systemd-dissect(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | COMMANDS | OPTIONS | EXIT STATUS | SEE ALSO | NOTES | COLOPHON

SYSTEMD-DISSECT(1)           systemd-dissect          SYSTEMD-DISSECT(1)

NAME         top

       systemd-dissect - Dissect file system OS images

SYNOPSIS         top

       systemd-dissect [OPTIONS...] IMAGE

       systemd-dissect [OPTIONS...] --mount IMAGE PATH

       systemd-dissect [OPTIONS...] --copy-from IMAGE PATH [TARGET]

       systemd-dissect [OPTIONS...] --copy-to IMAGE [SOURCE] PATH

DESCRIPTION         top

       systemd-dissect is a tool for introspecting and interacting with
       file system OS disk images. It supports four different
       operations:

        1. Show general OS image information, including the image's
           os-release(5) data, machine ID, partition information and
           more.

        2. Mount an OS image to a local directory. In this mode it will
           dissect the OS image and mount the included partitions
           according to their designation onto a directory and possibly
           sub-directories.

        3. Copy files and directories in and out of an OS image.

       The tool may operate on three types of OS images:

        1. OS disk images containing a GPT partition table envelope,
           with partitions marked according to the Discoverable
           Partitions Specification[1].

        2. OS disk images containing just a plain file-system without an
           enveloping partition table. (This file system is assumed to
           be the root file system of the OS.)

        3. OS disk images containing a GPT or MBR partition table, with
           a single partition only. (This partition is assumed to
           contain the root file system of the OS.)

       OS images may use any kind of Linux-supported file systems. In
       addition they may make use of LUKS disk encryption, and contain
       Verity integrity information. Note that qualifying OS images may
       be booted with systemd-nspawn(1)'s --image= switch, and be used
       as root file system for system service using the RootImage= unit
       file setting, see systemd.exec(5).

       Note that the partition table shown when invoked without command
       switch (as listed below) does not necessarily show all partitions
       included in the image, but just the partitions that are
       understood and considered part of an OS disk image. Specifically,
       partitions of unknown types are ignored, as well as duplicate
       partitions (i.e. more than one per partition type), as are root
       and /usr/ partitions of architectures not compatible with the
       local system. In other words: this tool will display what it
       operates with when mounting the image. To display the complete
       list of partitions use a tool such as fdisk(8).

COMMANDS         top

       If neither of the command switches listed below are passed the
       specified disk image is opened and general information about the
       image and the contained partitions and their use is shown.

       --mount, -m
           Mount the specified OS image to the specified directory. This
           will dissect the image, determine the OS root file system —
           as well as possibly other partitions — and mount them to the
           specified directory. If the OS image contains multiple
           partitions marked with the Discoverable Partitions
           Specification[1] multiple nested mounts are established. This
           command expects two arguments: a path to an image file and a
           path to a directory where to mount the image.

           To unmount an OS image mounted like this use umount(8)'s -R
           switch (for recursive operation), so that the OS image and
           all nested partition mounts are unmounted.

           When the OS image contains LUKS encrypted or Verity integrity
           protected file systems appropriate volumes are automatically
           set up and marked for automatic disassembly when the image is
           unmounted.

           The OS image may either be specified as path to an OS image
           stored in a regular file or may refer to block device node
           (in the latter case the block device must be the "whole"
           device, i.e. not a partition device). (The other supported
           commands described here support this, too.)

           All mounted file systems are checked with the appropriate
           fsck(8) implementation in automatic fixing mode, unless
           explicitly turned off (--fsck=no) or read-only operation is
           requested (--read-only).

       -M
           This is a shortcut for --mount --mkdir.

       --copy-from, -x
           Copies a file or directory from the specified OS image into
           the specified location on the host file system. Expects three
           arguments: a path to an image file, a source path (relative
           to the image's root directory) and a destination path
           (relative to the current working directory, or an absolute
           path, both outside of the image). If the destination path is
           omitted or specified as dash ("-"), the specified file is
           written to standard output. If the source path in the image
           file system refers to a regular file it is copied to the
           destination path. In this case access mode, extended
           attributes and timestamps are copied as well, but file
           ownership is not. If the source path in the image refers to a
           directory, it is copied to the destination path, recursively
           with all containing files and directories. In this case the
           file ownership is copied too.

