b = Builder(generator=g)

    The generator and action arguments must not both be used for the same Builder.

src_builder
    Specifies a builder to use when a source file name suffix does not match any of the suffixes of the builder. Using this argument produces a multi-stage builder.

single_source
    Specifies that this builder expects exactly one source file per call. Giving more than one source file without target files results in implicitly calling the builder multiple times (once for each source given). Giving multiple source files together with target files results in a UserError exception.

source_ext_match
    When the specified action argument is a dictionary, the default behavior when a builder is passed multiple source files is to make sure that the extensions of all the source files match. If it is legal for this builder to be called with a list of source files with different extensions, this check can be suppressed by setting source_ext_match to False or some other non-true value. In this case, scons will use the suffix of the first specified source file to select the appropriate action from the action dictionary.

    In the following example, the setting of source_ext_match prevents scons from exiting with an error due to the mismatched suffixes of foo.in and foo.extra.

        b = Builder(action={'.in': 'build $SOURCES > $TARGET'}, source_ext_match=False)
        env = Environment(BUILDERS={'MyBuild': b})
        env.MyBuild('foo.out', ['foo.in', 'foo.extra'])

env
    A construction environment that can be used to fetch source code using this Builder. (Note that this environment is not used for normal builds of normal target files, which use the environment that was used to call the Builder for the target file.)

        b = Builder(action="build < $SOURCE > $TARGET")
        env = Environment(BUILDERS={'MyBuild' : b})
        env.MyBuild('foo.out', 'foo.in', my_arg='xyzzy')

chdir
    A directory from which scons will execute the action(s) specified for this Builder. If the chdir argument is a string or a directory Node, scons will change to the specified directory. If the chdir is not a string or Node and is non-zero, then scons will change to the target file's directory.

    Note that scons will not automatically modify its expansion of construction variables like $TARGET and $SOURCE when using the chdir keyword argument--that is, the expanded file names will still be relative to the project top directory, and consequently incorrect relative to the chdir directory. Builders created using chdir keyword argument, will need to use construction variable expansions like ${TARGET.file} and ${SOURCE.file} to use just the filename portion of the targets and source.

        b = Builder(action="build < ${SOURCE.file} > ${TARGET.file}", chdir=True)
        env = Environment(BUILDERS={'MyBuild' : b})
        env.MyBuild('sub/dir/foo.out', 'sub/dir/foo.in')

        Warning
        Python only keeps one current directory location even if there are multiple threads. This means that use of the chdir argument will not work with the SCons -j option, because individual worker threads spawned by SCons interfere with each other when they start changing directory.

Any additional keyword arguments supplied when a Builder object is created (that is, when the Builder function is called) will be set in the executing construction environment when the Builder object is called. The canonical example here would be to set a construction variable to the repository of a source code system.

Any such keyword arguments supplied when a Builder object is called will only be associated with the target created by that particular Builder call (and any other files built as a result of the call). These extra keyword arguments are passed to the following functions: command generator functions, function Actions, and emitter functions.

  Action Objects

The Builder factory function will turn its action keyword argument into an appropriate internal Action object, as will the Command function. You can also explicitly create Action objects for passing to Builder, or other functions that take actions as arguments, by calling the Action factory function. This may more efficient when multiple Builder objects need to do the same thing rather than letting each of those Builder objects create a separate Action object. It also allows more flexible configuration of an Action object. For example, to control the message printed when the action is taken you need to create the action object using Action.

The Action factory function returns an appropriate object for the action represented by the type of the action argument (the first positional parameter):

    • If action is already an Action object, the object is simply returned.

    • If action is a string, a command-line Action is returned. If such a string begins with @, the command line is not printed. If the string begins with hyphen (-), the exit status from the specified command is ignored, allowing execution to continue even if the command reports failure:

        Action('$CC -c -o $TARGET $SOURCES')
        # Doesn't print the line being executed.
        Action('@build $TARGET $SOURCES')
        # Ignores return value
        Action('-build $TARGET $SOURCES')

    • If action is a list, then a list of Action objects is returned. An Action object is created as necessary for each element in the list. If an element within the list is itself a list, the embedded list is taken as the command and arguments to be executed via the command line. This allows white space to be enclosed in an argument rather than taken as a separator by defining a command in a list within a list:

        Action([['cc', '-c', '-DWHITE SPACE', '-o', '$TARGET', '$SOURCES']])

    • If action is a callable object, a Function Action is returned. The callable must accept three keyword arguments: target, source and env. target is a Node object representing the target file, source is a Node object representing the source file and env is the construction environment used for building the target file.

    The target and source arguments may be lists of Node objects if there is more than one target file or source file. The actual target and source file name(s) may be retrieved from their Node objects via the built-in Python str function:

        target_file_name = str(target)
        source_file_names = [str(x) for x in source]

    The function should return 0 or None to indicate a successful build of the target file(s). The function may raise an exception or return a non-zero exit status to indicate an unsuccessful build.

        def build_it(target=None, source=None, env=None):
            # build the target from the source
            return 0
        a = Action(build_it)

    • If action is not one of the above types, no action object is generated and Action returns None.

The environment method form env.Action will expand construction variables in any argument strings, including action, at the time it is called, using the construction variables in the construction environment through which it was called. The global function form Action delays variable expansion until the Action object is actually used.

