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.show_status
</varname></term>
89 <term><varname>systemd.log_target=
</varname></term>
90 <term><varname>systemd.log_level=
</varname></term>
91 <term><varname>systemd.log_location=
</varname></term>
92 <term><varname>systemd.log_color
</varname></term>
93 <term><varname>systemd.default_standard_output=
</varname></term>
94 <term><varname>systemd.default_standard_error=
</varname></term>
95 <term><varname>systemd.setenv=
</varname></term>
96 <term><varname>systemd.machine_id=
</varname></term>
97 <term><varname>systemd.unified_cgroup_hierarchy
</varname></term>
98 <term><varname>systemd.legacy_systemd_cgroup_controller
</varname></term>
100 <para>Parameters understood by the system and service
101 manager to control system behavior. For details, see
102 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
107 <term><varname>systemd.mask=
</varname></term>
108 <term><varname>systemd.wants=
</varname></term>
109 <term><varname>systemd.debug_shell
</varname></term>
111 <para>Additional parameters understood by
112 <citerefentry><refentrytitle>systemd-debug-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
113 to mask or start specific units at boot, or invoke a debug
114 shell on tty9.
</para>
119 <term><varname>systemd.restore_state=
</varname></term>
121 <para>This parameter is understood by several system tools
122 to control whether or not they should restore system state
123 from the previous boot. For details, see
124 <citerefentry><refentrytitle>systemd-backlight@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
126 <citerefentry><refentrytitle>systemd-rfkill.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
132 <term><varname>systemd.volatile=
</varname></term>
134 <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
135 the special value
<literal>state
</literal>. If false (the default), normal boot mode is selected, the root
136 directory and
<filename>/var
</filename> are mounted as specified on the kernel command line or
137 <filename>/etc/fstab
</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
138 this case the root directory is mounted as volatile memory file system (
<literal>tmpfs
</literal>), and only
139 <filename>/usr
</filename> is mounted from the file system configured as root device, in read-only mode. This
140 enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
141 configuration and no stored state in effect, as
<filename>/etc
</filename> and
<filename>/var
</filename> (as
142 well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
143 setting is set to
<literal>state
</literal> the root file system is mounted as usual, however
144 <filename>/var
</filename> is mounted as a volatile memory file system (
<literal>tmpfs
</literal>), so that the
145 system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
147 <citerefentry><refentrytitle>systemd-volatile-root.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
149 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
154 <term><varname>quiet
</varname></term>
156 <para>Parameter understood by both the kernel and the system
157 and service manager to control console log verbosity. For
159 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
164 <term><varname>debug
</varname></term>
166 <para>Parameter understood by both the kernel and the system
167 and service manager to control console log verbosity. For
169 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
174 <term><varname>-b
</varname></term>
175 <term><varname>rd.emergency
</varname></term>
176 <term><varname>emergency
</varname></term>
177 <term><varname>rd.rescue
</varname></term>
178 <term><varname>rescue
</varname></term>
179 <term><varname>single
</varname></term>
180 <term><varname>s
</varname></term>
181 <term><varname>S
</varname></term>
182 <term><varname>1</varname></term>
183 <term><varname>2</varname></term>
184 <term><varname>3</varname></term>
185 <term><varname>4</varname></term>
186 <term><varname>5</varname></term>
188 <para>Parameters understood by the system and service
189 manager, as compatibility and convenience options. For details, see
190 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
195 <term><varname>locale.LANG=
</varname></term>
196 <term><varname>locale.LANGUAGE=
</varname></term>
197 <term><varname>locale.LC_CTYPE=
</varname></term>
198 <term><varname>locale.LC_NUMERIC=
</varname></term>
199 <term><varname>locale.LC_TIME=
</varname></term>
200 <term><varname>locale.LC_COLLATE=
</varname></term>
201 <term><varname>locale.LC_MONETARY=
</varname></term>
202 <term><varname>locale.LC_MESSAGES=
</varname></term>
203 <term><varname>locale.LC_PAPER=
</varname></term>
204 <term><varname>locale.LC_NAME=
</varname></term>
205 <term><varname>locale.LC_ADDRESS=
</varname></term>
206 <term><varname>locale.LC_TELEPHONE=
</varname></term>
207 <term><varname>locale.LC_MEASUREMENT=
</varname></term>
208 <term><varname>locale.LC_IDENTIFICATION=
</varname></term>
210 <para>Parameters understood by the system and service
211 manager to control locale and language settings. For
213 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
218 <term><varname>fsck.mode=
</varname></term>
219 <term><varname>fsck.repair=
</varname></term>
222 <para>Parameters understood by the file system checker
223 services. For details, see
224 <citerefentry><refentrytitle>systemd-fsck@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
229 <term><varname>quotacheck.mode=
</varname></term>
232 <para>Parameter understood by the file quota checker
233 service. For details, see
234 <citerefentry><refentrytitle>systemd-quotacheck.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
239 <term><varname>systemd.journald.forward_to_syslog=
</varname></term>
240 <term><varname>systemd.journald.forward_to_kmsg=
</varname></term>
241 <term><varname>systemd.journald.forward_to_console=
</varname></term>
242 <term><varname>systemd.journald.forward_to_wall=
</varname></term>
245 <para>Parameters understood by the journal service. For
247 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
252 <term><varname>vconsole.keymap=
</varname></term>
253 <term><varname>vconsole.keymap_toggle=
</varname></term>
254 <term><varname>vconsole.font=
</varname></term>
255 <term><varname>vconsole.font_map=
</varname></term>
256 <term><varname>vconsole.font_unimap=
</varname></term>
259 <para>Parameters understood by the virtual console setup logic. For details, see
260 <citerefentry><refentrytitle>vconsole.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
265 <term><varname>udev.log_priority=
</varname></term>
266 <term><varname>rd.udev.log_priority=
