1DRACUT(8) dracut DRACUT(8)
2
6 dracut - low-level tool for generating an initramfs/initrd image
7
9 dracut [OPTION...] [<image> [<kernel version>]]
10
12 Create an initramfs <image> for the kernel with the version <kernel
13 version>. If <kernel version> is omitted, then the version of the
14 actual running kernel is used. If <image> is omitted or empty,
15 depending on bootloader specification, the default location can be
16 /efi/<machine-id>/<kernel-version>/initrd,
17 /boot/<machine-id>/<kernel-version>/initrd,
18 /boot/efi/<machine-id>/<kernel-version>/initrd,
19 /lib/modules/<kernel-version>/initrd or
20 /boot/initramfs-<kernel-version>.img.
21 dracut creates an initial image used by the kernel for preloading the
23 block device modules (such as IDE, SCSI or RAID) which are needed to
24 access the root filesystem, mounting the root filesystem and booting
25 into the real system.
26 At boot time, the kernel unpacks that archive into RAM disk, mounts and
28 uses it as initial root file system. All finding of the root device
29 happens in this early userspace.
30 Initramfs images are also called "initrd".
32 For a complete list of kernel command line options see
34 dracut.cmdline(7).
35 If you are dropped to an emergency shell, while booting your initramfs,
37 the file /run/initramfs/rdsosreport.txt is created, which can be saved
38 to a (to be mounted by hand) partition (usually /boot) or a USB stick.
39 Additional debugging info can be produced by adding rd.debug to the
40 kernel command line. /run/initramfs/rdsosreport.txt contains all logs
41 and the output of some tools. It should be attached to any report about
42 dracut problems.
43
45 To create a initramfs image, the most simple command is:
46 # dracut
48 This will generate a general purpose initramfs image, with all possible
50 functionality resulting of the combination of the installed dracut
51 modules and system tools. The image, depending on bootloader
52 specification, can be /efi/<machine-id>/<kernel-version>/initrd,
53 /boot/<machine-id>/<kernel-version>/initrd,
54 /boot/efi/<machine-id>/<kernel-version>/initrd,
55 /lib/modules/<kernel-version>/initrd or
56 /boot/initramfs-<kernel-version>.img and contains the kernel modules of
57 the currently active kernel with version <kernel-version>.
58 If the initramfs image already exists, dracut will display an error
60 message, and to overwrite the existing image, you have to use the
61 --force option.
62 # dracut --force
64 If you want to specify another filename for the resulting image you
66 would issue a command like:
67 # dracut foobar.img
69 To generate an image for a specific kernel version, the command would
71 be:
72 # dracut foobar.img 2.6.40-1.rc5.f20
74 A shortcut to generate the image at the default location for a specific
76 kernel version is:
77 # dracut --kver 2.6.40-1.rc5.f20
79 If you want to create lighter, smaller initramfs images, you may want
81 to specify the --hostonly or -H option. Using this option, the
82 resulting image will contain only those dracut modules, kernel modules
83 and filesystems, which are needed to boot this specific machine. This
84 has the drawback, that you can’t put the disk on another controller or
85 machine, and that you can’t switch to another root filesystem, without
86 recreating the initramfs image. The usage of the --hostonly option is
87 only for experts and you will have to keep the broken pieces. At least
88 keep a copy of a general purpose image (and corresponding kernel) as a
89 fallback to rescue your system.
90 Inspecting the Contents
92 To see the contents of the image created by dracut, you can use the
93 lsinitrd tool.
94 # lsinitrd | less
96 To display the contents of a file in the initramfs also use the
98 lsinitrd tool:
99 # lsinitrd -f /etc/ld.so.conf
101 include ld.so.conf.d/*.conf
102 Adding dracut Modules
104 Some dracut modules are turned off by default and have to be activated
105 manually. You can do this by adding the dracut modules to the
106 configuration file /etc/dracut.conf or /etc/dracut.conf.d/myconf.conf.
107 See dracut.conf(5). You can also add dracut modules on the command line
108 by using the -a or --add option:
109 # dracut --add module initramfs-module.img
111 To see a list of available dracut modules, use the --list-modules
113 option:
114 # dracut --list-modules
116 Omitting dracut Modules
118 Sometimes you don’t want a dracut module to be included for reasons of
119 speed, size or functionality. To do this, either specify the
120 omit_dracutmodules variable in the dracut.conf or
121 /etc/dracut.conf.d/myconf.conf configuration file (see dracut.conf(5)),
122 or use the -o or --omit option on the command line:
123 # dracut -o "multipath lvm" no-multipath-lvm.img
125 Adding Kernel Modules
127 If you need a special kernel module in the initramfs, which is not
128 automatically picked up by dracut, you have the use the --add-drivers
129 option on the command line or the drivers variable in the
130 /etc/dracut.conf or /etc/dracut.conf.d/myconf.conf configuration file
131 (see dracut.conf(5)):
132 # dracut --add-drivers mymod initramfs-with-mymod.img
134 Boot parameters
136 An initramfs generated without the "hostonly" mode, does not contain
137 any system configuration files (except for some special exceptions), so
138 the configuration has to be done on the kernel command line. With this
139 flexibility, you can easily boot from a changed root partition, without
140 the need to recompile the initramfs image. So, you could completely
141 change your root partition (move it inside a md raid with encryption
142 and LVM on top), as long as you specify the correct filesystem LABEL or
143 UUID on the kernel command line for your root device, dracut will find
144 it and boot from it.
