Provided by: dracut-core_105-2ubuntu3_amd64 
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, the default location will be determined by the local configuration or
Linux distribution policy.
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
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
contains the kernel modules of the currently active kernel with version <kernel-version>.
The default location of the image is determined by the local configuration or Linux
distribution policy.
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. It is recommended to keep a copy of a general purpose image (and
corresponding kernel) as a fallback to rescue your system.
Inspecting the Contents
To see the contents of the image created by dracut, you can use the lsinitrd tool.
# lsinitrd | less
To display the contents of a file in the initramfs also use the lsinitrd tool:
# lsinitrd -f /etc/ld.so.conf
include ld.so.conf.d/*.conf
Adding dracut Modules
Some dracut modules are turned off by default and have to be activated manually. You can
do this by adding the dracut modules to the configuration file /etc/dracut.conf or
/etc/dracut.conf.d/myconf.conf. See dracut.conf(5). You can also add dracut modules on the
command line by using the -a or --add option:
# dracut --add module initramfs-module.img
To see a list of available dracut modules, use the --list-modules option:
# dracut --list-modules
Omitting dracut Modules
Sometimes you don’t want a dracut module to be included for reasons of speed, size or
functionality. To do this, either specify the omit_dracutmodules variable in the
dracut.conf or /etc/dracut.conf.d/myconf.conf configuration file (see dracut.conf(5)), or
use the -o or --omit option on the command line:
# dracut -o "multipath lvm" no-multipath-lvm.img
Adding Kernel Modules
If you need a special kernel module in the initramfs, which is not automatically picked up
by dracut, you have the use the --add-drivers option on the command line or the drivers
variable in the /etc/dracut.conf or /etc/dracut.conf.d/myconf.conf configuration file (see
dracut.conf(5)):
# dracut --add-drivers mymod initramfs-with-mymod.img
Boot parameters
An initramfs generated without the "hostonly" mode, does not contain any system
configuration files (except for some special exceptions), so the configuration has to be
done on the kernel command line. With this flexibility, you can easily boot from a changed
root partition, without the need to recompile the initramfs image. So, you could
completely change your root partition (move it inside a md raid with encryption and LVM on
top), as long as you specify the correct filesystem LABEL or UUID on the kernel command
line for your root device, dracut will find it and boot from it.
Generic initrd’s are larger, but should be able to automatically boot any bootable
configuration with appropriate boot flags (root device, network configuration information,
etc.)
The kernel command line can also be provided by the dhcp server with the root-path option.
See the section called “Network Boot”.
For a full reference of all kernel command line parameters, see dracut.cmdline(7).
To get a quick start for the suitable kernel command line on your system, use the
--print-cmdline option:
# dracut --print-cmdline
root=UUID=8b8b6f91-95c7-4da2-831b-171e12179081 rootflags=rw,relatime,discard,data=ordered rootfstype=ext4
Specifying the root Device
This is the only option dracut really needs to boot from your root partition. Because
your root partition can live in various environments, there are a lot of formats for
the root= option. The most basic one is root=<path to device node>:
root=/dev/sda2
Because device node names can change, dependent on the drive ordering, you are
encouraged to use the filesystem identifier (UUID) or filesystem label (LABEL) to
specify your root partition:
root=UUID=19e9dda3-5a38-484d-a9b0-fa6b067d0331
or
root=LABEL=myrootpartitionlabel
To see all UUIDs or LABELs on your system, do:
# ls -l /dev/disk/by-uuid
or
# ls -l /dev/disk/by-label
If your root partition is on the network see the section called “Network Boot”.
Keyboard Settings
If you have to input passwords for encrypted disk volumes, you might want to set the
keyboard layout and specify a display font.
A typical german kernel command line would contain:
rd.vconsole.font=eurlatgr rd.vconsole.keymap=de-latin1-nodeadkeys rd.locale.LANG=de_DE.UTF-8
Setting these options can override the setting stored on your system, if you use a
modern init system, like systemd.
Blacklisting Kernel Modules
Sometimes it is required to prevent the automatic kernel module loading of a specific
kernel module. To do this, just add rd.driver.blacklist=<kernel module name>, with
<kernel module name> not containing the .ko suffix, to the kernel command line. For
example:
rd.driver.blacklist=mptsas rd.driver.blacklist=nouveau
The option can be specified multiple times on the kernel command line.
Speeding up the Boot Process
If you want to speed up the boot process, you can specify as much information for
dracut on the kernel command as possible. For example, you can tell dracut, that you
root partition is not on a LVM volume or not on a raid partition, or that it lives
inside a specific crypto LUKS encrypted volume. By default, dracut searches
everywhere. A typical dracut kernel command line for a plain primary or logical
partition would contain:
rd.luks=0 rd.lvm=0 rd.md=0 rd.dm=0
This turns off every automatic assembly of LVM, MD raids, DM raids and crypto LUKS.
Of course, you could also omit the dracut modules in the initramfs creation process,
but then you would lose the possibility to turn it on on demand.
Injecting custom Files
To add your own files to the initramfs image, you have several possibilities.
