virt-diff(1)

名前
virt-diff - Differences between files in two virtual machines

書式
 virt-diff [--options] -d domain1 -D domain2

 virt-diff [--options] -a disk1.img [-a ...] -A disk2.img [-A ...]

説明
"virt-diff" lists the differences between files in two virtual machines or disk images. The usual use case is to show the changes in a VM after it has been running for a while, by taking a snapshot, running the VM, and then using this tool to show what changed between the new VM state and the old snapshot.

This tool will find differences in filenames, file sizes, checksums, extended attributes, file content and more from a virtual machine or disk image. However it does not look at the boot loader, unused space between partitions or within filesystems, "hidden" sectors and so on. In other words, it is not a security or forensics tool.

To specify two guests, you have to use the -a or -d option(s) for the first guest, and the -A or -D option(s) for the second guest. The common case is:

 virt-diff -a old.img -A new.img

or using names known to libvirt:

 virt-diff -d oldguest -D newguest

オプション

--help
    簡単なヘルプを表示します。

-a file
--add file
    Add file which should be a disk image from the first virtual machine. If the virtual machine has multiple block devices, you must supply all of them with separate -a options.

    ディスクイメージの形式は自動検知されます。 これを上書きして強制的に特定の形式を使用する場合、 --format=.. オプションを使用します。

-a URI
--add URI
    リモートディスクを追加します。 "リモートストレージの追加" in guestfish(1) 参照。

--all
    Same as --extra-stats --times --uids --xattrs.

--atime
    The default is to ignore changes in file access times, since those are unlikely to be interesting. Using this flag shows atime differences as well.

-A file
-A URI
    Add a disk image from the second virtual machine.

--blocksize=512
--blocksize=4096
--blocksize
    This parameter sets the sector size of the disk image. It affects all explicitly added subsequent disks after this parameter. Using --blocksize with no argument switches the disk sector size to the default value which is usually 512 bytes. See also "guestfs_add_drive_opts" in guestfs(3).

--checksum
--checksum=crc|md5|sha1|sha224|sha256|sha384|sha512
    Use a checksum over file contents to detect when regular files have changed content.

    With no argument, this defaults to using md5. Using an argument, you can select the checksum type to use. If the flag is omitted then file times and size are used to determine if a file has changed.

-c URI
--connect URI
    libvirt を使用していると、指定された URI に接続します。 省略すると、デフォルトの libvirt ハイパーバイザーに接続します。

    ゲストのブロックデバイスを直接指定していると（(-a)）、libvirt は何も使用されません。

--csv
    Write out the results in CSV format (comma-separated values). This format can be imported easily into databases and spreadsheets, but read "NOTE ABOUT CSV FORMAT" below.

--dir-links
    The default is to ignore changes in the number of links in directory entries, since those are unlikely to be interesting. Using this flag shows changes to the nlink field of directories.

--dir-times
    The default is to ignore changed times on directory entries, since those are unlikely to be interesting. Using this flag shows changes to the time fields of directories.

-d guest
--domain guest
    Add all the disks from the named libvirt guest, as the first guest. Domain UUIDs can be used instead of names.

-D guest
    Add all the disks from the named libvirt guest, as the second guest. Domain UUIDs can be used instead of names.

--echo-keys
    When prompting for keys and passphrases, virt-diff normally turns echoing off so you cannot see what you are typing. If you are not worried about Tempest attacks and there is no one else in the room you can specify this flag to see what you are typing.

--extra-stats
    Display extra stats.

--format=raw|qcow2|..
--format
    The default for the -a/-A option is to auto-detect the format of the disk image. Using this forces the disk format for -a/-A options which follow on the command line. Using --format with no argument switches back to auto-detection for subsequent -a/-A options.

    例:

     virt-diff --format=raw -a disk.img [...]

    forces raw format (no auto-detection) for disk.img.

     virt-diff --format=raw -a disk.img --format -a another.img [...]

    forces raw format (no auto-detection) for disk.img and reverts to auto-detection for another.img.

    仮想マシンのディスクイメージが信頼できない raw 形式である場合、 ディスク形式を指定するためにこのオプションを使用すべきです。 これにより、悪意のある仮想マシンにより起こり得る セキュリティ問題を回避できます (CVE-2010-3851)。

-h
--human-readable
    読みやすい形式でファイル容量を表示します。

--key SELECTOR
    Specify a key for LUKS, to automatically open a LUKS device when using the inspection.

    --key NAME:key:KEY_STRING
    --key UUID:key:KEY_STRING
    --key all:key:KEY_STRING
        "NAME" is the libguestfs device name (eg. "/dev/sda1"). "UUID" is the device UUID. "all" means try the key against any encrypted device.

        Use the specified "KEY_STRING" as passphrase.

    --key NAME:file:FILENAME
    --key UUID:file:FILENAME
    --key all:file:FILENAME
        Read the passphrase from FILENAME.

    --key NAME:clevis
    --key UUID:clevis
    --key all:clevis
        Attempt passphrase-less unlocking for the device with Clevis, over the network. Please refer to "ENCRYPTED DISKS" in guestfs(3) for more information on network-bound disk encryption (NBDE).

        Note that if any such option is present on the command line, QEMU user networking will be automatically enabled for the libguestfs appliance.

--keys-from-stdin
    Read key or passphrase parameters from stdin. The default is to try to read passphrases from the user by opening /dev/tty.

    If there are multiple encrypted devices then you may need to supply multiple keys on stdin, one per line.

--times
    時間の項目を表示します。

--time-days
    Display time fields as days before now (negative if in the future).

    Note that 0 in output means "up to 1 day before now", or that the age of the file is between 0 and 86399 seconds.

--time-relative
    Display time fields as seconds before now (negative if in the future).

--time-t
    Display time fields as seconds since the Unix epoch.

--uids
    UID と GID の項目を表示します。

-v
--verbose
    デバッグ用の冗長なメッセージを有効にします。

-V
--version
    バージョン番号を表示して、終了します。

-x  libguestfs API 呼び出しのトレースを有効にします。

--xattrs
    Display extended attributes.

CSV 形式に関する注意
Comma-separated values (CSV) is a deceptive format. It seems like it should be easy to parse, but it is definitely not easy to parse.

神話: ただコンマで項目を区切る。 真実: これは正しく動き ません。この例は 2 つの列があります:

 "foo,bar",baz

神話: 同時にファイルの 1 行を読み込みます。 真実: これは正しく動き ません。この例は 1 つの行があります:

 "foo
 bar",baz

For shell scripts, use "csvtool" (https://github.com/Chris00/ocaml-csv also packaged in major Linux distributions).

For other languages, use a CSV processing library (eg. "Text::CSV" for Perl or Python’s built-in csv library).

Most spreadsheets and databases can import CSV directly.

終了ステータス
このプログラムは、成功すると 0 を、エラーがあると 0 以外を返します。

関連項目
guestfs(3), guestfish(1), virt-cat(1), virt-copy-out(1), virt-ls(1), virt-tar-out(1), http://libguestfs.org/.

著者
Richard W.M. Jones http://people.redhat.com/~rjones/

COPYRIGHT
Copyright (C) 2009-2025 Red Hat Inc.

LICENSE

BUGS
To get a list of bugs against libguestfs, use this link: https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools

To report a new bug against libguestfs, use this link: https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools

When reporting a bug, please supply:

•   The version of libguestfs.

•   Where you got libguestfs (eg. which Linux distro, compiled from source, etc)

•   Describe the bug accurately and give a way to reproduce it.

•   Run libguestfs-test-tool(1) and paste the complete, unedited output into the bug report.