145 The kernel command line can also be provided by the dhcp server with
147 the root-path option. See the section called “Network Boot”.
148 For a full reference of all kernel command line parameters, see
150 dracut.cmdline(7).
151 To get a quick start for the suitable kernel command line on your
153 system, use the --print-cmdline option:
154 # dracut --print-cmdline
156 root=UUID=8b8b6f91-95c7-4da2-831b-171e12179081 rootflags=rw,relatime,discard,data=ordered rootfstype=ext4
157 Specifying the root Device
159 This is the only option dracut really needs to boot from your root
160 partition. Because your root partition can live in various
161 environments, there are a lot of formats for the root= option. The
162 most basic one is root=<path to device node>:
163 root=/dev/sda2
165 Because device node names can change, dependent on the drive
167 ordering, you are encouraged to use the filesystem identifier
168 (UUID) or filesystem label (LABEL) to specify your root partition:
169 root=UUID=19e9dda3-5a38-484d-a9b0-fa6b067d0331
171 or
173 root=LABEL=myrootpartitionlabel
175 To see all UUIDs or LABELs on your system, do:
177 # ls -l /dev/disk/by-uuid
179 or
181 # ls -l /dev/disk/by-label
183 If your root partition is on the network see the section called
185 “Network Boot”.
186 Keyboard Settings
188 If you have to input passwords for encrypted disk volumes, you
189 might want to set the keyboard layout and specify a display font.
190 A typical german kernel command line would contain:
192 rd.vconsole.font=eurlatgr rd.vconsole.keymap=de-latin1-nodeadkeys rd.locale.LANG=de_DE.UTF-8
194 Setting these options can override the setting stored on your
196 system, if you use a modern init system, like systemd.
197 Blacklisting Kernel Modules
199 Sometimes it is required to prevent the automatic kernel module
200 loading of a specific kernel module. To do this, just add
201 rd.blacklist=<kernel module name>, with <kernel module name> not
202 containing the .ko suffix, to the kernel command line. For example:
203 rd.driver.blacklist=mptsas rd.driver.blacklist=nouveau
205 The option can be specified multiple times on the kernel command
207 line.
208 Speeding up the Boot Process
210 If you want to speed up the boot process, you can specify as much
211 information for dracut on the kernel command as possible. For
212 example, you can tell dracut, that you root partition is not on a
213 LVM volume or not on a raid partition, or that it lives inside a
214 specific crypto LUKS encrypted volume. By default, dracut searches
215 everywhere. A typical dracut kernel command line for a plain
216 primary or logical partition would contain:
217 rd.luks=0 rd.lvm=0 rd.md=0 rd.dm=0
219 This turns off every automatic assembly of LVM, MD raids, DM raids
221 and crypto LUKS.
222 Of course, you could also omit the dracut modules in the initramfs
224 creation process, but then you would lose the possibility to turn
225 it on on demand.
226 Injecting custom Files
228 To add your own files to the initramfs image, you have several
229 possibilities.
230 The --include option let you specify a source path and a target path.
232 For example
233 # dracut --include cmdline-preset /etc/cmdline.d/mycmdline.conf initramfs-cmdline-pre.img
235 will create an initramfs image, where the file cmdline-preset will be
237 copied inside the initramfs to /etc/cmdline.d/mycmdline.conf. --include
238 can only be specified once.
239 # mkdir -p rd.live.overlay/etc/cmdline.d
241 # mkdir -p rd.live.overlay/etc/conf.d
242 # echo "ip=dhcp" >> rd.live.overlay/etc/cmdline.d/mycmdline.conf
243 # echo export FOO=testtest >> rd.live.overlay/etc/conf.d/testvar.conf
244 # echo export BAR=testtest >> rd.live.overlay/etc/conf.d/testvar.conf
245 # tree rd.live.overlay/
246 rd.live.overlay/
247 `-- etc
248 |-- cmdline.d
249 | `-- mycmdline.conf
250 `-- conf.d
251 `-- testvar.conf
252 # dracut --include rd.live.overlay / initramfs-rd.live.overlay.img
254 This will put the contents of the rd.live.overlay directory into the
256 root of the initramfs image.
257 The --install option let you specify several files, which will get
259 installed in the initramfs image at the same location, as they are
260 present on initramfs creation time.
261 # dracut --install 'strace fsck.ext3 ssh' initramfs-dbg.img
263 This will create an initramfs with the strace, fsck.ext3 and ssh
265 executables, together with the libraries needed to start those. The
266 --install option can be specified multiple times.
267 Network Boot
269 If your root partition is on a network drive, you have to have the
270 network dracut modules installed to create a network aware initramfs
271 image.