The optional second argument to Action is used to control the output which is printed when the Action is actually performed. If this parameter is omitted, or if the value is an empty string, a default output depending on the type of the action is used. For example, a command-line action will print the executed command. The following argument types are accepted:

    • If the second argument is a string, or if the cmdstr keyword argument is supplied, the string defines what is printed. Substitution is performed on the string before it is printed. The string typically contains substitutable variables, notably $TARGET(S) and $SOURCE(S), or consists of just a single variable which is optionally defined somewhere else. SCons itself heavily uses the latter variant.

    • If the second argument is a function, or if the strfunction keyword argument is supplied, the function will be called to obtain the string to be printed when the action is performed. The function must accept three keyword arguments: target, source and env, with the same interpretation as for a callable action argument above. The function is responsible for handling any required substitutions.

    • If the second argument is None, or if cmdstr=None is supplied, output is suppressed entirely.

The cmdstr and strfunction keyword arguments may not both be supplied in a single call to Action

Printing of action strings is affected by the setting of $PRINT_CMD_LINE_FUNC.

Examples:

    def build_it(target, source, env):
        # build the target from the source
        return 0
    def string_it(target, source, env):
        return "building '%s' from '%s'" % (target[0], source[0])
    # Use a positional argument.
    f = Action(build_it, string_it)
    s = Action(build_it, "building '$TARGET' from '$SOURCE'")
    # Alternatively, use a keyword argument.
    f = Action(build_it, strfunction=string_it)
    s = Action(build_it, cmdstr="building '$TARGET' from '$SOURCE'")
    # You can provide a configurable variable.
    l = Action(build_it, '$STRINGIT')

Any additional positional arguments, if present, may either be construction variables or lists of construction variables whose values will be included in the signature of the Action (the build signature) when deciding whether a target should be rebuilt because the action changed. Such variables may also be specified using the varlist keyword parameter; both positional and keyword forms may be present, and will be combined. This is necessary whenever you want a target to be rebuilt when a specific construction variable changes. This is not often needed for a string action, as the expanded variables will normally be part of the command line, but may be needed if a Python function action uses the value of a construction variable when generating the command line.

    def build_it(target, source, env):
        # build the target from the 'XXX' construction variable
        with open(target[0], 'w') as f:
            f.write(env['XXX'])
        return 0
    # Use positional arguments.
    a = Action(build_it, '$STRINGIT', ['XXX'])
    # Alternatively, use a keyword argument.
    a = Action(build_it, varlist=['XXX'])

The Action factory function can be passed the following optional keyword arguments to modify the Action object's behavior:

chdir
    If chdir is true (the default is False), SCons will change directories before executing the action. If the value of chdir is a string or a directory Node, SCons will change to the specified directory. Otherwise, if chdir evaluates true, SCons will change to the target file's directory.

    Note that SCons will not automatically modify its expansion of construction variables like $TARGET and $SOURCE when using the chdir parameter - that is, the expanded file names will still be relative to the project top directory, and consequently incorrect relative to the chdir directory. Builders created using chdir keyword argument, will need to use construction variable expansions like ${TARGET.file} and ${SOURCE.file} to use just the filename portion of the targets and source. Example:

        a = Action("build < ${SOURCE.file} > ${TARGET.file}", chdir=True)

exitstatfunc
    If provided, must be a callable which accepts a single parameter, the exit status (or return value) from the specified action, and which returns an arbitrary or modified value. This can be used, for example, to specify that an Action object's return value should be ignored under special conditions and SCons should, therefore, consider that the action always succeeds. Example:

        def always_succeed(s):
            # Always return 0, which indicates success.
            return 0
        a = Action("build < ${SOURCE.file} > ${TARGET.file}", exitstatfunc=always_succeed)

batch_key
    If provided, indicates that the Action can create multiple target files by processing multiple independent source files simultaneously. (The canonical example is "batch compilation" of multiple object files by passing multiple source files to a single invocation of a compiler such as Microsoft Visual C++. If the batch_key argument evaluates True and is not a callable object, the configured Action object will cause scons to collect all targets built with the Action object and configured with the same construction environment into single invocations of the Action object's command line or function. Command lines will typically want to use the $CHANGED_SOURCES construction variable (and possibly $CHANGED_TARGETS as well) to only pass to the command line those sources that have actually changed since their targets were built. Example:

        a = Action('build $CHANGED_SOURCES', batch_key=True)

    The batch_key argument may also be a callable function that returns a key that will be used to identify different "batches" of target files to be collected for batch building. A batch_key function must accept four parameters: action, env, target and source. The first parameter, action, is the active action object. The second parameter, env, is the construction environment configured for the target. The target and source parameters are the lists of targets and sources for the configured action.

    The returned key should typically be a tuple of values derived from the arguments, using any appropriate logic to decide how multiple invocations should be batched. For example, a batch_key function may decide to return the value of a specific construction variable from env which will cause scons to batch-build targets with matching values of that construction variable, or perhaps return the Python id() of the entire construction environment, in which case scons will batch-build all targets configured with the same construction environment. Returning None indicates that the particular target should not be part of any batched build, but instead will be built by a separate invocation of action's command or function. Example:

        def batch_key(action, env, target, source):
            tdir = target[0].dir
            if tdir.name == 'special':
                # Don't batch-build any target
                # in the special/ subdirectory.
                return None
            return (id(action), id(env), tdir)
        a = Action('build $CHANGED_SOURCES', batch_key=batch_key)

Miscellaneous Action Functions

    SCons supplies Action functions that arrange for various common file and directory manipulations to be performed. These are similar in concept to "tasks" in the Ant build tool, although the implementation is slightly different. These functions do not actually perform the specified action at the time the function is called, but rather are factory functions which return an Action object that can be executed at the appropriate time.