The --include option let you specify a source path and a target path. For example
# dracut --include cmdline-preset /etc/cmdline.d/mycmdline.conf initramfs-cmdline-pre.img
will create an initramfs image, where the file cmdline-preset will be copied inside the
initramfs to /etc/cmdline.d/mycmdline.conf. --include can only be specified once.
# mkdir -p rd.live.overlay/etc/cmdline.d
# mkdir -p rd.live.overlay/etc/conf.d
# echo "ip=dhcp" >> rd.live.overlay/etc/cmdline.d/mycmdline.conf
# echo export FOO=testtest >> rd.live.overlay/etc/conf.d/testvar.conf
# echo export BAR=testtest >> rd.live.overlay/etc/conf.d/testvar.conf
# tree rd.live.overlay/
rd.live.overlay/
`-- etc
|-- cmdline.d
| `-- mycmdline.conf
`-- conf.d
`-- testvar.conf
# dracut --include rd.live.overlay / initramfs-rd.live.overlay.img
This will put the contents of the rd.live.overlay directory into the root of the initramfs
image.
The --install option let you specify several files, which will get installed in the
initramfs image at the same location, as they are present on initramfs creation time.
# dracut --install 'strace fsck.ext4 ssh' initramfs-dbg.img
This will create an initramfs with the strace, fsck.ext4 and ssh executables, together
with the libraries needed to start those. The --install option can be specified multiple
times.
Network Boot
If your root partition is on a network drive, you have to have the network dracut modules
installed to create a network aware initramfs image.
If you specify ip=dhcp on the kernel command line, then dracut asks a dhcp server about
the ip address for the machine. The dhcp server can also serve an additional root-path,
which will set the root device for dracut. With this mechanism, you have static
configuration on your client machine and a centralized boot configuration on your
TFTP/DHCP server. If you can’t pass a kernel command line, then you can inject
/etc/cmdline.d/mycmdline.conf, with a method described in the section called “Injecting
custom Files”.
Reducing the Image Size
To reduce the size of the initramfs, you should create it with by omitting all dracut
modules, which you know, you don’t need to boot the machine.
You can also specify the exact dracut and kernel modules to produce a very tiny
initramfs image.
For example for a NFS image, you would do:
# dracut -m "nfs network base" initramfs-nfs-only.img
Then you would boot from this image with your target machine and reduce the size once
more by creating it on the target machine with the --host-only option:
# dracut -m "nfs network base" --host-only initramfs-nfs-host-only.img
This will reduce the size of the initramfs image significantly.
TROUBLESHOOTING
If the boot process does not succeed, you have several options to debug the situation.
Identifying your problem area
1. Remove 'rhgb' and 'quiet' from the kernel command line
2. Add 'rd.shell' to the kernel command line. This will present a shell should dracut be
unable to locate your root device
3. Add 'rd.shell rd.debug log_buf_len=1M' to the kernel command line so that dracut shell
commands are printed as they are executed
4. The file /run/initramfs/rdsosreport.txt is generated, which contains all the logs and
the output of all significant tools, which are mentioned later.
If you want to save that output, simply mount /boot by hand or insert an USB stick and
mount that. Then you can store the output for later inspection.
Information to include in your report
All bug reports
In all cases, the following should be mentioned and attached to your bug report:
• The exact kernel command-line used. Typically from the bootloader configuration
file (e.g. /boot/grub2/grub.cfg) or from /proc/cmdline.
• A copy of your disk partition information from /etc/fstab, which might be obtained
booting an old working initramfs or a rescue medium.
• Turn on dracut debugging (see the debugging dracut section), and attach the file
/run/initramfs/rdsosreport.txt.
• If you use a dracut configuration file, please include /etc/dracut.conf and all
files in /etc/dracut.conf.d/*.conf
Network root device related problems
This section details information to include when experiencing problems on a system
whose root device is located on a network attached volume (e.g. iSCSI, NFS or NBD). As
well as the information from the section called “All bug reports”, include the
following information:
• Please include the output of
# /sbin/ifup <interfacename>
# ip addr show
Debugging dracut
Configure a serial console
Successfully debugging dracut will require some form of console logging during the
system boot. This section documents configuring a serial console connection to record
boot messages.
1. First, enable serial console output for both the kernel and the bootloader.
2. Open the file /boot/grub2/grub.cfg for editing. Below the line 'timeout=5', add
the following:
serial --unit=0 --speed=9600
terminal --timeout=5 serial console
3. Also in /boot/grub2/grub.cfg, add the following boot arguments to the 'kernel'
line:
console=tty0 console=ttyS0,9600
4. When finished, the /boot/grub2/grub.cfg file should look similar to the example
below.
default=0
timeout=5
serial --unit=0 --speed=9600
terminal --timeout=5 serial console
title Fedora (2.6.29.5-191.fc11.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.29.5-191.fc11.x86_64 ro root=/dev/mapper/vg_uc1-lv_root console=tty0 console=ttyS0,9600
initrd /dracut-2.6.29.5-191.fc11.x86_64.img
5. More detailed information on how to configure the kernel for console output can be
found at
http://www.faqs.org/docs/Linux-HOWTO/Remote-Serial-Console-HOWTO.html#CONFIGURE-KERNEL.
