path: root/man/dracut.8.asc

DRACUT(8)
=========
:doctype: manpage
:man source:   dracut
:man manual:   dracut
:man version:  {version}

NAME
----
dracut - low-level tool for generating an initramfs/initrd image

SYNOPSIS
--------
*dracut* [__OPTION...__] [__<image>__ [__<kernel version>__]]

DESCRIPTION
-----------

Create an initramfs <image> for the kernel with the version <kernel version>.
If <kernel version> is omitted, then the version of the actual running
kernel is used. If <image> is omitted or empty, depending on bootloader
specification, the default location can be
_/efi/<machine-id>/<kernel-version>/initrd_,
_/boot/<machine-id>/<kernel-version>/initrd_,
_/boot/efi/<machine-id>/<kernel-version>/initrd_,
_/lib/modules/<kernel-version>/initrd_ or
_/boot/initramfs-<kernel-version>.img_.

dracut creates an initial image used by the kernel for preloading the block
device modules (such as IDE, SCSI or RAID) which are needed to access the root
filesystem, mounting the root filesystem and booting into the real system.

At boot time, the kernel unpacks that archive into RAM disk, mounts and uses it
as initial root file system. All finding of the root device happens in this
early userspace.

Initramfs images are also called "initrd".

For a complete list of kernel command line options see *dracut.cmdline*(7).

If you are dropped to an emergency shell, while booting your initramfs,
the file _/run/initramfs/rdsosreport.txt_ is created, which can be saved to a
(to be mounted by hand) partition (usually /boot) or a USB stick.
Additional debugging info can be produced by adding **rd.debug** to the kernel
command line. _/run/initramfs/rdsosreport.txt_ contains all logs and the output
of some tools. It should be attached to any report about dracut problems.

USAGE
-----

include::dracut.usage.asc[]

OPTIONS
-------
**--kver** _<kernel version>_::
    Set the kernel version. This enables to specify the kernel version, without
    specifying the location of the initramfs image. For example:
----
# dracut --kver 3.5.0-0.rc7.git1.2.fc18.x86_64
----

**-f, --force**::
    Overwrite existing initramfs file.

_<output file>_ **--rebuild**::
    Append the current arguments to those with which the input initramfs image
    was built. This option helps in incrementally building the initramfs for
    testing. If optional _<output file>_ is not provided, the input initramfs
    provided to rebuild will be used as output file.

**-a, --add** _<list of dracut modules>_::
    Add a space-separated list of dracut modules to the default set of modules.
    This parameter can be specified multiple times.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --add "module1 module2"  ...
----
===============================

**--force-add** _<list of dracut modules>_::
    Force to add a space-separated list of dracut modules to the default set of
    modules, when -H is specified. This parameter can be specified multiple
    times.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --force-add "module1 module2"  ...
----
===============================

**-o, --omit** _<list of dracut modules>_::
    Omit a space-separated list of dracut modules. This parameter can be
    specified multiple times.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --omit "module1 module2"  ...
----
===============================

**-m, --modules** _<list of dracut modules>_::
    Specify a space-separated list of dracut modules to call when building the
    initramfs. Modules are located in _/usr/lib/dracut/modules.d_. This
    parameter can be specified multiple times.
    This option forces dracut to only include the specified dracut modules.
    In most cases the "--add" option is what you want to use.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --modules "module1 module2"  ...
----
===============================

**-d, --drivers** _<list of kernel modules>_::
    Specify a space-separated list of kernel modules to exclusively include
    in the initramfs. The kernel modules have to be specified without the ".ko"
    suffix. This parameter can be specified multiple times.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --drivers "kmodule1 kmodule2"  ...
----
===============================

**--add-drivers** _<list of kernel modules>_::
    Specify a space-separated list of kernel modules to add to the initramfs.
    The kernel modules have to be specified without the ".ko" suffix. This
    parameter can be specified multiple times.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --add-drivers "kmodule1 kmodule2"  ...
----
===============================

**--force-drivers** _<list of kernel modules>_::
    See add-drivers above. But in this case it is ensured that the drivers
    are tried to be loaded early via modprobe.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --force-drivers "kmodule1 kmodule2"  ...
----
===============================

**--omit-drivers** _<list of kernel modules>_::
    Specify a space-separated list of kernel modules not to add to the
    initramfs.
    The kernel modules have to be specified without the ".ko" suffix. This
    parameter can be specified multiple times.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --omit-drivers "kmodule1 kmodule2"  ...
----
===============================

**--filesystems** _<list of filesystems>_::
    Specify a space-separated list of kernel filesystem modules to exclusively
    include in the generic initramfs. This parameter can be specified multiple
    times.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --filesystems "filesystem1 filesystem2"  ...
----
===============================

**-k, --kmoddir** _<kernel directory>_::
    Specify the directory, where to look for kernel modules.

**--fwdir** _<dir>[:<dir>...]++_::
    Specify additional directories, where to look for firmwares. This parameter
    can be specified multiple times.

