1 <?xml version='
1.0'
?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC
"-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6 SPDX-License-Identifier: LGPL-2.1+
8 This file is part of systemd.
10 Copyright 2012 Lennart Poettering
12 systemd is free software; you can redistribute it and/or modify it
13 under the terms of the GNU Lesser General Public License as published by
14 the Free Software Foundation; either version 2.1 of the License, or
15 (at your option) any later version.
17 systemd is distributed in the hope that it will be useful, but
18 WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 Lesser General Public License for more details.
22 You should have received a copy of the GNU Lesser General Public License
23 along with systemd; If not, see <http://www.gnu.org/licenses/>.
26 <refentry id=
"kernel-command-line">
29 <title>kernel-command-line
</title>
30 <productname>systemd
</productname>
34 <contrib>Developer
</contrib>
35 <firstname>Lennart
</firstname>
36 <surname>Poettering
</surname>
37 <email>lennart@poettering.net
</email>
43 <refentrytitle>kernel-command-line
</refentrytitle>
44 <manvolnum>7</manvolnum>
48 <refname>kernel-command-line
</refname>
49 <refpurpose>Kernel command line parameters
</refpurpose>
53 <para><filename>/proc/cmdline
</filename></para>
57 <title>Description
</title>
59 <para>The kernel, the initial RAM disk (initrd) and
60 basic userspace functionality may be configured at boot via
61 kernel command line arguments.
</para>
63 <para>For command line parameters understood by the kernel, please
65 <ulink url=
"https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html
</filename></ulink>
67 <citerefentry project='man-pages'
><refentrytitle>bootparam
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para>
69 <para>For command line parameters understood by the initial RAM
71 <citerefentry project='man-pages'
><refentrytitle>dracut.cmdline
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
72 or the documentation of the specific initrd implementation of your
77 <title>Core OS Command Line Arguments
</title>
79 <variablelist class='kernel-commandline-options'
>
81 <term><varname>systemd.unit=
</varname></term>
82 <term><varname>rd.systemd.unit=
</varname></term>
83 <term><varname>systemd.dump_core
</varname></term>
84 <term><varname>systemd.crash_chvt
</varname></term>
85 <term><varname>systemd.crash_shell
</varname></term>
86 <term><varname>systemd.crash_reboot
</varname></term>
87 <term><varname>systemd.confirm_spawn
</varname></term>
88 <term><varname>systemd.service_watchdogs
</varname></term>
89 <term><varname>systemd.show_status
</varname></term>
90 <term><varname>systemd.log_target=
</varname></term>
91 <term><varname>systemd.log_level=
</varname></term>
92 <term><varname>systemd.log_location=
</varname></term>
93 <term><varname>systemd.log_color
</varname></term>
94 <term><varname>systemd.default_standard_output=
</varname></term>
95 <term><varname>systemd.default_standard_error=
</varname></term>
96 <term><varname>systemd.setenv=
</varname></term>
97 <term><varname>systemd.machine_id=
</varname></term>
98 <term><varname>systemd.unified_cgroup_hierarchy
</varname></term>
99 <term><varname>systemd.legacy_systemd_cgroup_controller
</varname></term>
101 <para>Parameters understood by the system and service
102 manager to control system behavior. For details, see
103 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
108 <term><varname>systemd.mask=
</varname></term>
109 <term><varname>systemd.wants=
</varname></term>
110 <term><varname>systemd.debug_shell
</varname></term>
112 <para>Additional parameters understood by
113 <citerefentry><refentrytitle>systemd-debug-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
114 to mask or start specific units at boot, or invoke a debug
115 shell on tty9.