272 If you specify ip=dhcp on the kernel command line, then dracut asks a
274 dhcp server about the ip address for the machine. The dhcp server can
275 also serve an additional root-path, which will set the root device for
276 dracut. With this mechanism, you have static configuration on your
277 client machine and a centralized boot configuration on your TFTP/DHCP
278 server. If you can’t pass a kernel command line, then you can inject
279 /etc/cmdline.d/mycmdline.conf, with a method described in the section
280 called “Injecting custom Files”.
281 Reducing the Image Size
283 To reduce the size of the initramfs, you should create it with by
284 omitting all dracut modules, which you know, you don’t need to boot
285 the machine.
286 You can also specify the exact dracut and kernel modules to produce
288 a very tiny initramfs image.
289 For example for a NFS image, you would do:
291 # dracut -m "nfs network base" initramfs-nfs-only.img
293 Then you would boot from this image with your target machine and
295 reduce the size once more by creating it on the target machine with
296 the --host-only option:
297 # dracut -m "nfs network base" --host-only initramfs-nfs-host-only.img
299 This will reduce the size of the initramfs image significantly.
301
303 If the boot process does not succeed, you have several options to debug
304 the situation. Some of the basic operations are covered here. For more
305 information you should also visit:
306 https://www.kernel.org/pub/linux/utils/boot/dracut/dracut.html
307 Identifying your problem area
309 1. Remove 'rhgb' and 'quiet' from the kernel command line
310 2. Add 'rd.shell' to the kernel command line. This will present a
312 shell should dracut be unable to locate your root device
313 3. Add 'rd.shell rd.debug log_buf_len=1M' to the kernel command line
315 so that dracut shell commands are printed as they are executed
316 4. The file /run/initramfs/rdsosreport.txt is generated, which
318 contains all the logs and the output of all significant tools,
319 which are mentioned later.
320 If you want to save that output, simply mount /boot by hand or insert
322 an USB stick and mount that. Then you can store the output for later
323 inspection.
324 Information to include in your report
326 All bug reports
327 In all cases, the following should be mentioned and attached to
328 your bug report:
329 • The exact kernel command-line used. Typically from the
331 bootloader configuration file (e.g. /boot/grub2/grub.cfg) or
332 from /proc/cmdline.
333 • A copy of your disk partition information from /etc/fstab,
335 which might be obtained booting an old working initramfs or a
336 rescue medium.
337 • Turn on dracut debugging (see the debugging dracut section),
339 and attach the file /run/initramfs/rdsosreport.txt.
340 • If you use a dracut configuration file, please include
342 /etc/dracut.conf and all files in /etc/dracut.conf.d/*.conf
343 Network root device related problems
345 This section details information to include when experiencing
346 problems on a system whose root device is located on a network
347 attached volume (e.g. iSCSI, NFS or NBD). As well as the
348 information from the section called “All bug reports”, include the
349 following information:
350 • Please include the output of
352 # /sbin/ifup <interfacename>
354 # ip addr show
355 Debugging dracut
357 Configure a serial console
358 Successfully debugging dracut will require some form of console
359 logging during the system boot. This section documents configuring
360 a serial console connection to record boot messages.
361 1. First, enable serial console output for both the kernel and the
363 bootloader.
364 2. Open the file /boot/grub2/grub.cfg for editing. Below the line
366 'timeout=5', add the following:
367 serial --unit=0 --speed=9600
369 terminal --timeout=5 serial console
370 3. Also in /boot/grub2/grub.cfg, add the following boot arguments
372 to the 'kernel' line:
373 console=tty0 console=ttyS0,9600
375 4. When finished, the /boot/grub2/grub.cfg file should look
377 similar to the example below.
378 default=0
380 timeout=5
381 serial --unit=0 --speed=9600
382 terminal --timeout=5 serial console
383 title Fedora (2.6.29.5-191.fc11.x86_64)
384 root (hd0,0)
385 kernel /vmlinuz-2.6.29.5-191.fc11.x86_64 ro root=/dev/mapper/vg_uc1-lv_root console=tty0 console=ttyS0,9600
386 initrd /dracut-2.6.29.5-191.fc11.x86_64.img
387 5. More detailed information on how to configure the kernel for
389 console output can be found at
390 http://www.faqs.org/docs/Linux-HOWTO/Remote-Serial-Console-HOWTO.html#CONFIGURE-KERNEL.
391 6. Redirecting non-interactive output
393 Note
395 You can redirect all non-interactive output to /dev/kmsg
396 and the kernel will put it out on the console when it
397 reaches the kernel buffer by doing
398 # exec >/dev/kmsg 2>&1 </dev/console
400 Using the dracut shell
402 dracut offers a shell for interactive debugging in the event dracut
403 fails to locate your root filesystem. To enable the shell:
404 1. Add the boot parameter 'rd.shell' to your bootloader
406 configuration file (e.g. /boot/grub2/grub.cfg)
407 2. Remove the boot arguments 'rhgb' and 'quiet'
409 A sample /boot/grub2/grub.cfg bootloader configuration file is
411 listed below.
