NAME

       systemd-dissect - Dissect file system OS images

SYNOPSIS

       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

       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

       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

       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

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

SEE ALSO

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

NOTES

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