</para>
120 <term><varname>systemd.restore_state=
</varname></term>
122 <para>This parameter is understood by several system tools
123 to control whether or not they should restore system state
124 from the previous boot. For details, see
125 <citerefentry><refentrytitle>systemd-backlight@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
127 <citerefentry><refentrytitle>systemd-rfkill.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
133 <term><varname>systemd.volatile=
</varname></term>
135 <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
136 the special value
<literal>state
</literal>. If false (the default), normal boot mode is selected, the root
137 directory and
<filename>/var
</filename> are mounted as specified on the kernel command line or
138 <filename>/etc/fstab
</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
139 this case the root directory is mounted as volatile memory file system (
<literal>tmpfs
</literal>), and only
140 <filename>/usr
</filename> is mounted from the file system configured as root device, in read-only mode. This
141 enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
142 configuration and no stored state in effect, as
<filename>/etc
</filename> and
<filename>/var
</filename> (as
143 well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
144 setting is set to
<literal>state
</literal> the root file system is mounted as usual, however
145 <filename>/var
</filename> is mounted as a volatile memory file system (
<literal>tmpfs
</literal>), so that the
146 system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
148 <citerefentry><refentrytitle>systemd-volatile-root.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
150 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
155 <term><varname>quiet
</varname></term>
157 <para>Parameter understood by both the kernel and the system
158 and service manager to control console log verbosity. For
160 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
165 <term><varname>debug
</varname></term>
167 <para>Parameter understood by both the kernel and the system
168 and service manager to control console log verbosity. For
170 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
175 <term><varname>-b
</varname></term>
176 <term><varname>rd.emergency
</varname></term>
177 <term><varname>emergency
</varname></term>
178 <term><varname>rd.rescue
</varname></term>
179 <term><varname>rescue
</varname></term>
180 <term><varname>single
</varname></term>
181 <term><varname>s
</varname></term>
182 <term><varname>S
</varname></term>
183 <term><varname>1</varname></term>
184 <term><varname>2</varname></term>
185 <term><varname>3</varname></term>
186 <term><varname>4</varname></term>
187 <term><varname>5</varname></term>
189 <para>Parameters understood by the system and service
190 manager, as compatibility and convenience options. For details, see
191 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
196 <term><varname>locale.LANG=
</varname></term>
197 <term><varname>locale.LANGUAGE=
</varname></term>
198 <term><varname>locale.LC_CTYPE=
</varname></term>
199 <term><varname>locale.LC_NUMERIC=
</varname></term>
200 <term><varname>locale.LC_TIME=
</varname></term>
201 <term><varname>locale.LC_COLLATE=
</varname></term>
202 <term><varname>locale.LC_MONETARY=
</varname></term>
203 <term><varname>locale.LC_MESSAGES=
</varname></term>
204 <term><varname>locale.LC_PAPER=
</varname></term>
205 <term><varname>locale.LC_NAME=
</varname></term>
206 <term><varname>locale.LC_ADDRESS=
</varname></term>
207 <term><varname>locale.LC_TELEPHONE=
</varname></term>
208 <term><varname>locale.LC_MEASUREMENT=
</varname></term>
209 <term><varname>locale.LC_IDENTIFICATION=
</varname></term>
211 <para>Parameters understood by the system and service
212 manager to control locale and language settings. For
214 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
219 <term><varname>fsck.mode=
</varname></term>
220 <term><varname>fsck.repair=
</varname></term>
223 <para>Parameters understood by the file system checker
224 services. For details, see
225 <citerefentry><refentrytitle>systemd-fsck@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
230 <term><varname>quotacheck.mode=
</varname></term>
233 <para>Parameter understood by the file quota checker
234 service. For details, see
235 <citerefentry><refentrytitle>systemd-quotacheck.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
240 <term><varname>systemd.journald.forward_to_syslog=
</varname></term>
241 <term><varname>systemd.journald.forward_to_kmsg=
</varname></term>
242 <term><varname>systemd.journald.forward_to_console=
</varname></term>
243 <term><varname>systemd.journald.forward_to_wall=
</varname></term>
246 <para>Parameters understood by the journal service. For
248 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
253 <term><varname>vconsole.keymap=
</varname></term>
254 <term><varname>vconsole.keymap_toggle=
</varname></term>
255 <term><varname>vconsole.font=
</varname></term>
256 <term><varname>vconsole.font_map=
</varname></term>
257 <term><varname>vconsole.font_unimap=
</varname></term>
260 <para>Parameters understood by the virtual console setup logic. For details, see
261 <citerefentry><refentrytitle>vconsole.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
266 <term><varname>udev.log_priority=
</varname></term>
267 <term><varname>rd.udev.log_priority=
</varname></term>
268 <term><varname>udev.children_max=
</varname></term>
269 <term><varname>rd.udev.children_max=
</varname></term>
270 <term><varname>udev.exec_delay=
</varname></term>
271 <term><varname>rd.udev.exec_delay=
</varname></term>
272 <term><varname>udev.event_timeout=
</varname></term>
273 <term><varname>rd.udev.event_timeout=
</varname></term>
274 <term><varname>net.ifnames=
</varname></term>
277 <para>Parameters understood by the device event managing
278 daemon. For details, see
279 <citerefentry><refentrytitle>systemd-udevd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
284 <term><varname>plymouth.enable=
</varname></term>
287 <para>May be used to disable the Plymouth boot splash. For
289 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