412 default=0
414 timeout=5
415 serial --unit=0 --speed=9600
416 terminal --timeout=5 serial console
417 title Fedora (2.6.29.5-191.fc11.x86_64)
418 root (hd0,0)
419 kernel /vmlinuz-2.6.29.5-191.fc11.x86_64 ro root=/dev/mapper/vg_uc1-lv_root console=tty0 rd.shell
420 initrd /dracut-2.6.29.5-191.fc11.x86_64.img
421 3. If system boot fails, you will be dropped into a shell as seen
423 in the example below.
424 No root device found
426 Dropping to debug shell.
427 #
429 4. Use this shell prompt to gather the information requested above
431 (see the section called “All bug reports”).
432 Accessing the root volume from the dracut shell
434 From the dracut debug shell, you can manually perform the task of
435 locating and preparing your root volume for boot. The required
436 steps will depend on how your root volume is configured. Common
437 scenarios include:
438 • A block device (e.g. /dev/sda7)
440 • A LVM logical volume (e.g. /dev/VolGroup00/LogVol00)
442 • An encrypted device (e.g.
444 /dev/mapper/luks-4d5972ea-901c-4584-bd75-1da802417d83)
445 • A network attached device (e.g.
447 netroot=iscsi:@192.168.0.4::3260::iqn.2009-02.org.example:for.all)
448 The exact method for locating and preparing will vary. However, to
450 continue with a successful boot, the objective is to locate your
451 root volume and create a symlink /dev/root which points to the file
452 system. For example, the following example demonstrates accessing
453 and booting a root volume that is an encrypted LVM Logical volume.
454 1. Inspect your partitions using parted
456 # parted /dev/sda -s p
458 Model: ATA HTS541060G9AT00 (scsi)
459 Disk /dev/sda: 60.0GB
460 Sector size (logical/physical): 512B/512B
461 Partition Table: msdos
462 Number Start End Size Type File system Flags
463 1 32.3kB 10.8GB 107MB primary ext4 boot
464 2 10.8GB 55.6GB 44.7GB logical lvm
465 2. You recall that your root volume was a LVM logical volume. Scan
467 and activate any logical volumes.
468 # lvm vgscan
470 # lvm vgchange -ay
471 3. You should see any logical volumes now using the command blkid:
473 # blkid
475 /dev/sda1: UUID="3de247f3-5de4-4a44-afc5-1fe179750cf7" TYPE="ext4"
476 /dev/sda2: UUID="Ek4dQw-cOtq-5MJu-OGRF-xz5k-O2l8-wdDj0I" TYPE="LVM2_member"
477 /dev/mapper/linux-root: UUID="def0269e-424b-4752-acf3-1077bf96ad2c" TYPE="crypto_LUKS"
478 /dev/mapper/linux-home: UUID="c69127c1-f153-4ea2-b58e-4cbfa9257c5e" TYPE="ext3"
479 /dev/mapper/linux-swap: UUID="47b4d329-975c-4c08-b218-f9c9bf3635f1" TYPE="swap"
480 4. From the output above, you recall that your root volume exists
482 on an encrypted block device. Following the guidance disk
483 encryption guidance from the Installation Guide, you unlock
484 your encrypted root volume.
485 # UUID=$(cryptsetup luksUUID /dev/mapper/linux-root)
487 # cryptsetup luksOpen /dev/mapper/linux-root luks-$UUID
488 Enter passphrase for /dev/mapper/linux-root:
489 Key slot 0 unlocked.
490 5. Next, make a symbolic link to the unlocked root volume
492 # ln -s /dev/mapper/luks-$UUID /dev/root
494 6. With the root volume available, you may continue booting the
496 system by exiting the dracut shell
497 # exit
499 Additional dracut boot parameters
501 For more debugging options, see dracut.cmdline(7).
502 Debugging dracut on shutdown
504 To debug the shutdown sequence on systemd systems, you can rd.break
505 on pre-shutdown or shutdown.
506 To do this from an already booted system:
508 # mkdir -p /run/initramfs/etc/cmdline.d
510 # echo "rd.debug rd.break=pre-shutdown rd.break=shutdown" > /run/initramfs/etc/cmdline.d/debug.conf
511 # touch /run/initramfs/.need_shutdown
512 This will give you a dracut shell after the system pivot’ed back in
514 the initramfs.
515
517 --kver <kernel version>
518 Set the kernel version. This enables to specify the kernel version,
519 without specifying the location of the initramfs image. For
520 example:
521 # dracut --kver 3.5.0-0.rc7.git1.2.fc18.x86_64
523 -f, --force
525 Overwrite existing initramfs file.
526 <output file> --rebuild
528 Append the current arguments to those with which the input
529 initramfs image was built. This option helps in incrementally
530 building the initramfs for testing. If optional <output file> is
531 not provided, the input initramfs provided to rebuild will be used
532 as output file.
533 -a, --add <list of dracut modules>
535 Add a space-separated list of dracut modules to the default set of
536 modules. This parameter can be specified multiple times.