    There are two natural ways that these Action Functions are intended to be used.

    First, if you need to perform the action at the time the SConscript file is being read, you can use the Execute global function:

        Execute(Touch('file'))

    Second, you can use these functions to supply Actions in a list for use by the env.Command method. This can allow you to perform more complicated sequences of file manipulation without relying on platform-specific external commands:

        env = Environment(TMPBUILD='/tmp/builddir')
        env.Command(
            target='foo.out',
            source='foo.in',
            action=[
                Mkdir('$TMPBUILD'),
                Copy('$TMPBUILD', '${SOURCE.dir}'),
                "cd $TMPBUILD && make",
                Delete('$TMPBUILD'),
            ],
        )

    Chmod(dest, mode)
        Returns an Action object that changes the permissions on the specified dest file or directory to the specified mode which can be octal or string, similar to the POSIX chmod command. Examples:

            Execute(Chmod('file', 0o755))
            env.Command(
                'foo.out',
                'foo.in',
                [Copy('$TARGET', '$SOURCE'), Chmod('$TARGET', 0o755)],
            )
            Execute(Chmod('file', "ugo+w"))
            env.Command(
                'foo.out',
                'foo.in',
                [Copy('$TARGET', '$SOURCE'), Chmod('$TARGET', "ugo+w")],
            )

        The behavior of Chmod is limited on Windows and on WebAssembly platforms, see the notes in the Python documentation for os.chmod[9], which is the underlying function.

    Copy(dest, src)
        Returns an Action object that will copy the src source file or directory to the dest destination file or directory. If src is a list, dest must be a directory if it already exists. Examples:

            Execute(Copy('foo.output', 'foo.input'))
            env.Command('bar.out', 'bar.in', Copy('$TARGET', '$SOURCE'))

    Delete(entry, [must_exist])
        Returns an Action that deletes the specified entry, which may be a file or a directory tree. If a directory is specified, the entire directory tree will be removed. If the must_exist flag is set to a true value, then a Python error will be raised if the specified entry does not exist; the default is false, that is, the Action will silently do nothing if the entry does not exist. Examples:

            Execute(Delete('/tmp/buildroot'))
            env.Command(
                'foo.out',
                'foo.in',
                action=[
                    Delete('${TARGET.dir}'),
                    MyBuildAction,
                ],
            )
            Execute(Delete('file_that_must_exist', must_exist=True))

    Mkdir(name)
        Returns an Action that creates the directory name and all needed intermediate directories. name may also be a list of directories to create. Examples:

            Execute(Mkdir('/tmp/outputdir'))
            env.Command(
                'foo.out',
                'foo.in',
                action=[
                    Mkdir('/tmp/builddir'),
                    Copy('/tmp/builddir/foo.in', '$SOURCE'),
                    "cd /tmp/builddir && make",
                    Copy('$TARGET', '/tmp/builddir/foo.out'),
                ],
            )

    Move(dest, src)
        Returns an Action that moves the specified src file or directory to the specified dest file or directory. Examples:

            Execute(Move('file.destination', 'file.source'))
            env.Command(
                'output_file',
                'input_file',
                action=[MyBuildAction, Move('$TARGET', 'file_created_by_MyBuildAction')],
            )

    Touch(file)
        Returns an Action that updates the modification time on the specified file. Examples:

            Execute(Touch('file_to_be_touched'))
            env.Command('marker', 'input_file', action=[MyBuildAction, Touch('$TARGET')])

Variable Substitution

    Before executing a command, scons performs parameter expansion (substitution) on the string that makes up the action part of the builder. The format of a substitutable parameter is ${expression}. If expression refers to a variable, the braces in ${expression} can be omitted unless the variable name is immediately followed by a character that could either be interpreted as part of the name, or is Python syntax such as [ (for indexing/slicing) or . (for attribute access - see Special Attributes below).

    If expression refers to a construction variable, it (including the $ or ${ }) is replaced with the value of that variable in the construction environment at the time of execution. If expression looks like a variable name but is not defined in the construction environment it is replaced with an empty string. If expression refers to one of the Special Variables (see below) the corresponding value of the variable is substituted. expression may also be a Python expression to be evaluated. See Python Code Substitution below for a description.

    SCons uses the following rules when converting construction variables into command line strings:

        • If the value is a string it is interpreted as space delimited command line arguments.

        • If the value is a list it is interpreted as a list of command line arguments. Each element of the list is converted to a string.

        • Anything that is not a list or string is converted to a string and interpreted as a single command line argument.

        • Newline characters (\n) delimit lines. The newline parsing is done after all other parsing, so it is not possible for arguments (e.g. file names) to contain embedded newline characters.

        • For a literal $ use $$. For example, $$FOO will be left in the final string as $FOO.

    When a build action is executed, a hash of the command line is saved, together with other information about the target(s) built by the action, for future use in rebuild determination. This is called the build signature (or build action signature). The escape sequence $( subexpression $) may be used to indicate parts of a command line that may change without causing a rebuild--that is, which are not to be included when calculating the build signature. All text from $( up to and including the matching $) will be removed from the command line before it is added to the build signature while only the $( and $) will be removed before the command is executed. For example, the command line string:

        "echo Last build occurred $( $TODAY $). > $TARGET"

    would execute the command:

        echo Last build occurred $TODAY. > $TARGET

    but the build signature added to any target files would be computed from:

        echo Last build occurred  . > $TARGET

    While construction variables are normally directly substituted, if a construction variable has a value which is a callable Python object (a function, or a class with a __call__ method), that object is called during substitution. The callable must accept four arguments: target, source, env and for_signature. source is a list of source nodes, target is a list of target nodes, env is the construction environment to use for context, and for_signature is a boolean value that tells the callable if it is being called for the purpose of generating a build signature. Since the build signature is used for rebuild determination, variable elements that do not affect whether a rebuild should be triggered should be omitted from the returned string if for_signature is true. See $( and $) above for the syntax.