**--libdirs** _<list of directories>_::
    Specify a space-separated list of directories to look for libraries to
    include in the generic initramfs. This parameter can be specified multiple
    times.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --libdirs "dir1 dir2"  ...
----
===============================

**--kernel-cmdline <parameters>**::
    Specify default kernel command line parameters.

**--kernel-only**::
    Only install kernel drivers and firmware files.

**--no-kernel**::
    Do not install kernel drivers and firmware files.

**--early-microcode**::
    Combine early microcode with ramdisk.

**--no-early-microcode**::
    Do not combine early microcode with ramdisk.

**--print-cmdline**::
    Print the kernel command line for the current disk layout.

**--mdadmconf**::
    Include local _/etc/mdadm.conf_ file.

**--nomdadmconf**::
    Do not include local _/etc/mdadm.conf_ file.

**--lvmconf**::
    Include local _/etc/lvm/lvm.conf_ file.

**--nolvmconf**::
    Do not include local _/etc/lvm/lvm.conf_ file.

**--fscks** _<list of fsck tools>_::
    Add a space-separated list of fsck tools, in addition to _dracut.conf_'s
    specification; the installation is opportunistic (non-existing tools are
    ignored).
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --fscks "fsck.foo barfsck"  ...
----
===============================

**--nofscks**::
    Inhibit installation of any fsck tools.

**--strip**::
    Strip binaries in the initramfs (default).

**--aggressive-strip**::
    Strip more than just debug symbol and sections, for a smaller initramfs
    build. The --strip option must also be specified.

**--nostrip**::
    Do not strip binaries in the initramfs.

**--hardlink**::
    Hardlink files in the initramfs (default).

**--nohardlink**::
    Do not hardlink files in the initramfs.

**--prefix** _<dir>_::
    Prefix initramfs files with the specified directory.

**--noprefix**::
    Do not prefix initramfs files (default).

**-h, --help**::
    Display help text and exit.

**--debug**::
    Output debug information of the build process.

**-v, --verbose**::
    Increase verbosity level (default is info(4)).

**--version**::
    Display version and exit.

**-q, --quiet**::
    Decrease verbosity level (default is info(4)).

**-c, --conf** _<dracut configuration file>_::
    Specify configuration file to use.
+
Default:
   _/etc/dracut.conf_

**--confdir** _<configuration directory>_::
    Specify configuration directory to use.
+
Default:
   _/etc/dracut.conf.d_

**--tmpdir** _<temporary directory>_::
    Specify temporary directory to use.
+
Default:
   _/var/tmp_

**-r, --sysroot** _<sysroot directory>_::
    Specify the sysroot directory to collect files from.
    This is useful to create the initramfs image from
    a cross-compiled sysroot directory. For the extra helper
    variables, see *ENVIRONMENT* below.
+
Default:
    _empty_

**--sshkey** _<sshkey file>_::
    SSH key file used with ssh-client module.

**--logfile** _<logfile>_::
    Logfile to use; overrides any setting from the configuration files.
+
Default:
    _/var/log/dracut.log_

**-l, --local**::
    Activates the local mode. dracut will use modules from the current working
    directory instead of the system-wide installed modules in
    _/usr/lib/dracut/modules.d_.
    This is useful when running dracut from a git checkout.

**-H, --hostonly**::
    Host-only mode: Install only what is needed for booting the local host
    instead of a generic host and generate host-specific configuration.
+
[WARNING]
====
If chrooted to another root other than the real root device, use "--fstab" and
provide a valid _/etc/fstab_.
====

**-N, --no-hostonly**::
    Disable host-only mode.

**--hostonly-mode _<mode>_**::
    Specify the host-only mode to use. _<mode>_ could be one of "sloppy" or
    "strict".
    In "sloppy" host-only mode, extra drivers and modules will be installed, so
    minor hardware change won't make the image unbootable (e.g. changed
    keyboard), and the image is still portable among similar hosts.
    With "strict" mode enabled, anything not necessary for booting the local
    host in its current state will not be included, and modules may do some
    extra job to save more space. Minor change of hardware or environment could
    make the image unbootable.
+
Default:
    _sloppy_

**--hostonly-cmdline**::
    Store kernel command line arguments needed in the initramfs.

**--no-hostonly-cmdline**::
    Do not store kernel command line arguments needed in the initramfs.

**--no-hostonly-default-device**::
    Do not generate implicit host devices like root, swap, fstab, etc.
    Use "--mount" or "--add-device" to explicitly add devices as needed.