537 Note
539 If the list has multiple arguments, then you have to put these
540 in quotes. For example:
541 # dracut --add "module1 module2" ...
543 --force-add <list of dracut modules>
545 Force to add a space-separated list of dracut modules to the
546 default set of modules, when -H is specified. This parameter can be
547 specified multiple times.
548 Note
550 If the list has multiple arguments, then you have to put these
551 in quotes. For example:
552 # dracut --force-add "module1 module2" ...
554 -o, --omit <list of dracut modules>
556 Omit a space-separated list of dracut modules. This parameter can
557 be specified multiple times.
558 Note
560 If the list has multiple arguments, then you have to put these
561 in quotes. For example:
562 # dracut --omit "module1 module2" ...
564 -m, --modules <list of dracut modules>
566 Specify a space-separated list of dracut modules to call when
567 building the initramfs. Modules are located in
568 /usr/lib/dracut/modules.d. This parameter can be specified multiple
569 times. This option forces dracut to only include the specified
570 dracut modules. In most cases the "--add" option is what you want
571 to use.
572 Note
574 If the list has multiple arguments, then you have to put these
575 in quotes. For example:
576 # dracut --modules "module1 module2" ...
578 -d, --drivers <list of kernel modules>
580 Specify a space-separated list of kernel modules to exclusively
581 include in the initramfs. The kernel modules have to be specified
582 without the ".ko" suffix. This parameter can be specified multiple
583 times.
584 Note
586 If the list has multiple arguments, then you have to put these
587 in quotes. For example:
588 # dracut --drivers "kmodule1 kmodule2" ...
590 --add-drivers <list of kernel modules>
592 Specify a space-separated list of kernel modules to add to the
593 initramfs. The kernel modules have to be specified without the
594 ".ko" suffix. This parameter can be specified multiple times.
595 Note
597 If the list has multiple arguments, then you have to put these
598 in quotes. For example:
599 # dracut --add-drivers "kmodule1 kmodule2" ...
601 --force-drivers <list of kernel modules>
603 See add-drivers above. But in this case it is ensured that the
604 drivers are tried to be loaded early via modprobe.
605 Note
607 If the list has multiple arguments, then you have to put these
608 in quotes. For example:
609 # dracut --force-drivers "kmodule1 kmodule2" ...
611 --omit-drivers <list of kernel modules>
613 Specify a space-separated list of kernel modules not to add to the
614 initramfs. The kernel modules have to be specified without the
615 ".ko" suffix. This parameter can be specified multiple times.
616 Note
618 If the list has multiple arguments, then you have to put these
619 in quotes. For example:
620 # dracut --omit-drivers "kmodule1 kmodule2" ...
622 --filesystems <list of filesystems>
624 Specify a space-separated list of kernel filesystem modules to
625 exclusively include in the generic initramfs. This parameter can be
626 specified multiple times.
627 Note
629 If the list has multiple arguments, then you have to put these
630 in quotes. For example:
631 # dracut --filesystems "filesystem1 filesystem2" ...
633 -k, --kmoddir <kernel directory>
635 Specify the directory, where to look for kernel modules.
636 --fwdir <dir>[:<dir>...]++
638 Specify additional directories, where to look for firmwares. This
639 parameter can be specified multiple times.
640 --libdirs <list of directories>
642 Specify a space-separated list of directories to look for libraries
643 to include in the generic initramfs. This parameter can be
644 specified multiple times.
645 Note
647 If the list has multiple arguments, then you have to put these
648 in quotes. For example:
649 # dracut --libdirs "dir1 dir2" ...
651 --kernel-cmdline <parameters>
653 Specify default kernel command line parameters.
654 --kernel-only
656 Only install kernel drivers and firmware files.
657 --no-kernel
659 Do not install kernel drivers and firmware files.
660 --early-microcode
662 Combine early microcode with ramdisk.
663 --no-early-microcode
665 Do not combine early microcode with ramdisk.
666 --print-cmdline
668 Print the kernel command line for the current disk layout.
669 --mdadmconf
671 Include local /etc/mdadm.conf file.
672 --nomdadmconf
674 Do not include local /etc/mdadm.conf file.
675 --lvmconf
677 Include local /etc/lvm/lvm.conf file.
678 --nolvmconf
680 Do not include local /etc/lvm/lvm.conf file.
681 --fscks <list of fsck tools>
683 Add a space-separated list of fsck tools, in addition to
684 dracut.conf's specification; the installation is opportunistic
685 (non-existing tools are ignored).
686 Note
688 If the list has multiple arguments, then you have to put these
689 in quotes. For example:
690 # dracut --fscks "fsck.foo barfsck" ...
692 --nofscks
694 Inhibit installation of any fsck tools.
695 --strip
697 Strip binaries in the initramfs (default).
698 --aggresive-strip
700 Strip more than just debug symbol and sections, for a smaller
701 initramfs build. The --strip option must also be specified.