       --copy-to, -a
           Copies a file or directory from the specified location in the
           host file system into the specified OS image. Expects three
           arguments: a path to an image file, a source path (relative
           to the current working directory, or an absolute path, both
           outside of the image) and a destination path (relative to the
           image's root directory). If the source path is omitted or
           specified as dash ("-"), the data to write is read from
           standard input. If the source path in the host file system
           refers to a regular file, it is copied to the destination
           path. In this case access mode, extended attributes and
           timestamps are copied as well, but file ownership is not. If
           the source path in the host file system refers to a directory
           it is copied to the destination path, recursively with all
           containing files and directories. In this case the file
           ownership is copied too.

           As with --mount file system checks are implicitly run before
           the copy operation begins.

       -h, --help
           Print a short help text and exit.

       --version
           Print a short version string and exit.

OPTIONS         top

       The following options are understood:

       --read-only, -r
           Operate in read-only mode. By default --mount will establish
           writable mount points. If this option is specified they are
           established in read-only mode instead.

       --fsck=no
           Turn off automatic file system checking. By default when an
           image is accessed for writing (by --mount or --copy-to) the
           file systems contained in the OS image are automatically
           checked using the appropriate fsck(8) command, in automatic
           fixing mode. This behavior may be switched off using
           --fsck=no.

       --growfs=no
           Turn off automatic growing of accessed file systems to their
           partition size, if marked for that in the GPT partition
           table. By default when an image is accessed for writing (by
           --mount or --copy-to) the file systems contained in the OS
           image are automatically grown to their partition sizes, if
           bit 59 in the GPT partition flags is set for partition types
           that are defined by the Discoverable Partitions
           Specification[1]. This behavior may be switched off using
           --growfs=no. File systems are grown automatically on access
           if all of the following conditions are met:

            1. The file system is mounted writable

            2. The file system currently is smaller than the partition
               it is contained in (and thus can be grown)

            3. The image contains a GPT partition table

            4. The file system is stored on a partition defined by the
               Discoverable Partitions Specification

            5. Bit 59 of the GPT partition flags for this partition is
               set, as per specification

            6. The --growfs=no option is not passed.

       --mkdir
           If combined with --mount the directory to mount the OS image
           to is created if it is missing. Note that the directory is
           not automatically removed when the disk image is unmounted
           again.

       --discard=
           Takes one of "disabled", "loop", "all", "crypto". If
           "disabled" the image is accessed with empty block discarding
           turned off. If "loop" discarding is enabled if operating on a
           regular file. If "crypt" discarding is enabled even on
           encrypted file systems. If "all" discarding is
           unconditionally enabled.

       --root-hash=, --root-hash-sig=, --verity-data=
           Configure various aspects of Verity data integrity for the OS
           image. Option --root-hash= specifies a hex-encoded top-level
           Verity hash to use for setting up the Verity integrity
           protection. Option --root-hash-sig= specifies the path to a
           file containing a PKCS#7 signature for the hash. This
           signature is passed to the kernel during activation, which
           will match it against signature keys available in the kernel
           keyring. Option --verity-data= specifies a path to a file
           with the Verity data to use for the OS image, in case it is
           stored in a detached file. It is recommended to embed the
           Verity data directly in the image, using the Verity
           mechanisms in the Discoverable Partitions Specification[1].

       --no-pager
           Do not pipe output into a pager.

       --no-legend
           Do not print the legend, i.e. column headers and the footer
           with hints.

       --json=MODE
           Shows output formatted as JSON. Expects one of "short" (for
           the shortest possible output without any redundant whitespace
           or line breaks), "pretty" (for a pretty version of the same,
           with indentation and line breaks) or "off" (to turn off JSON
           output, the default).

EXIT STATUS         top

       On success, 0 is returned, a non-zero failure code otherwise.

SEE ALSO         top

       systemd(1), systemd-nspawn(1), systemd.exec(5), Discoverable
       Partitions Specification[1], umount(8), fdisk(8)

NOTES         top

        1. Discoverable Partitions Specification
           https://systemd.io/DISCOVERABLE_PARTITIONS

COLOPHON         top

       This page is part of the systemd (systemd system and service
       manager) project.  Information about the project can be found at
       ⟨http://www.freedesktop.org/wiki/Software/systemd⟩.  If you have
       a bug report for this manual page, see
       ⟨http://www.freedesktop.org/wiki/Software/systemd/#bugreports⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/systemd/systemd.git⟩ on 2021-08-27.  (At that
       time, the date of the most recent commit that was found in the
       repository was 2021-08-27.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

systemd 249                                           SYSTEMD-DISSECT(1)