    SCons will insert whatever the callable returns into the expanded string:

        def foo(target, source, env, for_signature):
            return "bar"
        # Will expand $BAR to "bar baz"
        env = Environment(FOO=foo, BAR="$FOO baz")

    As a reminder, substitution happens when $BAR is actually used in a builder action. The value of env['BAR'] will be exactly as it was set: "$FOO baz". This can make debugging tricky, as the substituted result is not available at the time the SConscript files are being interpreted and thus not available to the print function. However, you can perform the substitution on demand by calling the env.subst method for this purpose.

    You can use this feature to pass arguments to a callable variable by creating a callable class that stores passed arguments in the instance, and then uses them (in the __call__ method) when the instance is called. Note that in this case, the entire variable expansion must be enclosed by curly braces so that the arguments will be associated with the instantiation of the class:

        class foo:
            def __init__(self, arg):
                self.arg = arg
            def __call__(self, target, source, env, for_signature):
                return self.arg + " bar"
        # Will expand $BAR to "my argument bar baz"
        env=Environment(FOO=foo, BAR="${FOO('my argument')} baz")

Substitution: Special Variables

    Besides regular construction variables, scons provides the following Special Variables for use in expanding commands:

    $CHANGED_SOURCES
        The file names of all sources of the build command that have changed since the target was last built.

    $CHANGED_TARGETS
        The file names of all targets that would be built from sources that have changed since the target was last built.

    $SOURCE
        The file name of the source of the build command, or the file name of the first source if multiple sources are being built.

    $SOURCES
        The file names of the sources of the build command.

    $TARGET
        The file name of the target being built, or the file name of the first target if multiple targets are being built.

    $TARGETS
        The file names of all targets being built.

    $UNCHANGED_SOURCES
        The file names of all sources of the build command that have not changed since the target was last built.

    $UNCHANGED_TARGETS
        The file names of all targets that would be built from sources that have not changed since the target was last built.

    These names are reserved and may not be assigned to or used as construction variables. SCons computes them in a context-dependent manner and they and are not retrieved from a construction environment.

    For example, the following builder call:

        env = Environment(CC='cc')
        env.Command(
            target=['foo'],
            source=['foo.c', 'bar.c'],
            action='@echo $CC -c -o $TARGET $SOURCES'
        )

    would produce the following output:

        cc -c -o foo foo.c bar.c

    In the previous example, a string ${SOURCES[1]} would expand to: bar.c.

Substitution: Special Attributes

    A variable name may have the following modifiers appended within the enclosing curly braces to access properties of the interpolated string. These are known as special attributes.
        base -
            The base path of the file name,
            including the directory path
            but excluding any suffix.

        dir - The name of the directory in which the file exists.
        file - The file name, minus any directory portion.
        filebase - Like file but minus its suffix.
        suffix - Just the file suffix.
        abspath - The absolute path name of the file.
        relpath - The path name of the file relative to the project top directory.
        posix -
            The path with directories separated by forward slashes
            (/).
            Sometimes necessary on Windows systems
            when a path references a file on other (POSIX) systems.

        windows -
            The path with directories separated by backslashes
            (\\).
            Sometimes necessary on POSIX-style systems
            when a path references a file on other (Windows) systems.
            win32 is a (deprecated) synonym for
            windows.

        srcpath -
            The directory and file name to the source file linked to this file through
            VariantDir().
            If this file isn't linked,
            it just returns the directory and filename unchanged.

        srcdir -
            The directory containing the source file linked to this file through
            VariantDir().
            If this file isn't linked,
            it just returns the directory part of the filename.

        rsrcpath -
            The directory and file name to the source file linked to this file through
            VariantDir().
            If the file does not exist locally but exists in a Repository,
            the path in the Repository is returned.
            If this file isn't linked, it just returns the
            directory and filename unchanged.

        rsrcdir -
            The Repository directory containing the source file linked to this file through
            VariantDir().
            If this file isn't linked,
            it just returns the directory part of the filename.

    For example, the specified target will expand as follows for the corresponding modifiers:

        $TARGET              => sub/dir/file.x
        ${TARGET.base}       => sub/dir/file
        ${TARGET.dir}        => sub/dir
        ${TARGET.file}       => file.x
        ${TARGET.filebase}   => file
        ${TARGET.suffix}     => .x
        ${TARGET.abspath}    => /top/dir/sub/dir/file.x
        ${TARGET.relpath}    => sub/dir/file.x
        $TARGET              => ../dir2/file.x
        ${TARGET.abspath}    => /top/dir2/file.x
        ${TARGET.relpath}    => ../dir2/file.x
        SConscript('src/SConscript', variant_dir='sub/dir')
        $SOURCE              => sub/dir/file.x
        ${SOURCE.srcpath}    => src/file.x
        ${SOURCE.srcdir}     => src
        Repository('/usr/repository')
        $SOURCE              => sub/dir/file.x
        ${SOURCE.rsrcpath}   => /usr/repository/src/file.x
        ${SOURCE.rsrcdir}    => /usr/repository/src

    Some modifiers can be combined, like ${TARGET.srcpath.base), ${TARGET.file.suffix}, etc.

