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 This file is part of systemd.
8 Copyright 2012 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
15 systemd is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public License
21 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id=
"kernel-command-line">
27 <title>kernel-command-line
</title>
28 <productname>systemd
</productname>
32 <contrib>Developer
</contrib>
33 <firstname>Lennart
</firstname>
34 <surname>Poettering
</surname>
35 <email>lennart@poettering.net
</email>
41 <refentrytitle>kernel-command-line
</refentrytitle>
42 <manvolnum>7</manvolnum>
46 <refname>kernel-command-line
</refname>
47 <refpurpose>Kernel command line parameters
</refpurpose>
51 <para><filename>/proc/cmdline
</filename></para>
55 <title>Description
</title>
57 <para>The kernel, the initial RAM disk (initrd) and
58 basic userspace functionality may be configured at boot via
59 kernel command line arguments.
</para>
61 <para>For command line parameters understood by the kernel, please
63 <ulink url=
"https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html
</filename></ulink>
65 <citerefentry project='man-pages'
><refentrytitle>bootparam
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para>
67 <para>For command line parameters understood by the initial RAM
69 <citerefentry project='man-pages'
><refentrytitle>dracut.cmdline
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
70 or the documentation of the specific initrd implementation of your
75 <title>Core OS Command Line Arguments
</title>
77 <variablelist class='kernel-commandline-options'
>
79 <term><varname>systemd.unit=
</varname></term>
80 <term><varname>rd.systemd.unit=
</varname></term>
81 <term><varname>systemd.dump_core
</varname></term>
82 <term><varname>systemd.crash_chvt
</varname></term>
83 <term><varname>systemd.crash_shell
</varname></term>
84 <term><varname>systemd.crash_reboot
</varname></term>
85 <term><varname>systemd.confirm_spawn
</varname></term>
86 <term><varname>systemd.show_status
</varname></term>
87 <term><varname>systemd.log_target=
</varname></term>
88 <term><varname>systemd.log_level=
</varname></term>
89 <term><varname>systemd.log_location=
</varname></term>
90 <term><varname>systemd.log_color
</varname></term>
91 <term><varname>systemd.default_standard_output=
</varname></term>
92 <term><varname>systemd.default_standard_error=
</varname></term>
93 <term><varname>systemd.setenv=
</varname></term>
94 <term><varname>systemd.machine_id=
</varname></term>
95 <term><varname>systemd.unified_cgroup_hierarchy
</varname></term>
96 <term><varname>systemd.legacy_systemd_cgroup_controller
</varname></term>
98 <para>Parameters understood by the system and service
99 manager to control system behavior. For details, see
100 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
105 <term><varname>systemd.mask=
</varname></term>
106 <term><varname>systemd.wants=
</varname></term>
107 <term><varname>systemd.debug_shell
</varname></term>
109 <para>Additional parameters understood by
110 <citerefentry><refentrytitle>systemd-debug-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
111 to mask or start specific units at boot, or invoke a debug
112 shell on tty9.
</para>
117 <term><varname>systemd.restore_state=
</varname></term>
119 <para>This parameter is understood by several system tools
120 to control whether or not they should restore system state
121 from the previous boot. For details, see
122 <citerefentry><refentrytitle>systemd-backlight@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
124 <citerefentry><refentrytitle>systemd-rfkill.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
130 <term><varname>systemd.volatile=
</varname></term>
132 <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
133 the special value
<literal>state
</literal>. If false (the default), normal boot mode is selected, the root
134 directory and
<filename>/var
</filename> are mounted as specified on the kernel command line or
135 <filename>/etc/fstab
</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
136 this case the root directory is mounted as volatile memory file system (
<literal>tmpfs
</literal>), and only
137 <filename>/usr
</filename> is mounted from the file system configured as root device, in read-only mode. This
138 enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
139 configuration and no stored state in effect, as
<filename>/etc
</filename> and
<filename>/var
</filename> (as
140 well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
141 setting is set to
<literal>state
</literal> the root file system is mounted as usual, however
142 <filename>/var
</filename> is mounted as a volatile memory file system (
<literal>tmpfs
</literal>), so that the
143 system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
145 <citerefentry><refentrytitle>systemd-volatile-root.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
147 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
152 <term><varname>quiet
</varname></term>
154 <para>Parameter understood by both the kernel and the system