294 <term><varname>luks=
</varname></term>
295 <term><varname>rd.luks=
</varname></term>
296 <term><varname>luks.crypttab=
</varname></term>
297 <term><varname>rd.luks.crypttab=
</varname></term>
298 <term><varname>luks.name=
</varname></term>
299 <term><varname>rd.luks.name=
</varname></term>
300 <term><varname>luks.uuid=
</varname></term>
301 <term><varname>rd.luks.uuid=
</varname></term>
302 <term><varname>luks.options=
</varname></term>
303 <term><varname>rd.luks.options=
</varname></term>
304 <term><varname>luks.key=
</varname></term>
305 <term><varname>rd.luks.key=
</varname></term>
308 <para>Configures the LUKS full-disk encryption logic at
309 boot. For details, see
310 <citerefentry><refentrytitle>systemd-cryptsetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
315 <term><varname>fstab=
</varname></term>
316 <term><varname>rd.fstab=
</varname></term>
319 <para>Configures the
<filename>/etc/fstab
</filename> logic
320 at boot. For details, see
321 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
326 <term><varname>root=
</varname></term>
327 <term><varname>rootfstype=
</varname></term>
328 <term><varname>rootflags=
</varname></term>
329 <term><varname>ro
</varname></term>
330 <term><varname>rw
</varname></term>
333 <para>Configures the root file system and its file system
334 type and mount options, as well as whether it shall be
335 mounted read-only or read-writable initially. For details,
337 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
342 <term><varname>mount.usr=
</varname></term>
343 <term><varname>mount.usrfstype=
</varname></term>
344 <term><varname>mount.usrflags=
</varname></term>
347 <para>Configures the /usr file system (if required) and
348 its file system type and mount options. For details, see
349 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
354 <term><varname>roothash=
</varname></term>
355 <term><varname>systemd.verity=
</varname></term>
356 <term><varname>rd.systemd.verity=
</varname></term>
357 <term><varname>systemd.verity_root_data=
</varname></term>
358 <term><varname>systemd.verity_root_hash=
</varname></term>
360 <para>Configures the integrity protection root hash for the root file system, and other related
361 parameters. For details, see
362 <citerefentry><refentrytitle>systemd-veritysetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
367 <term><varname>systemd.gpt_auto=
</varname></term>
368 <term><varname>rd.systemd.gpt_auto=
</varname></term>
371 <para>Configures whether GPT based partition auto-discovery
372 shall be attempted. For details, see
373 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
378 <term><varname>systemd.default_timeout_start_sec=
</varname></term>
381 <para>Overwrites the default start job timeout
<varname>DefaultTimeoutStartSec=
</varname> at boot. For details,
382 see
<citerefentry><refentrytitle>systemd-system.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
387 <term><varname>systemd.watchdog_device=
</varname></term>
390 <para>Overwrites the watchdog device path
<varname>WatchdogDevice=
</varname>. For details, see
391 <citerefentry><refentrytitle>systemd-system.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
396 <term><varname>modules_load=
</varname></term>
397 <term><varname>rd.modules_load=
</varname></term>
400 <para>Load a specific kernel module early at boot. For
402 <citerefentry><refentrytitle>systemd-modules-load.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
407 <term><varname>resume=
</varname></term>
410 <para>Enables resume from hibernation using the specified
412 <citerefentry project='man-pages'
><refentrytitle>fstab
</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
413 paths are supported. For details, see
414 <citerefentry><refentrytitle>systemd-hibernate-resume-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
419 <term><varname>systemd.firstboot=
</varname></term>
421 <listitem><para>Takes a boolean argument, defaults to on. If off,
422 <citerefentry><refentrytitle>systemd-firstboot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
423 will not query the user for basic system settings, even if the system boots up for the first time and the
424 relevant settings are not initialized yet.
</para></listitem>
431 <title>See Also
</title>
433 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
434 <citerefentry project='man-pages'
><refentrytitle>bootparam
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
435 <citerefentry project='man-pages'
><refentrytitle>dracut.cmdline
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
436 <citerefentry><refentrytitle>systemd-debug-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
437 <citerefentry><refentrytitle>systemd-fsck@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
438 <citerefentry><refentrytitle>systemd-quotacheck.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
439 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
440 <citerefentry><refentrytitle>systemd-vconsole-setup.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
441 <citerefentry><refentrytitle>systemd-udevd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
442 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
443 <citerefentry><refentrytitle>systemd-cryptsetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
444 <citerefentry><refentrytitle>systemd-veritysetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
445 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
446 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
447 <citerefentry><refentrytitle>systemd-volatile-root.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
448 <citerefentry><refentrytitle>systemd-modules-load.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
449 <citerefentry><refentrytitle>systemd-backlight@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
450 <citerefentry><refentrytitle>systemd-rfkill.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
451 <citerefentry><refentrytitle>systemd-hibernate-resume-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
452 <citerefentry><refentrytitle>systemd-firstboot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>