Python Code Substitution

    If a substitutable expression using the notation ${expression} does not appear to match one of the other substitution patterns, it is evaluated as a Python expression. This uses Python's eval function, with the globals parameter set to the current environment's set of construction variables, and the result substituted in. So in the following case:

        env.Command(
            'foo.out', 'foo.in', "echo ${COND==1 and 'FOO' or 'BAR'} > $TARGET"
        )

    the command executed will be either

        echo FOO > foo.out

    or

        echo BAR > foo.out

    according to the current value of env['COND'] when the command is executed. The evaluation takes place when the target is being built, not when the SConscript is being read. So if env['COND'] is changed later in the SConscript, the final value will be used.

    Here's a more complete example. Note that all of COND, FOO, and BAR are construction variables, and their values are substituted into the final command. FOO is a list, so its elements are interpolated separated by spaces.

        env=Environment()
        env['COND'] = 1
        env['FOO'] = ['foo1', 'foo2']
        env['BAR'] = 'barbar'
        env.Command(
            'foo.out', 'foo.in', "echo ${COND==1 and FOO or BAR} > $TARGET"
        )

    will execute:

        echo foo1 foo2 > foo.out

    In point of fact, Python expression evaluation is how the special attributes are substituted: they are simply attributes of the Python objects that represent $TARGET, $SOURCES, etc., which SCons passes to eval which returns the value.

        Caution

        Use of the Python eval function is considered to have security implications, since, depending on input sources, arbitrary unchecked strings of code can be executed by the Python interpreter. Although SCons makes use of it in a somewhat restricted context, you should be aware of this issue when using the ${python-expression-for-subst} form.

  Scanner Objects

Scanner objects are used to scan specific file types for implicit dependencies, for example embedded preprocessor/compiler directives that cause other files to be included during processing. SCons has a number of pre-built Scanner objects, so it is usually only necessary to set up Scanners for new file types. You do this by calling the Scanner factory function. Scanner accepts the following arguments. Only function is required; the rest are optional:

function
    A function which can process ("scan") a given Node (usually a file) and return a list of Nodes representing any implicit dependencies (usually files) which will be tracked for the Node. The function must accept three required arguments, node, env and path, and an optional fourth, arg. node is the internal SCons node representing the file to scan, env is the construction environment to use during the scan, and path is a tuple of directories that can be searched for files, as generated by the optional scanner path_function. If the argument parameter was supplied when the Scanner object was created, it is passed as the arg parameter to the scanner function when it is called. Since argument is optional, the scanner function may be called without an arg parameter.

    The scanner function can make use of str(node) to fetch the name of the file, node.dir to fetch the directory the file is in, node.get_contents() to fetch the contents of the file as bytes or node.get_text_contents() to fetch the contents of the file as text.

    The scanner function should account for any directories listed in the path parameter when determining the existence of possible dependencies. External tools such as the C/C++ preprocessor are given lists of directories to search for source file inclusion directives (e.g. #include "myheader.h"). That list is generated from the relevant path variable (e.g. $CPPPATH for C/C++). The Scanner can be directed to pass the same list on to the scanner function via the path parameter so it can search in the same places. The Scanner is enabled to pass this list via the path_function argument at Scanner creation time.

    Instead of a scanner function, you can supply a dictionary as the function parameter. The dictionary must map keys (such as file suffixes) to other Scanner objects. A Scanner created this way serves as a dispatcher: the Scanner's skeys parameter is automatically populated with the dictionary's keys, indicating that the Scanner handles Nodes which would be selected by those keys; the mapping is then used to pass the file on to a different Scanner that would not have been selected to handle that Node based on its own skeys.

    Note that the file to scan is not guaranteed to exist at the time the scanner is called - it could be a generated file which has not been generated yet - so the scanner function must be tolerant of that.

    While many scanner functions operate on source code files by looking for known patterns in the code, they can really do anything they need to. For example, the Program Builder is assigned a target_scanner which examines the list of libraries supplied for the build ($LIBS) and decides whether to add them as dependencies, it does not look inside the built binary.

    It is up to the scanner function to decide whether or not to generate an SCons dependency for candidates identified by scanning. Dependencies are a key part of SCons operation, enabling both rebuild determination and correct ordering of builds. It is particularly important that generated files which are dependencies are added into the Node graph, or use-before-create failures are likely. However, not everything may need to be tracked as a dependency. In some cases, implementation-provided header files change infrequently but are included very widely, so tracking them in the SCons node graph could become quite expensive for limited benefit - consider for example the C standard header file string.h. The scanner function is not passed any special information to help make this choice, so the decision making encoded in the scanner function must be carefully considered.

name
    The name to use for the Scanner. This is mainly used to identify the Scanner internally. The default value is "NONE".

argument
    If specified, will be passed to the scanner function function and the path function path_function when called, as the optional parameter each of those functions takes.

skeys
    Scanner key(s) indicating the file types this scanner is associated with. Used internally to select an appropriate scanner. In the usual case of scanning for file names, this argument will be a list of suffixes for the different file types that this Scanner knows how to scan. If skeys is a string, it will be expanded into a list by the current environment.

path_function
    If specified, a function to generate paths to pass to the scanner function to search while generating dependencies. The function must take five arguments: a construction environment, a Node for the directory containing the SConscript file in which the first target was defined, a list of target nodes, a list of source nodes, and the value of argument if it was supplied when the Scanner was created (since argument is optional, the function may be called without this argument, the path_function should be prepared for this). Must return a tuple of directories that can be searched for files to be returned by this Scanner object.