155 and service manager to control console log verbosity. For
157 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
162 <term><varname>debug
</varname></term>
164 <para>Parameter understood by both the kernel and the system
165 and service manager to control console log verbosity. For
167 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
172 <term><varname>-b
</varname></term>
173 <term><varname>rd.emergency
</varname></term>
174 <term><varname>emergency
</varname></term>
175 <term><varname>rd.rescue
</varname></term>
176 <term><varname>rescue
</varname></term>
177 <term><varname>single
</varname></term>
178 <term><varname>s
</varname></term>
179 <term><varname>S
</varname></term>
180 <term><varname>1</varname></term>
181 <term><varname>2</varname></term>
182 <term><varname>3</varname></term>
183 <term><varname>4</varname></term>
184 <term><varname>5</varname></term>
186 <para>Parameters understood by the system and service
187 manager, as compatibility and convenience options. For details, see
188 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
193 <term><varname>locale.LANG=
</varname></term>
194 <term><varname>locale.LANGUAGE=
</varname></term>
195 <term><varname>locale.LC_CTYPE=
</varname></term>
196 <term><varname>locale.LC_NUMERIC=
</varname></term>
197 <term><varname>locale.LC_TIME=
</varname></term>
198 <term><varname>locale.LC_COLLATE=
</varname></term>
199 <term><varname>locale.LC_MONETARY=
</varname></term>
200 <term><varname>locale.LC_MESSAGES=
</varname></term>
201 <term><varname>locale.LC_PAPER=
</varname></term>
202 <term><varname>locale.LC_NAME=
</varname></term>
203 <term><varname>locale.LC_ADDRESS=
</varname></term>
204 <term><varname>locale.LC_TELEPHONE=
</varname></term>
205 <term><varname>locale.LC_MEASUREMENT=
</varname></term>
206 <term><varname>locale.LC_IDENTIFICATION=
</varname></term>
208 <para>Parameters understood by the system and service
209 manager to control locale and language settings. For
211 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
216 <term><varname>fsck.mode=
</varname></term>
217 <term><varname>fsck.repair=
</varname></term>
220 <para>Parameters understood by the file system checker
221 services. For details, see
222 <citerefentry><refentrytitle>systemd-fsck@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
227 <term><varname>quotacheck.mode=
</varname></term>
230 <para>Parameter understood by the file quota checker
231 service. For details, see
232 <citerefentry><refentrytitle>systemd-quotacheck.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
237 <term><varname>systemd.journald.forward_to_syslog=
</varname></term>
238 <term><varname>systemd.journald.forward_to_kmsg=
</varname></term>
239 <term><varname>systemd.journald.forward_to_console=
</varname></term>
240 <term><varname>systemd.journald.forward_to_wall=
</varname></term>
243 <para>Parameters understood by the journal service. For
245 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
250 <term><varname>vconsole.keymap=
</varname></term>
251 <term><varname>vconsole.keymap_toggle=
</varname></term>
252 <term><varname>vconsole.font=
</varname></term>
253 <term><varname>vconsole.font_map=
</varname></term>
254 <term><varname>vconsole.font_unimap=
</varname></term>
257 <para>Parameters understood by the virtual console setup logic. For details, see
258 <citerefentry><refentrytitle>vconsole.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
263 <term><varname>udev.log_priority=
</varname></term>
264 <term><varname>rd.udev.log_priority=
</varname></term>
265 <term><varname>udev.children_max=
</varname></term>
266 <term><varname>rd.udev.children_max=
</varname></term>
267 <term><varname>udev.exec_delay=
</varname></term>
268 <term><varname>rd.udev.exec_delay=
</varname></term>
269 <term><varname>udev.event_timeout=
</varname></term>
270 <term><varname>rd.udev.event_timeout=
</varname></term>
271 <term><varname>net.ifnames=
</varname></term>
274 <para>Parameters understood by the device event managing
275 daemon. For details, see
276 <citerefentry><refentrytitle>systemd-udevd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
281 <term><varname>plymouth.enable=
</varname></term>
284 <para>May be used to disable the Plymouth boot splash. For
286 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
291 <term><varname>luks=
</varname></term>
292 <term><varname>rd.luks=
</varname></term>
293 <term><varname>luks.crypttab=
</varname></term>
294 <term><varname>rd.luks.crypttab=
</varname></term>
295 <term><varname>luks.name=
</varname></term>
296 <term><varname>rd.luks.name=
</varname></term>
297 <term><varname>luks.uuid=
</varname></term>
298 <term><varname>rd.luks.uuid=
</varname></term>
299 <term><varname>luks.options=
</varname></term>
300 <term><varname>rd.luks.options=
</varname></term>
301 <term><varname>luks.key=
</varname></term>
302 <term><varname>rd.luks.key=
</varname></term>
305 <para>Configures the LUKS full-disk encryption logic at
306 boot. For details, see
307 <citerefentry><refentrytitle>systemd-cryptsetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
