DRACUT(8)dracutDRACUT(8)NAMEdracut - low-level tool for generating an initramfs image
SYNOPSISdracut [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/initrd-<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/rdsosreport.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/rdsosreport.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/initrd-<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 --hostonly 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 --hostonly 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
--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
--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
--prelink
prelink binaries in the initramfs (default)
--noprelink
do not prelink 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
--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"
--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 "lzma
--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 "lzma
--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.
--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.
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 ALSOdracut.cmdline(7)dracut.conf(5)dracut 12/28/2013 DRACUT(8)