    The FindPathDirs function can be called to return a ready-made path_function for a given construction variable name, which is often easier than writing your own function from scratch. For example, path_function=FindPathDirs('CPPPATH') means the scanner function will be called with the paths extracted from $CPPPATH in the construction environment env, and passed as the path parameter to the scanner function.

node_class
    The class of Node that should be returned by this Scanner object. Any strings or other objects returned by the scanner function that are not of this class will be run through the function supplied by the node_factory argument. A value of None can be supplied to indicate no conversion; the default is to return File nodes.

node_factory
    A Python function that will take a string or other object and turn it into the appropriate class of Node to be returned by this Scanner object, as indicated by node_class.

scan_check
    A Python function that takes two arguments, a Node (file) and a construction environment, and returns whether the Node should, in fact, be scanned for dependencies. This check can be used to eliminate unnecessary calls to the scanner function when, for example, the underlying file represented by a Node does not yet exist.

recursive
    Specifies whether this scanner should be re-invoked on the dependency files returned by the scanner. If omitted, the Node subsystem will only invoke the scanner on the file being scanned and not recurse. Recursion is needed when the files returned by the scanner may themselves contain further file dependencies, as in the case of preprocessor #include lines. A value that evaluates true enables recursion; recursive may be a callable function, in which case it will be called with a list of Nodes found and should return a list of Nodes that should be scanned recursively; this can be used to select a specific subset of Nodes for additional scanning.

Once created, a Scanner can added to an environment by setting it in the $SCANNERS list, which automatically triggers SCons to also add it to the environment as a method. However, usually a scanner is not truly standalone, but needs to be plugged in to the existing selection mechanism for deciding how to scan source files based on filename extensions. For this, SCons has a global SourceFileScanner object that is used by the Object, SharedObject and StaticObject builders to decide which scanner should be used. You can use the SourceFileScanner.add_scanner() method to add your own Scanner object to the SCons infrastructure that builds target programs or libraries from a list of source files of different types:

    def xyz_scan(node, env, path):
        contents = node.get_text_contents()
        # Scan the contents and return the included files.
    XYZScanner = Scanner(xyz_scan)
    SourceFileScanner.add_scanner('.xyz', XYZScanner)
    env.Program('my_prog', ['file1.c', 'file2.f', 'file3.xyz'])

  Tool Modules

Custom tools can be added to a project either by placing them in the site_tools subdirectory of a configured site directory, or in a location specified by the toolpath keyword argument to Environment. You have to arrange to call a tool to put it into effect, either as part of the list given to the tools keyword argument at construction environment initialization, or by calling env.Tool.

The toolpath parameter takes a list of path strings, and the tools parameter takes a list of tools, which are often strings:

    env = Environment(tools=['default', 'foo'], toolpath=['tools'])

This looks for a tool specification module foo in directory tools and in the standard locations, as well as using the ordinary default tools for the platform.

When looking up tool specification modules, directories specified via toolpath are considered before the existing tool path (site_tools subdirectories of the default or specified site directories), which are in turn considered before built-in tools. For example, adding a tool specification module gcc.py to the toolpath directory would override the built-in gcc tool. The toolpath is saved in the environment and will be used by subsequent calls to the env.Tool method, as well as by env.Clone.

    base = Environment(toolpath=['custom_path'])
    derived = base.Clone(tools=['custom_tool'])
    derived.CustomBuilder()

A tool specification module is a form of Python module, looked up internally using the Python import mechanism, so a tool can consist either of a single Python file taking the name of the tool (e.g. mytool.py) or a directory taking the name of the tool (e.g. mytool/) which contains at least an __init__.py file. A tool specification module has two required entry points:

generate(env, **kwargs)
    Modify the construction environment env to set up necessary construction variables, Builders, Emitters, etc., so the facilities represented by the tool can be executed. Take care not to overwrite construction variables which may have been explicitly set by the user; retain and/or append instead. For example:

        def generate(env):
            ...
            if 'MYTOOL' not in env:
                env['MYTOOL'] = env.Detect("mytool")
            flags = env.get('MYTOOLFLAGS', SCons.Util.CLVar())
            env.AppendUnique(MYTOOLFLAGS='--myarg')
            ...

    The generate function may use any keyword arguments that the user supplies via kwargs to vary its initialization.

exists(env)
    Return a truthy value if the tool can be called in the context of env, else return a falsy value. Usually this means looking up one or more known programs using the PATH from the supplied env, but the tool can make the exists decision in any way it chooses.

    Note

    At the moment, user-added tools do not automatically have their exists function called. As a result, it is recommended that the generate function be defensively coded - that is, do not rely on any necessary existence checks already having been performed. This is expected to be a temporary limitation, and the exists function should still be provided.

An element of the tools list may also be a function or other callable object (including a Tool object returned by a previous call to Tool) in which case the Environment function will directly call that object to update the new construction environment. No tool lookup is done in this case.

    def my_tool(env):
        env['XYZZY'] = 'xyzzy'
    env = Environment(tools=[my_tool])

An element of the tools list may also be a two-element list or tuple of the form (toolname, kw_dict). SCons searches for the a tool specification module toolname as described above, and passes kw_dict, which must be a dictionary, as keyword arguments to the tool's generate function. The generate function can use those arguments to modify the tool's behavior by setting up the environment in different ways or otherwise changing its initialization.