**--hostonly-i18n**::
    Install only needed keyboard and font files according to the host
    configuration (default).

**--no-hostonly-i18n**::
    Install all keyboard and font files available.

**--hostonly-nics** _<list of nics>_::
    Only enable listed NICs in the initramfs. The list can be empty, so other
    modules can install only the necessary network drivers.

**--persistent-policy** _<policy>_::
    Use _<policy>_ to address disks and partitions.
    _<policy>_ can be any directory name found in /dev/disk (e.g. "by-uuid",
    "by-label"), or "mapper" to use /dev/mapper device names (default).

**--fstab**::
    Use _/etc/fstab_ instead of _/proc/self/mountinfo_.

**--add-fstab** _<filename>_::
    Add entries of _<filename>_ to the initramfs /etc/fstab.

**--mount** "_<device>_ _<mountpoint>_ _<filesystem type>_ [_<filesystem options>_ [_<dump frequency>_ [_<fsck order>_]]]"::
    Mount _<device>_ on _<mountpoint>_ with _<filesystem type>_ in the
    initramfs. _<filesystem options>_, _<dump options>_ and _<fsck order>_ can
    be specified, see fstab manpage for the details.
    The default _<filesystem options>_ is "defaults".
    The default _<dump frequency>_ is "0".
    The default _<fsck order>_ is "2".

**--mount** "_<mountpoint>_"::
    Like above, but _<device>_, _<filesystem type>_ and _<filesystem options>_
    are determined by looking at the current mounts.

**--add-device** _<device>_ ::
    Bring up _<device>_ in initramfs, _<device>_ should be the device name.
    This can be useful in host-only mode for resume support when your swap is on
    LVM or an encrypted partition.
    [NB --device can be used for compatibility with earlier releases]

**-i, --include** _<SOURCE>_ _<TARGET>_::
    Include the files in the SOURCE directory into the
    TARGET directory in the final initramfs. If SOURCE is a file, it will be
    installed to TARGET in the final initramfs. This parameter can be specified
    multiple times.

**-I, --install** _<file list>_::
    Install the space separated list of files into the initramfs.
+
[NOTE]
===============================
If the list has multiple arguments, then you have to put these in quotes. For
example:
----
# dracut --install "/bin/foo /sbin/bar"  ...
----
===============================

**--install-optional** _<file list>_::
    Install the space separated list of files into the initramfs, if they exist.

**--gzip**::
    Compress the generated initramfs using gzip. This will be done by default,
    unless another compression option or --no-compress is passed. Equivalent to
    "--compress=gzip -9".

**--bzip2**::
    Compress the generated initramfs using bzip2.
+
[WARNING]
====
Make sure your kernel has bzip2 decompression support compiled in, otherwise you
will not be able to boot. Equivalent to "--compress=bzip2 -9".
====

**--lzma**::
    Compress the generated initramfs using lzma.
+
[WARNING]
====
Make sure your kernel has lzma decompression support compiled in, otherwise you
will not be able to boot. Equivalent to "--compress=lzma -9 -T0".
====

**--xz**::
    Compress the generated initramfs using xz.
+
[WARNING]
====
Make sure your kernel has xz decompression support compiled in, otherwise you
will not be able to boot. Equivalent to
"--compress=xz --check=crc32 --lzma2=dict=1MiB -T0".
====

**--lzo**::
    Compress the generated initramfs using lzop.
+
[WARNING]
====
Make sure your kernel has lzo decompression support compiled in, otherwise you
will not be able to boot. Equivalent to "--compress=lzop -9".
====

**--lz4**::
    Compress the generated initramfs using lz4.
+
[WARNING]
====
Make sure your kernel has lz4 decompression support compiled in, otherwise you
will not be able to boot. Equivalent to "--compress=lz4 -l -9".
====

**--zstd**::
    Compress the generated initramfs using Zstandard.
+
[WARNING]
====
Make sure your kernel has zstd decompression support compiled in, otherwise you
will not be able to boot. Equivalent to "--compress=zstd -15 -q -T0".
====

**--compress** _<compressor>_::
    Compress the generated initramfs using the passed compression program. If
    you pass it just the name of a compression program, it will call that
    program with known-working arguments. If you pass a quoted string with
    arguments, it will be called with exactly those arguments. Depending on what
    you pass, this may result in an initramfs that the kernel cannot decompress.
    The default value can also be set via the _INITRD_COMPRESS_ environment
    variable.