702 --nostrip
704 Do not strip binaries in the initramfs.
705 --hardlink
707 Hardlink files in the initramfs (default).
708 --nohardlink
710 Do not hardlink files in the initramfs.
711 --prefix <dir>
713 Prefix initramfs files with the specified directory.
714 --noprefix
716 Do not prefix initramfs files (default).
717 -h, --help
719 Display help text and exit.
720 --debug
722 Output debug information of the build process.
723 -v, --verbose
725 Increase verbosity level (default is info(4)).
726 --version
728 Display version and exit.
729 -q, --quiet
731 Decrease verbosity level (default is info(4)).
732 -c, --conf <dracut configuration file>
734 Specify configuration file to use.
735 Default: /etc/dracut.conf
737 --confdir <configuration directory>
739 Specify configuration directory to use.
740 Default: /etc/dracut.conf.d
742 --tmpdir <temporary directory>
744 Specify temporary directory to use.
745 Default: /var/tmp
747 -r, --sysroot <sysroot directory>
749 Specify the sysroot directory to collect files from. This is useful
750 to create the initramfs image from a cross-compiled sysroot
751 directory. For the extra helper variables, see ENVIRONMENT below.
752 Default: empty
754 --sshkey <sshkey file>
756 SSH key file used with ssh-client module.
757 --logfile <logfile>
759 Logfile to use; overrides any setting from the configuration files.
760 Default: /var/log/dracut.log
762 -l, --local
764 Activates the local mode. dracut will use modules from the current
765 working directory instead of the system-wide installed modules in
766 /usr/lib/dracut/modules.d. This is useful when running dracut from
767 a git checkout.
768 -H, --hostonly
770 Host-only mode: Install only what is needed for booting the local
771 host instead of a generic host and generate host-specific
772 configuration.
773 Warning
775 If chrooted to another root other than the real root device,
776 use "--fstab" and provide a valid /etc/fstab.
777 -N, --no-hostonly
779 Disable host-only mode.
780 --hostonly-mode <mode>
782 Specify the host-only mode to use. <mode> could be one of "sloppy"
783 or "strict". In "sloppy" host-only mode, extra drivers and modules
784 will be installed, so minor hardware change won’t make the image
785 unbootable (e.g. changed keyboard), and the image is still portable
786 among similar hosts. With "strict" mode enabled, anything not
787 necessary for booting the local host in its current state will not
788 be included, and modules may do some extra job to save more space.
789 Minor change of hardware or environment could make the image
790 unbootable.
791 Default: sloppy
793 --hostonly-cmdline
795 Store kernel command line arguments needed in the initramfs.
796 --no-hostonly-cmdline
798 Do not store kernel command line arguments needed in the initramfs.
799 --no-hostonly-default-device
801 Do not generate implicit host devices like root, swap, fstab, etc.
802 Use "--mount" or "--add-device" to explicitly add devices as
803 needed.
804 --hostonly-i18n
806 Install only needed keyboard and font files according to the host
807 configuration (default).
808 --no-hostonly-i18n
810 Install all keyboard and font files available.
811 --hostonly-nics <list of nics>
813 Only enable listed NICs in the initramfs. The list can be empty, so
814 other modules can install only the necessary network drivers.
815 --persistent-policy <policy>
817 Use <policy> to address disks and partitions. <policy> can be any
818 directory name found in /dev/disk. E.g. "by-uuid", "by-label"
819 --fstab
821 Use /etc/fstab instead of /proc/self/mountinfo.
822 --add-fstab <filename>
824 Add entries of <filename> to the initramfs /etc/fstab.
825 --mount "<device> <mountpoint> <filesystem type> [<filesystem options>
827 [<dump frequency> [<fsck order>]]]"
828 Mount <device> on <mountpoint> with <filesystem type> in the
829 initramfs. <filesystem options>, <dump options> and <fsck order>
830 can be specified, see fstab manpage for the details. The default
831 <filesystem options> is "defaults". The default <dump frequency> is
832 "0". The default <fsck order> is "2".
833 --mount "<mountpoint>"
835 Like above, but <device>, <filesystem type> and <filesystem
836 options> are determined by looking at the current mounts.
837 --add-device <device>
839 Bring up <device> in initramfs, <device> should be the device name.
840 This can be useful in host-only mode for resume support when your
841 swap is on LVM or an encrypted partition. [NB --device can be used
842 for compatibility with earlier releases]
843 -i, --include <SOURCE> <TARGET>
845 Include the files in the SOURCE directory into the TARGET directory
846 in the final initramfs. If SOURCE is a file, it will be installed
847 to TARGET in the final initramfs. This parameter can be specified
848 multiple times.
849 -I, --install <file list>
851 Install the space separated list of files into the initramfs.
852 Note
854 If the list has multiple arguments, then you have to put these
855 in quotes. For example:
856 # dracut --install "/bin/foo /sbin/bar" ...
858 --install-optional <file list>
860 Install the space separated list of files into the initramfs, if
861 they exist.
862 --gzip
864 Compress the generated initramfs using gzip. This will be done by
865 default, unless another compression option or --no-compress is
866 passed. Equivalent to "--compress=gzip -9".