312 <term><varname>fstab=
</varname></term>
313 <term><varname>rd.fstab=
</varname></term>
316 <para>Configures the
<filename>/etc/fstab
</filename> logic
317 at boot. For details, see
318 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
323 <term><varname>root=
</varname></term>
324 <term><varname>rootfstype=
</varname></term>
325 <term><varname>rootflags=
</varname></term>
326 <term><varname>ro
</varname></term>
327 <term><varname>rw
</varname></term>
330 <para>Configures the root file system and its file system
331 type and mount options, as well as whether it shall be
332 mounted read-only or read-writable initially. For details,
334 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
339 <term><varname>mount.usr=
</varname></term>
340 <term><varname>mount.usrfstype=
</varname></term>
341 <term><varname>mount.usrflags=
</varname></term>
344 <para>Configures the /usr file system (if required) and
345 its file system type and mount options. For details, see
346 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
351 <term><varname>roothash=
</varname></term>
352 <term><varname>systemd.verity=
</varname></term>
353 <term><varname>rd.systemd.verity=
</varname></term>
354 <term><varname>systemd.verity_root_data=
</varname></term>
355 <term><varname>systemd.verity_root_hash=
</varname></term>
357 <para>Configures the integrity protection root hash for the root file system, and other related
358 parameters. For details, see
359 <citerefentry><refentrytitle>systemd-veritysetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
364 <term><varname>systemd.gpt_auto=
</varname></term>
365 <term><varname>rd.systemd.gpt_auto=
</varname></term>
368 <para>Configures whether GPT based partition auto-discovery
369 shall be attempted. For details, see
370 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
375 <term><varname>systemd.default_timeout_start_sec=
</varname></term>
378 <para>Overwrites the default start job timeout
<varname>DefaultTimeoutStartSec=
</varname> at boot. For details,
379 see
<citerefentry><refentrytitle>systemd-system.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
384 <term><varname>modules_load=
</varname></term>
385 <term><varname>rd.modules_load=
</varname></term>
388 <para>Load a specific kernel module early at boot. For
390 <citerefentry><refentrytitle>systemd-modules-load.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
395 <term><varname>resume=
</varname></term>
398 <para>Enables resume from hibernation using the specified
400 <citerefentry project='man-pages'
><refentrytitle>fstab
</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
401 paths are supported. For details, see
402 <citerefentry><refentrytitle>systemd-hibernate-resume-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
407 <term><varname>systemd.firstboot=
</varname></term>
409 <listitem><para>Takes a boolean argument, defaults to on. If off,
410 <citerefentry><refentrytitle>systemd-firstboot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
411 will not query the user for basic system settings, even if the system boots up for the first time and the
412 relevant settings are not initialized yet.
</para></listitem>
419 <title>See Also
</title>
421 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
422 <citerefentry project='man-pages'
><refentrytitle>bootparam
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
423 <citerefentry project='man-pages'
><refentrytitle>dracut.cmdline
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
424 <citerefentry><refentrytitle>systemd-debug-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
425 <citerefentry><refentrytitle>systemd-fsck@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
426 <citerefentry><refentrytitle>systemd-quotacheck.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
427 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
428 <citerefentry><refentrytitle>systemd-vconsole-setup.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
429 <citerefentry><refentrytitle>systemd-udevd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
430 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
431 <citerefentry><refentrytitle>systemd-cryptsetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
432 <citerefentry><refentrytitle>systemd-veritysetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
433 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
434 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
435 <citerefentry><refentrytitle>systemd-volatile-root.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
436 <citerefentry><refentrytitle>systemd-modules-load.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
437 <citerefentry><refentrytitle>systemd-backlight@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
438 <citerefentry><refentrytitle>systemd-rfkill.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
439 <citerefentry><refentrytitle>systemd-hibernate-resume-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
440 <citerefentry><refentrytitle>systemd-firstboot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>