6. Redirecting non-interactive output
Note
You can redirect all non-interactive output to /dev/kmsg and the kernel will
put it out on the console when it reaches the kernel buffer by doing
# exec >/dev/kmsg 2>&1 </dev/console
Using the dracut shell
dracut offers a shell for interactive debugging in the event dracut fails to locate
your root filesystem. To enable the shell:
1. Add the boot parameter 'rd.shell' to your bootloader configuration file (e.g.
/boot/grub2/grub.cfg)
2. Remove the boot arguments 'rhgb' and 'quiet'
A sample /boot/grub2/grub.cfg bootloader configuration file is listed below.
default=0
timeout=5
serial --unit=0 --speed=9600
terminal --timeout=5 serial console
title Fedora (2.6.29.5-191.fc11.x86_64)
root (hd0,0)
kernel /vmlinuz-2.6.29.5-191.fc11.x86_64 ro root=/dev/mapper/vg_uc1-lv_root console=tty0 rd.shell
initrd /dracut-2.6.29.5-191.fc11.x86_64.img
3. If system boot fails, you will be dropped into a shell as seen in the example
below.
No root device found
Dropping to debug shell.
#
4. Use this shell prompt to gather the information requested above (see the section
called “All bug reports”).
Accessing the root volume from the dracut shell
From the dracut debug shell, you can manually perform the task of locating and
preparing your root volume for boot. The required steps will depend on how your root
volume is configured. Common scenarios include:
• A block device (e.g. /dev/sda7)
• A LVM logical volume (e.g. /dev/VolGroup00/LogVol00)
• An encrypted device (e.g. /dev/mapper/luks-4d5972ea-901c-4584-bd75-1da802417d83)
• A network attached device (e.g.
netroot=iscsi:@192.168.0.4::3260::iqn.2009-02.org.example:for.all)
The exact method for locating and preparing will vary. However, to continue with a
successful boot, the objective is to locate your root volume and create a symlink
/dev/root which points to the file system. For example, the following example
demonstrates accessing and booting a root volume that is an encrypted LVM Logical
volume.
1. Inspect your partitions using parted
# parted /dev/sda -s p
Model: ATA HTS541060G9AT00 (scsi)
Disk /dev/sda: 60.0GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Number Start End Size Type File system Flags
1 32.3kB 10.8GB 107MB primary ext4 boot
2 10.8GB 55.6GB 44.7GB logical lvm
2. You recall that your root volume was a LVM logical volume. Scan and activate any
logical volumes.
# lvm vgscan
# lvm vgchange -ay
3. You should see any logical volumes now using the command blkid:
# blkid
/dev/sda1: UUID="3de247f3-5de4-4a44-afc5-1fe179750cf7" TYPE="ext4"
/dev/sda2: UUID="Ek4dQw-cOtq-5MJu-OGRF-xz5k-O2l8-wdDj0I" TYPE="LVM2_member"
/dev/mapper/linux-root: UUID="def0269e-424b-4752-acf3-1077bf96ad2c" TYPE="crypto_LUKS"
/dev/mapper/linux-home: UUID="c69127c1-f153-4ea2-b58e-4cbfa9257c5e" TYPE="ext4"
/dev/mapper/linux-swap: UUID="47b4d329-975c-4c08-b218-f9c9bf3635f1" TYPE="swap"
4. From the output above, you recall that your root volume exists on an encrypted
block device. Following the guidance disk encryption guidance from the
Installation Guide, you unlock your encrypted root volume.
# UUID=$(cryptsetup luksUUID /dev/mapper/linux-root)
# cryptsetup luksOpen /dev/mapper/linux-root luks-$UUID
Enter passphrase for /dev/mapper/linux-root:
Key slot 0 unlocked.
5. Next, make a symbolic link to the unlocked root volume
# ln -s /dev/mapper/luks-$UUID /dev/root
6. With the root volume available, you may continue booting the system by exiting the
dracut shell
# exit
Additional dracut boot parameters
For more debugging options, see dracut.cmdline(7).
Debugging dracut on shutdown
To debug the shutdown sequence on systemd systems, you can rd.break on pre-shutdown or
shutdown.
To do this from an already booted system:
# mkdir -p /run/initramfs/etc/cmdline.d
# echo "rd.debug rd.break=pre-shutdown rd.break=shutdown" > /run/initramfs/etc/cmdline.d/debug.conf
# touch /run/initramfs/.need_shutdown
This will give you a dracut shell after the system pivot’ed back in the initramfs.
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. Despite its name, this command only
sets initrd 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 part of the kernel command line required to boot for the current disk layout.
This option does not return all kernel command line options that dracut might add to
the initrd.
--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
--add-confdir <configuration directory>
Add an extra configuration directory to use *.conf files from. If the directory is not
existed, will look for subdirectory under confdir.
Default: empty
--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.
Warning
Make sure your kernel has gzip decompression support compiled in, otherwise you
will not be able to boot. 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
https://github.com/dracut-ng/dracut-ng
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)