Provided by: dracut_027-1_all 
NAME
dracut - low-level tool for generating an initramfs 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, then the
default location /boot/initramfs-<kernel version>.img is used.
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.
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/sosreport.txt is created, which can be safed 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/sosreport.txt contains all logs and the output of some tools. It
should be attached to any report about dracut problems.
EXAMPLE
To create a initramfs image, the most simple command is:
# dracut
This will generate a general purpose initramfs image, with all possible functionality resulting of the
combination of the installed dracut modules and system tools. The image is /boot/initramfs-<kernel
version>.img and contains the kernel modules of the currently active kernel with version <kernel
version>.
If the initramfs image already exists, dracut will display an error message, and to overwrite the
existing image, you have to use the --force option.
# dracut --force
If you want to specify another filename for the resulting image you would issue a command like:
# dracut foobar.img
To generate an image for a specific kernel version, the command would be:
# dracut foobar.img 2.6.40-1.rc5.f20
A shortcut to generate the image at the default location for a specific kernel version is:
# dracut --kver 2.6.40-1.rc5.f20
If you want to create lighter, smaller initramfs images, you may want to specify the --host-only or -H
option. Using this option, the resulting image will contain only those dracut modules, kernel modules and
filesystems, which are needed to boot this specific machine. This has the drawback, that you can’t put
the disk on another controller or machine, and that you can’t switch to another root filesystem, without
recreating the initramfs image. The usage of the --host-only option is only for experts and you will have
to keep the broken pieces. At least keep a copy of a general purpose image (and corresponding kernel) as
a fallback to rescue your system.
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.
-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.
Note
If [LIST] has multiple arguments, then you have to put these in quotes. For example:
# dracut --modules "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 [LIST] has multiple arguments, then you have to put these in quotes. For example:
# dracut --omit "module1 module2" ...
-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 [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 [LIST] has multiple arguments, then you have to put these in quotes. For example:
# dracut --force-add "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 [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 [LIST] has multiple arguments, then you have to put these in quotes. For example:
# dracut --add-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 [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 [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.
--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
--mdadmconf
include local /etc/mdadm.conf
--nomdadmconf
do not include local /etc/mdadm.conf
--lvmconf
include local /etc/lvm/lvm.conf
--nolvmconf
do not include local /etc/lvm/lvm.conf
--fscks [LIST]
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 [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)
--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))
-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
--sshkey <sshkey file>
ssh key file used with ssh-client module.
-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
--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>"
Mount <device> on <mountpoint> with <filesystem type> and <filesystem options> in the initramfs
--add-device <device>
Bring up <device> in initramfs, <device> should be the device name. This can be useful in hostonly
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 [LIST] has multiple arguments, then you have to put these in quotes. For example:
# dracut --install "/bin/foo /sbin/bar" ...
--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"
--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"
--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"
--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.
--no-compress
Do not compress the generated initramfs. This will override any other compression options.
--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.
--regenerate-all
Regenerate all initramfs images at the default location with the kernel versions found on the system.
Additional parameters are passed through.
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 https://dracut.wiki.kernel.org
AUTHORS
Harald Hoyer
Victor Lowther
Philippe Seewer
Warren Togami
Amadeusz Żołnowski
Jeremy Katz
David Dillow
Will Woods
SEE ALSO
dracut.cmdline(7) dracut.conf(5)