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