    # in tools/my_tool.py:
    def generate(env, **kwargs):
        # Sets MY_TOOL to the value of keyword 'arg1' or '1' if not supplied
        env['MY_TOOL'] = kwargs.get('arg1', '1')
    def exists(env):
        return True
    # in SConstruct:
    env = Environment(
        tools=['default', ('my_tool', {'arg1': 'abc'})], toolpath=['tools']
    )

The tool specification (my_tool in the example) can use the $PLATFORM variable from the construction environment it is passed to customize the tool for different platforms.

Tools can be "nested" - that is, they can be located within a subdirectory in the toolpath. A nested tool name uses a dot to represent a directory separator

    # namespaced builder
    env = Environment(ENV=os.environ.copy(), tools=['SubDir1.SubDir2.SomeTool'])
    env.SomeTool(targets, sources)
    # Search Paths
    # SCons\Tool\SubDir1\SubDir2\SomeTool.py
    # SCons\Tool\SubDir1\SubDir2\SomeTool\__init__.py
    # .\site_scons\site_tools\SubDir1\SubDir2\SomeTool.py
    # .\site_scons\site_tools\SubDir1\SubDir2\SomeTool\__init__.py

SYSTEM-SPECIFIC BEHAVIOR

scons and its configuration files are very portable, due largely to its implementation in Python. There are, however, a few portability issues waiting to trap the unwary.

  .C File Suffix

scons handles the upper-case .C file suffix differently, depending on the capabilities of the underlying system. On a case-sensitive system such as Linux or UNIX, scons treats a file with a .C suffix as a C++ source file. On a case-insensitive system such as Windows, scons treats a file with a .C suffix as a C source file.

  Fortran File Suffixes

There are several ways source file suffixes impact the behavior of SCons when working with Fortran language code (not all are system-specific, but they are included here for completeness).

As the Fortran language has evolved through multiple standards editions, projects might have a need to handle files from different language generations differently. To this end, SCons dispatches to a different compiler dialect setup (expressed as a set of construction variables) depending on the file suffix. By default, all of these setups start out the same, but individual construction variables can be modified as needed to tune a given dialect. Each of these dialacts has a tool specification module whose documentation describes the construction variables associated with that dialect: .f (as well as .for and .ftn) in fortran; (construction variables start with FORTRAN) .f77 in f77; (construction variables start with F77) .f90 in f90; (construction variables start with F90) .f95 in f95; (construction variables start with F95) .f03 in f03; (construction variables start with F03) .f08 in f08 (construction variables start with F08).

While SCons recognizes multiple internal dialects based on filename suffixes, the convention of various available Fortran compilers is to assign an actual meaning to only two of these suffixes: .f (as well as .for and .ftn) refers to the fixed-format source code that was the only available option in FORTRAN 77 and earlier, and .f90 refers to free-format source code which became available as of the Fortran 90 standard. Some compilers recognize suffixes which correspond to Fortran specifications later then F90 as equivalent to .f90 for this purpose, while some do not - check the documentation for your compiler. An occasionally suggested policy suggestion is to use only .f and .f90 as Fortran filename suffixes. The fixed/free form determination can usually be controlled explicitly with compiler flags (e.g. -ffixed-form for gfortran), overriding any assumption that may be made based on the source file suffix.

The source file suffix does not imply conformance with the similarly-named Fortran standard - a suffix of .f08 does not mean you are compiling specifically for Fortran 2008. Normally, compilers provide command-line options for making this selection (e.g. -std=f2008 for gfortran).

For dialects from F90 on (including the generic FORTRAN dialect), a suffix of .mod is recognized for Fortran modules. These files are a side effect of compiling a Fortran source file containing module declarations, and must be available when other code which declares that it uses the module is processed. SCons does not currently have integrated support for submodules, introduced in the Fortran 2008 standard - the invoked compiler will produce results, but SCons will not recognize .smod files as tracked objects.

On a case-sensitive system such as Linux or UNIX, a file with a an upper-cased suffix from the set .F, .FOR, .FTN, .F90, .F95, .F03 and .F08 is treated as a Fortran source file which shall first be run through the standard C preprocessor. The lower-cased versions of these suffixes do not trigger this behavior. On systems which do not distinguish between uppper and lower case in filenames, this behavior is not available, but files suffixed with either .FPP or .fpp are always passed to the preprocessor first. This matches the convention of gfortran from the GNU Compiler Collection, and also followed by certain other Fortran compilers. For these two suffixes, the generic FORTRAN dialect will be selected.

SCons itself does not invoke the preprocessor, that is handled by the compiler, but it adds construction variables which are applicable to the preprocessor run. You can see this difference by examining $FORTRANPPCOM and $FORTRANPPCOMSTR which are used instead of $FORTRANCOM and $FORTRANCOMSTR for that dialect.

  Windows: Cygwin Tools and Cygwin Python vs. Windows Pythons

Cygwin supplies a set of tools and utilities that let users work on a Windows system using a POSIX-like environment. The Cygwin tools, including Cygwin Python, do this, in part, by sharing an ability to interpret POSIX-style path names. For example, the Cygwin tools will internally translate a Cygwin path name like /cygdrive/c/mydir to an equivalent Windows pathname of C:/mydir (equivalent to C:\mydir).