</varname></term>
267 <term><varname>udev.children_max=
</varname></term>
268 <term><varname>rd.udev.children_max=
</varname></term>
269 <term><varname>udev.exec_delay=
</varname></term>
270 <term><varname>rd.udev.exec_delay=
</varname></term>
271 <term><varname>udev.event_timeout=
</varname></term>
272 <term><varname>rd.udev.event_timeout=
</varname></term>
273 <term><varname>net.ifnames=
</varname></term>
276 <para>Parameters understood by the device event managing
277 daemon. For details, see
278 <citerefentry><refentrytitle>systemd-udevd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
283 <term><varname>plymouth.enable=
</varname></term>
286 <para>May be used to disable the Plymouth boot splash. For
288 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
293 <term><varname>luks=
</varname></term>
294 <term><varname>rd.luks=
</varname></term>
295 <term><varname>luks.crypttab=
</varname></term>
296 <term><varname>rd.luks.crypttab=
</varname></term>
297 <term><varname>luks.name=
</varname></term>
298 <term><varname>rd.luks.name=
</varname></term>
299 <term><varname>luks.uuid=
</varname></term>
300 <term><varname>rd.luks.uuid=
</varname></term>
301 <term><varname>luks.options=
</varname></term>
302 <term><varname>rd.luks.options=
</varname></term>
303 <term><varname>luks.key=
</varname></term>
304 <term><varname>rd.luks.key=
</varname></term>
307 <para>Configures the LUKS full-disk encryption logic at
308 boot. For details, see
309 <citerefentry><refentrytitle>systemd-cryptsetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
314 <term><varname>fstab=
</varname></term>
315 <term><varname>rd.fstab=
</varname></term>
318 <para>Configures the
<filename>/etc/fstab
</filename> logic
319 at boot. For details, see
320 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
325 <term><varname>root=
</varname></term>
326 <term><varname>rootfstype=
</varname></term>
327 <term><varname>rootflags=
</varname></term>
328 <term><varname>ro
</varname></term>
329 <term><varname>rw
</varname></term>
332 <para>Configures the root file system and its file system
333 type and mount options, as well as whether it shall be
334 mounted read-only or read-writable initially. For details,
336 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
341 <term><varname>mount.usr=
</varname></term>
342 <term><varname>mount.usrfstype=
</varname></term>
343 <term><varname>mount.usrflags=
</varname></term>
346 <para>Configures the /usr file system (if required) and
347 its file system type and mount options. For details, see
348 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
353 <term><varname>roothash=
</varname></term>
354 <term><varname>systemd.verity=
</varname></term>
355 <term><varname>rd.systemd.verity=
</varname></term>
356 <term><varname>systemd.verity_root_data=
</varname></term>
357 <term><varname>systemd.verity_root_hash=
</varname></term>
359 <para>Configures the integrity protection root hash for the root file system, and other related
360 parameters. For details, see
361 <citerefentry><refentrytitle>systemd-veritysetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
366 <term><varname>systemd.gpt_auto=
</varname></term>
367 <term><varname>rd.systemd.gpt_auto=
</varname></term>
370 <para>Configures whether GPT based partition auto-discovery
371 shall be attempted. For details, see
372 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
377 <term><varname>systemd.default_timeout_start_sec=
</varname></term>
380 <para>Overwrites the default start job timeout
<varname>DefaultTimeoutStartSec=
</varname> at boot. For details,
381 see
<citerefentry><refentrytitle>systemd-system.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
386 <term><varname>modules_load=
</varname></term>
387 <term><varname>rd.modules_load=
</varname></term>
390 <para>Load a specific kernel module early at boot. For
392 <citerefentry><refentrytitle>systemd-modules-load.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
397 <term><varname>resume=
</varname></term>
400 <para>Enables resume from hibernation using the specified
402 <citerefentry project='man-pages'
><refentrytitle>fstab
</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
403 paths are supported. For details, see
404 <citerefentry><refentrytitle>systemd-hibernate-resume-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
409 <term><varname>systemd.firstboot=
</varname></term>
411 <listitem><para>Takes a boolean argument, defaults to on. If off,
412 <citerefentry><refentrytitle>systemd-firstboot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
413 will not query the user for basic system settings, even if the system boots up for the first time and the
414 relevant settings are not initialized yet.
</para></listitem>
421 <title>See Also
</title>
423 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
424 <citerefentry project='man-pages'
><refentrytitle>bootparam
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
425 <citerefentry project='man-pages'
><refentrytitle>dracut.cmdline
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
426 <citerefentry><refentrytitle>systemd-debug-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
427 <citerefentry><refentrytitle>systemd-fsck@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
428 <citerefentry><refentrytitle>systemd-quotacheck.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
429 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
430 <citerefentry><refentrytitle>systemd-vconsole-setup.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
431 <citerefentry><refentrytitle>systemd-udevd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
432 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
433 <citerefentry><refentrytitle>systemd-cryptsetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
434 <citerefentry><refentrytitle>systemd-veritysetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
435 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
436 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
437 <citerefentry><refentrytitle>systemd-volatile-root.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
438 <citerefentry><refentrytitle>systemd-modules-load.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
439 <citerefentry><refentrytitle>systemd-backlight@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
440 <citerefentry><refentrytitle>systemd-rfkill.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
441 <citerefentry><refentrytitle>systemd-hibernate-resume-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
442 <citerefentry><refentrytitle>systemd-firstboot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>