867 --bzip2
869 Compress the generated initramfs using bzip2.
870 Warning
872 Make sure your kernel has bzip2 decompression support compiled
873 in, otherwise you will not be able to boot. Equivalent to
874 "--compress=bzip2 -9".
875 --lzma
877 Compress the generated initramfs using lzma.
878 Warning
880 Make sure your kernel has lzma decompression support compiled
881 in, otherwise you will not be able to boot. Equivalent to
882 "--compress=lzma -9 -T0".
883 --xz
885 Compress the generated initramfs using xz.
886 Warning
888 Make sure your kernel has xz decompression support compiled in,
889 otherwise you will not be able to boot. Equivalent to
890 "--compress=xz --check=crc32 --lzma2=dict=1MiB -T0".
891 --lzo
893 Compress the generated initramfs using lzop.
894 Warning
896 Make sure your kernel has lzo decompression support compiled
897 in, otherwise you will not be able to boot. Equivalent to
898 "--compress=lzop -9".
899 --lz4
901 Compress the generated initramfs using lz4.
902 Warning
904 Make sure your kernel has lz4 decompression support compiled
905 in, otherwise you will not be able to boot. Equivalent to
906 "--compress=lz4 -l -9".
907 --zstd
909 Compress the generated initramfs using Zstandard.
910 Warning
912 Make sure your kernel has zstd decompression support compiled
913 in, otherwise you will not be able to boot. Equivalent to
914 "--compress=zstd -15 -q -T0".
915 --compress <compressor>
917 Compress the generated initramfs using the passed compression
918 program. If you pass it just the name of a compression program, it
919 will call that program with known-working arguments. If you pass a
920 quoted string with arguments, it will be called with exactly those
921 arguments. Depending on what you pass, this may result in an
922 initramfs that the kernel cannot decompress. The default value can
923 also be set via the INITRD_COMPRESS environment variable.
924 --squash-compressor <compressor>
926 Compress the squashfs image using the passed compressor and
927 compressor specific options for mksquashfs. You can refer to
928 mksquashfs manual for supported compressors and compressor specific
929 options. If squash module is not called when building the
930 initramfs, this option will not take effect.
931 --no-compress
933 Do not compress the generated initramfs. This will override any
934 other compression options.
935 --reproducible
937 Create reproducible images.
938 --no-reproducible
940 Do not create reproducible images.
941 --list-modules
943 List all available dracut modules.
944 -M, --show-modules
946 Print included module’s name to standard output during build.
947 --keep
949 Keep the initramfs temporary directory for debugging purposes.
950 --printsize
952 Print out the module install size.
953 --profile
955 Output profile information of the build process.
956 --ro-mnt
958 Mount / and /usr read-only by default.
959 -L, --stdlog <level>
961 [0-6] Specify logging level (to standard error).
962 0 - suppress any messages
964 1 - only fatal errors
965 2 - all errors
966 3 - warnings
967 4 - info
968 5 - debug info (here starts lots of output)
969 6 - trace info (and even more)
970 --regenerate-all
972 Regenerate all initramfs images at the default location with the
973 kernel versions found on the system. Additional parameters are
974 passed through.
975 -p, --parallel
977 Try to execute tasks in parallel. Currently only supported with
978 --regenerate-all (build initramfs images for all kernel versions
979 simultaneously).
980 --noimageifnotneeded
982 Do not create an image in host-only mode, if no kernel driver is
983 needed and no /etc/cmdline/*.conf will be generated into the
984 initramfs.
985 --loginstall <directory>
987 Log all files installed from the host to <directory>.
988 --uefi
990 Instead of creating an initramfs image, dracut will create an UEFI
991 executable, which can be executed by an UEFI BIOS. The default
992 output filename is
993 <EFI>/EFI/Linux/linux-$kernel$-<MACHINE_ID>-<BUILD_ID>.efi. <EFI>
994 might be /efi, /boot or /boot/efi depending on where the ESP
995 partition is mounted. The <BUILD_ID> is taken from BUILD_ID in
996 /usr/lib/os-release or if it exists /etc/os-release and is left
997 out, if BUILD_ID is non-existant or empty.
998 --no-uefi
1000 Disables UEFI mode.
1001 --no-machineid
1003 Affects the default output filename of --uefi and will discard the
1004 <MACHINE_ID> part.
1005 --uefi-stub <file>
1007 Specifies the UEFI stub loader, which will load the attached
1008 kernel, initramfs and kernel command line and boots the kernel. The
1009 default is
1010 $prefix/lib/systemd/boot/efi/linux<EFI-MACHINE-TYPE-NAME>.efi.stub.
1011 --uefi-splash-image <file>
1013 Specifies the UEFI stub loader’s splash image. Requires bitmap
1014 (.bmp) image format.
1015 --kernel-image <file>
1017 Specifies the kernel image, which to include in the UEFI
1018 executable. The default is /lib/modules/<KERNEL-VERSION>/vmlinuz or
1019 /boot/vmlinuz-<KERNEL-VERSION>.
