GNU Binary Utilities: Selecting the Target System

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# 18. Selecting the Target System

You can specify two aspects of the target system to the GNU binary file utilities, each in several ways:

- the target

- the architecture

In the following summaries, the lists of ways to specify values are in order of decreasing precedence. The ways listed first override those listed later.

The commands to list valid values only list the values for which the programs you are running were configured. If they were configured with ``--enable-targets=all'`, the commands list most of the available values, but a few are left out; not all targets can be configured in at once because some of them can only be configured native (on hosts with the same type as the target system).

> 18.1 Target Selection |  |
> 18.2 Architecture Selection |  |

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## 18.1 Target Selection

A target is an object file format. A given target may be supported for multiple architectures (see section 18.2 Architecture Selection). A target selection may also have variations for different operating systems or architectures.

The command to list valid target values is ``objdump -i'` (the first column of output contains the relevant information).

Some sample values are: ``a.out-hp300bsd'`, ``ecoff-littlemips'`, ``a.out-sunos-big'`.

You can also specify a target using a configuration triplet. This is the same sort of name that is passed to ``configure'` to specify a target. When you use a configuration triplet as an argument, it must be fully canonicalized. You can see the canonical version of a triplet by running the shell script ``config.sub'` which is included with the sources.

Some sample configuration triplets are: ``m68k-hp-bsd'`, ``mips-dec-ultrix'`, ``sparc-sun-sunos'`.

### `objdump` Target

Ways to specify:

1. command line option: ``-b'` or ``--target'`

2. environment variable `GNUTARGET`

3. deduced from the input file

### `objcopy` and `strip` Input Target

Ways to specify:

1. command line options: ``-I'` or ``--input-target'`, or ``-F'` or ``--target'`

2. environment variable `GNUTARGET`

3. deduced from the input file

### `objcopy` and `strip` Output Target

Ways to specify:

1. command line options: ``-O'` or ``--output-target'`, or ``-F'` or ``--target'`

2. the input target (see "`objcopy` and `strip` Input Target" above)

3. environment variable `GNUTARGET`

4. deduced from the input file

### `nm`, `size`, and `strings` Target

Ways to specify:

1. command line option: ``--target'`

2. environment variable `GNUTARGET`

3. deduced from the input file

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## 18.2 Architecture Selection

An architecture is a type of CPU on which an object file is to run. Its name may contain a colon, separating the name of the processor family from the name of the particular CPU.

The command to list valid architecture values is ``objdump -i'` (the second column contains the relevant information).

Sample values: ``m68k:68020'`, ``mips:3000'`, ``sparc'`.

### `objdump` Architecture

Ways to specify:

1. command line option: ``-m'` or ``--architecture'`

2. deduced from the input file

### `objcopy`, `nm`, `size`, `strings` Architecture

Ways to specify:

1. deduced from the input file

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