Versions of Python that are built for native Windows execution, such as the python.org and ActiveState versions, do not understand the Cygwin path name semantics. This means that using a native Windows version of Python to build compiled programs using Cygwin tools (such as gcc, bison and flex) may yield unpredictable results. "Mixing and matching" in this way can be made to work, but it requires careful attention to the use of path names in your SConscript files.

In practice, users can sidestep the issue by adopting the following guidelines: When using Cygwin's gcc for compiling, use the Cygwin-supplied Python interpreter to run scons; when using Microsoft Visual C++ (or some other "native" Windows compiler) use the python.org, Microsoft Store, ActiveState or other native version of Python to run scons.

This discussion largely applies to the msys2 environment as well (with the use of the mingw compiler toolchain), in particular the recommendation to use the msys2 version of Python if running scons from inside an msys2 shell.

  Windows: scons.bat file

On Windows, if scons is executed via a wrapper scons.bat batch file, there are (at least) two ramifications. Note this is no longer the default - scons installed via Python''s pip installer will have an scons.exe which does not have these limitations:

First, Windows command-line users that want to use variable assignment on the command line may have to put double quotes around the assignments, otherwise the Windows command shell will consume those as arguments to itself, not to scons:

    scons "FOO=BAR" "BAZ=BLEH"

Second, the Cygwin shell does not recognize typing scons at the command line prompt as referring to this wrapper. You can work around this either by executing scons.bat (including the extension) from the Cygwin command line, or by creating a wrapper shell script named scons which invokes scons.bat.

  MinGW

The MinGW bin directory must be in your PATH environment variable or the ['ENV']['PATH'] construction variable for scons to detect and use the MinGW tools. When running under the native Windows Python interpreter, scons will prefer the MinGW tools over the Cygwin tools, if they are both installed, regardless of the order of the bin directories in the PATH variable. If you have both MSVC and MinGW installed and you want to use MinGW instead of MSVC, then you must explicitly tell scons to use MinGW by passing tools=['mingw'] to the Environment function, because scons will prefer the MSVC tools over the MinGW tools.

ENVIRONMENT

In general, scons is not controlled by environment variables set in the shell used to invoke it, leaving it up to the SConscript file author to import those if desired. However the following variables are imported by scons itself if set:

SCONS_LIB_DIR
    Specifies the directory that contains the scons Python module directory. Normally scons can deduce this, but in some circumstances, such as working with a source release, it may be necessary to specify (for example, /home/aroach/scons-src-0.01/src/engine).

SCONSFLAGS
    A string containing options that will be used by scons in addition to those passed on the command line. Can be used to reduce frequent retyping of common options. The contents of SCONSFLAGS are considered before any passed command line options, so the command line can be used to override SCONSFLAGS options if necessary.

SCONS_CACHE_MSVC_CONFIG
    (Windows only). If set, save the shell environment variables generated when setting up the Microsoft Visual C++ compiler (and/or Build Tools) to a cache file, to give these settings persistence across scons invocations. Generating this information is relatively expensive, so using this option may aid performance where scons is run often, such as Continuous Integration setups.

    If set to a True-like value ("1", "true" or "True") will cache to a file named scons_msvc_cache.json in the user's home directory. If set to a pathname, will use that pathname for the cache.

    Note: this implementation may still be somewhat fragile. In case of problems, remove the cache file - recreating with fresh info normally resolves any issues. SCons ignores failures reading or writing the cache file and will silently revert to non-cached behavior in such cases.

    New in 3.1 (experimental). The default cache file name was changed to its present value in 4.4, and contents were expanded.

QTDIR
    If using the qt tool, this is the path to the Qt installation to build against. SCons respects this setting because it is a long-standing convention in the Qt world, where multiple Qt installations are possible.

SEE ALSO
        The SCons User Guide at
        https://scons.org/doc/production/HTML/scons-user.html

    The SCons Design Document (old)
        The SCons Cookbook at
        https://scons-cookbook.readthedocs.io
        for examples of how to solve various problems with SCons.

        SCons source code
        on GitHub[10]

        The SCons API Reference
        https://scons.org/doc/production/HTML/scons-api/index.html
        (for internal details)

AUTHORS

Originally: Steven Knight knight@baldmt.com and Anthony Roach aroach@electriceyeball.com.

Since 2010: The SCons Development Team scons-dev@scons.org.

AUTHOR

The SCons Development Team

COPYRIGHT
Copyright © 2001 - 2024 The SCons Foundation

NOTES

1.  https://github.com/SCons/scons-contrib
    https://github.com/SCons/scons-contrib

2.  LLVM specification
    https://clang.llvm.org/docs/JSONCompilationDatabase.html

3.  JEP 313
    https:openjdk.java.net/jeps/313

4.  https://learn.microsoft.com/en-us/cpp/build/reference/vcxproj-file-structure
    https://learn.microsoft.com/en-us/cpp/build/reference/vcxproj-file-structure

5.  https://learn.microsoft.com/en-us/visualstudio/extensibility/internals/solution-dot-sln-file
    https://learn.microsoft.com/en-us/visualstudio/extensibility/internals/solution-dot-sln-file

6.  optparse documentation
    https://docs.python.org/3/library/optparse.html

7.  If no_progress is set via SetOption in an SConscript file (but not if set in a site_init.py file) there will still be an initial status message about reading SConscript files since SCons has to start reading them before it can see the SetOption.

8.  http://www.opensource.org/licenses/alphabetical
    http://www.opensource.org/licenses/alphabetical

9.  os.chmod
    https://docs.python.org/3/library/os.html#os.chmod

10. on GitHub
    https://github.com/SCons/scons