**--squash-compressor** _<compressor>_::
    Compress the squashfs image using the passed compressor and compressor
    specific options for mksquashfs. You can refer to mksquashfs manual for
    supported compressors and compressor specific options. If squash module is
    not called when building the initramfs, this option will not take effect.

**--no-compress**::
    Do not compress the generated initramfs. This will override any other
    compression options.

**--reproducible**::
    Create reproducible images.

**--no-reproducible**::
    Do not create reproducible images.

**--list-modules**::
    List all available dracut modules.

**-M, --show-modules**::
    Print included module's name to standard output during build.

**--keep**::
    Keep the initramfs temporary directory for debugging purposes.

**--printsize**::
    Print out the module install size.

**--profile**::
    Output profile information of the build process.

**--ro-mnt**::
    Mount / and /usr read-only by default.

**-L, --stdlog** _<level>_::
    [0-6] Specify logging level (to standard error).
----
          0 - suppress any messages
          1 - only fatal errors
          2 - all errors
          3 - warnings
          4 - info
          5 - debug info (here starts lots of output)
          6 - trace info (and even more)
----

**--regenerate-all**::
    Regenerate all initramfs images at the default location with the kernel
    versions found on the system. Additional parameters are passed through.

**-p, --parallel**::
    Try to execute tasks in parallel. Currently only supported with
    **--regenerate-all** (build initramfs images for all kernel
    versions simultaneously).

**--noimageifnotneeded**::
    Do not create an image in host-only mode, if no kernel driver is needed
and no /etc/cmdline/*.conf will be generated into the initramfs.

**--loginstall _<directory>_**::
    Log all files installed from the host to _<directory>_.

**--uefi**::
    Instead of creating an initramfs image, dracut will create an UEFI
    executable, which can be executed by an UEFI BIOS. The default output
    filename is _<EFI>/EFI/Linux/linux-$kernel$-<MACHINE_ID>-<BUILD_ID>.efi_.
    <EFI> might be _/efi_, _/boot_ or _/boot/efi_ depending on where the ESP
    partition is mounted. The <BUILD_ID> is taken from BUILD_ID in
    _/usr/lib/os-release_ or if it exists _/etc/os-release_ and is left out,
    if BUILD_ID is non-existent or empty.

**--no-uefi**::
    Disables UEFI mode.

**--no-machineid**::
    Affects the default output filename of **--uefi** and will discard the
    <MACHINE_ID> part.

**--uefi-stub _<file>_**::
    Specifies the UEFI stub loader, which will load the attached kernel,
    initramfs and kernel command line and boots the kernel. The default is
    _$prefix/lib/systemd/boot/efi/linux<EFI-MACHINE-TYPE-NAME>.efi.stub_.

**--uefi-splash-image _<file>_**::
    Specifies the UEFI stub loader's splash image. Requires bitmap (**.bmp**)
    image format.

**--kernel-image _<file>_**::
    Specifies the kernel image, which to include in the UEFI executable. The
    default is _/lib/modules/<KERNEL-VERSION>/vmlinuz_ or
    _/boot/vmlinuz-<KERNEL-VERSION>_.

**--sbat <parameters>**::
    Specifies the SBAT parameters, which to include in the UEFI executable. By default
    the default SBAT string added is "sbat,1,SBAT Version,sbat,1,
    https://github.com/rhboot/shim/blob/main/SBAT.md".

**--enhanced-cpio**::
    Attempt to use the dracut-cpio binary, which optimizes archive creation for
    copy-on-write filesystems by using the copy_file_range(2) syscall via Rust's
    io::copy(). When specified, initramfs archives are also padded to ensure
    optimal data alignment for extent sharing. To retain reflink data
    deduplication benefits, this should be used alongside the **--no-compress**
    and **--nostrip** parameters, with initramfs source files, **--tmpdir**
    staging area and destination all on the same copy-on-write capable
    filesystem.