1020 --enhanced-cpio
1022 Attempt to use the dracut-cpio binary, which optimizes archive
1023 creation for copy-on-write filesystems by using the
1024 copy_file_range(2) syscall via Rust’s io::copy(). When specified,
1025 initramfs archives are also padded to ensure optimal data alignment
1026 for extent sharing. To retain reflink data deduplication benefits,
1027 this should be used alongside the --no-compress and --no-strip
1028 parameters, with initramfs source files, --tmpdir staging area and
1029 destination all on the same copy-on-write capable filesystem.
1030
1032 INITRD_COMPRESS
1033 sets the default compression program. See --compress.
1034 DRACUT_LDCONFIG
1036 sets the ldconfig program path and options. Optional. Used for
1037 --sysroot.
1038 Default: ldconfig
1040 DRACUT_LDD
1042 sets the ldd program path and options. Optional. Used for
1043 --sysroot.
1044 Default: ldd
1046 DRACUT_TESTBIN
1048 sets the initially tested binary for detecting library paths.
1049 Optional. Used for --sysroot. In the cross-compiled sysroot, the
1050 default value (/bin/sh) is unusable, as it is an absolute symlink
1051 and points outside the sysroot directory.
1052 Default: /bin/sh
1054 DRACUT_INSTALL
1056 overrides path and options for executing dracut-install internally.
1057 Optional. Can be used to debug dracut-install while running the
1058 main dracut script.
1059 Default: dracut-install
1061 Example: DRACUT_INSTALL="valgrind dracut-install"
1063 DRACUT_COMPRESS_BZIP2, DRACUT_COMPRESS_BZIP2, DRACUT_COMPRESS_LBZIP2,
1065 DRACUT_COMPRESS_LZMA, DRACUT_COMPRESS_XZ, DRACUT_COMPRESS_GZIP,
1066 DRACUT_COMPRESS_PIGZ, DRACUT_COMPRESS_LZOP, DRACUT_COMPRESS_ZSTD,
1067 DRACUT_COMPRESS_LZ4, DRACUT_COMPRESS_CAT
1068 overrides for compression utilities to support using them from
1069 non-standard paths.
1070 Default values are the default compression utility names to be
1072 found in PATH.
1073 DRACUT_ARCH
1075 overrides the value of uname -m. Used for --sysroot.
1076 Default: empty (the value of uname -m on the host system)
1078 SYSTEMD_VERSION
1080 overrides systemd version. Used for --sysroot.
1081 SYSTEMCTL
1083 overrides the systemctl binary. Used for --sysroot.
1084 NM_VERSION
1086 overrides the NetworkManager version. Used for --sysroot.
1087 DRACUT_INSTALL_PATH
1089 overrides PATH environment for dracut-install to look for binaries
1090 relative to --sysroot. In a cross-compiled environment (e.g.
1091 Yocto), PATH points to natively built binaries that are not in the
1092 host’s /bin, /usr/bin, etc. dracut-install still needs plain /bin
1093 and /usr/bin that are relative to the cross-compiled sysroot.
1094 Default: PATH
1096 DRACUT_INSTALL_LOG_TARGET
1098 overrides DRACUT_LOG_TARGET for dracut-install. It allows running
1099 dracut-install* to run with different log target that dracut** runs
1100 with.
1101 Default: DRACUT_LOG_TARGET
1103 DRACUT_INSTALL_LOG_LEVEL
1105 overrides DRACUT_LOG_LEVEL for dracut-install. It allows running
1106 dracut-install* to run with different log level that dracut** runs
1107 with.
1108 Default: DRACUT_LOG_LEVEL
1110
1112 /var/log/dracut.log
1113 logfile of initramfs image creation
1114 /tmp/dracut.log
1116 logfile of initramfs image creation, if /var/log/dracut.log is not
1117 writable
1118 /etc/dracut.conf
1120 see dracut.conf5
1121 /etc/dracut.conf.d/*.conf
1123 see dracut.conf5
1124 /usr/lib/dracut/dracut.conf.d/*.conf
1126 see dracut.conf5
1127 Configuration in the initramfs
1129 /etc/conf.d/
1130 Any files found in /etc/conf.d/ will be sourced in the initramfs to
1131 set initial values. Command line options will override these values
1132 set in the configuration files.
1133 /etc/cmdline
1135 Can contain additional command line options. Deprecated, better use
1136 /etc/cmdline.d/*.conf.
1137 /etc/cmdline.d/*.conf
1139 Can contain additional command line options.
1140
1142 The dracut command is part of the dracut package and is available from
1143 https://dracut.wiki.kernel.org
1144
1146 Harald Hoyer
1147 Victor Lowther
1149 Amadeusz Żołnowski
1151 Hannes Reinecke
1153 Daniel Molkentin
1155 Will Woods
1157 Philippe Seewer
1159 Warren Togami
1161
1163 dracut.cmdline(7) dracut.conf(5) lsinitrd(1)
1164dracut 057-4-gb46b3749 07/01/2022 DRACUT(8)