ENVIRONMENT
-----------

_INITRD_COMPRESS_::
    sets the default compression program. See **--compress**.

_DRACUT_LDCONFIG_::
    sets the _ldconfig_ program path and options. Optional.
    Used for **--sysroot**.
+
Default:
    _ldconfig_

_DRACUT_LDD_::
    sets the _ldd_ program path and options. Optional.
    Used for **--sysroot**.
+
Default:
    _ldd_

_DRACUT_TESTBIN_::
    sets the initially tested binary for detecting library paths.
    Optional. Used for **--sysroot**. In the cross-compiled sysroot,
    the default value (_/bin/sh_) is unusable, as it is an absolute
    symlink and points outside the sysroot directory.
+
Default:
    _/bin/sh_

_DRACUT_INSTALL_::
    overrides path and options for executing _dracut-install_ internally.
    Optional. Can be used to debug _dracut-install_ while running the
    main dracut script.
+
Default:
    _dracut-install_
+
Example:
    DRACUT_INSTALL="valgrind dracut-install"

_DRACUT_COMPRESS_BZIP2_::
_DRACUT_COMPRESS_LBZIP2_::
_DRACUT_COMPRESS_LZMA_::
_DRACUT_COMPRESS_XZ_::
_DRACUT_COMPRESS_GZIP_::
_DRACUT_COMPRESS_PIGZ_::
_DRACUT_COMPRESS_LZOP_::
_DRACUT_COMPRESS_ZSTD_::
_DRACUT_COMPRESS_LZ4_::
_DRACUT_COMPRESS_CAT_::
    overrides for compression utilities to support using them from
    non-standard paths.
+
Default values are the default compression utility names to be found in **PATH**.

_DRACUT_ARCH_::
    overrides the value of **uname -m**. Used for **--sysroot**.
+
Default:
    _empty_ (the value of **uname -m** on the host system)

_SYSTEMD_VERSION_::
    overrides systemd version. Used for **--sysroot**.

_SYSTEMCTL_::
    overrides the systemctl binary. Used for **--sysroot**.

_NM_VERSION_::
    overrides the NetworkManager version. Used for **--sysroot**.

_DRACUT_INSTALL_PATH_::
    overrides **PATH** environment for **dracut-install** to look for
    binaries relative to **--sysroot**. In a cross-compiled environment
    (e.g. Yocto), PATH points to natively built binaries that are not
    in the host's /bin, /usr/bin, etc. **dracut-install** still needs plain
    /bin and /usr/bin that are relative to the cross-compiled sysroot.
+
Default:
    _PATH_

_DRACUT_INSTALL_LOG_TARGET_::
    overrides **DRACUT_LOG_TARGET** for **dracut-install**. It allows
    running **dracut-install* to run with different log target that
    **dracut** runs with.
+
Default:
    _DRACUT_LOG_TARGET_

_DRACUT_INSTALL_LOG_LEVEL_::
    overrides **DRACUT_LOG_LEVEL** for **dracut-install**. It allows
    running **dracut-install* to run with different log level that
    **dracut** runs with.
+
Default:
    _DRACUT_LOG_LEVEL_

FILES
-----
_/var/log/dracut.log_::
    logfile of initramfs image creation

_/tmp/dracut.log_::
    logfile of initramfs image creation, if _/var/log/dracut.log_ is not
    writable

_/etc/dracut.conf_::
    see dracut.conf5

_/etc/dracut.conf.d/*.conf_::
    see dracut.conf5

_/usr/lib/dracut/dracut.conf.d/*.conf_::
    see dracut.conf5

Configuration in the initramfs
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
_/etc/conf.d/_::
    Any files found in _/etc/conf.d/_ will be sourced in the initramfs to
    set initial values. Command line options will override these values
    set in the configuration files.

_/etc/cmdline_::
    Can contain additional command line options. Deprecated, better use
    /etc/cmdline.d/*.conf.

_/etc/cmdline.d/*.conf_::
    Can contain additional command line options.

AVAILABILITY
------------
The dracut command is part of the dracut package and is available from
link:$$https://github.com/dracutdevs/dracut$$[https://github.com/dracutdevs/dracut]

AUTHORS
-------
Harald Hoyer

Victor Lowther

Amadeusz Żołnowski

Hannes Reinecke

Daniel Molkentin

Will Woods

Philippe Seewer

Warren Togami

SEE ALSO
--------
*dracut.cmdline*(7) *dracut.conf*(5) *lsinitrd*(1)