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
13 <refentry id=
"kernel-command-line">
16 <title>kernel-command-line
</title>
17 <productname>systemd
</productname>
21 <contrib>Developer
</contrib>
22 <firstname>Lennart
</firstname>
23 <surname>Poettering
</surname>
24 <email>lennart@poettering.net
</email>
30 <refentrytitle>kernel-command-line
</refentrytitle>
31 <manvolnum>7</manvolnum>
35 <refname>kernel-command-line
</refname>
36 <refpurpose>Kernel command line parameters
</refpurpose>
40 <para><filename>/proc/cmdline
</filename></para>
44 <title>Description
</title>
46 <para>The kernel, the initial RAM disk (initrd) and
47 basic userspace functionality may be configured at boot via
48 kernel command line arguments.
</para>
50 <para>For command line parameters understood by the kernel, please
52 <ulink url=
"https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html
</filename></ulink>
54 <citerefentry project='man-pages'
><refentrytitle>bootparam
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para>
56 <para>For command line parameters understood by the initial RAM
58 <citerefentry project='man-pages'
><refentrytitle>dracut.cmdline
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
59 or the documentation of the specific initrd implementation of your
64 <title>Core OS Command Line Arguments
</title>
66 <variablelist class='kernel-commandline-options'
>
68 <term><varname>systemd.unit=
</varname></term>
69 <term><varname>rd.systemd.unit=
</varname></term>
70 <term><varname>systemd.dump_core
</varname></term>
71 <term><varname>systemd.crash_chvt
</varname></term>
72 <term><varname>systemd.crash_shell
</varname></term>
73 <term><varname>systemd.crash_reboot
</varname></term>
74 <term><varname>systemd.confirm_spawn
</varname></term>
75 <term><varname>systemd.service_watchdogs
</varname></term>
76 <term><varname>systemd.show_status
</varname></term>
77 <term><varname>systemd.log_target=
</varname></term>
78 <term><varname>systemd.log_level=
</varname></term>
79 <term><varname>systemd.log_location=
</varname></term>
80 <term><varname>systemd.log_color
</varname></term>
81 <term><varname>systemd.default_standard_output=
</varname></term>
82 <term><varname>systemd.default_standard_error=
</varname></term>
83 <term><varname>systemd.setenv=
</varname></term>
84 <term><varname>systemd.machine_id=
</varname></term>
85 <term><varname>systemd.unified_cgroup_hierarchy
</varname></term>
86 <term><varname>systemd.legacy_systemd_cgroup_controller
</varname></term>
88 <para>Parameters understood by the system and service
89 manager to control system behavior. For details, see
90 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
95 <term><varname>systemd.mask=
</varname></term>
96 <term><varname>systemd.wants=
</varname></term>
97 <term><varname>systemd.debug_shell
</varname></term>
99 <para>Additional parameters understood by
100 <citerefentry><refentrytitle>systemd-debug-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
101 to mask or start specific units at boot, or invoke a debug
102 shell on tty9.
</para>
107 <term><varname>systemd.restore_state=
</varname></term>
109 <para>This parameter is understood by several system tools
110 to control whether or not they should restore system state
111 from the previous boot. For details, see
112 <citerefentry><refentrytitle>systemd-backlight@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
114 <citerefentry><refentrytitle>systemd-rfkill.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
120 <term><varname>systemd.volatile=
</varname></term>
122 <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
123 the special value
<literal>state
</literal>. If false (the default), normal boot mode is selected, the root
124 directory and
<filename>/var
</filename> are mounted as specified on the kernel command line or
125 <filename>/etc/fstab
</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
126 this case the root directory is mounted as volatile memory file system (
<literal>tmpfs
</literal>), and only
127 <filename>/usr
</filename> is mounted from the file system configured as root device, in read-only mode. This
128 enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
129 configuration and no stored state in effect, as
<filename>/etc
</filename> and
<filename>/var
</filename> (as
130 well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
131 setting is set to
<literal>state
</literal> the root file system is mounted as usual, however
132 <filename>/var
</filename> is mounted as a volatile memory file system (
<literal>tmpfs
</literal>), so that the
133 system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
135 <citerefentry><refentrytitle>systemd-volatile-root.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
137 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
142 <term><varname>quiet
</varname></term>
144 <para>Parameter understood by both the kernel and the system
145 and service manager to control console log verbosity. For
147 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
152 <term><varname>debug
</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>-b
</varname></term>
163 <term><varname>rd.emergency
</varname></term>
164 <term><varname>emergency
</varname></term>
165 <term><varname>rd.rescue
</varname></term>
166 <term><varname>rescue
</varname></term>
167 <term><varname>single
</varname></term>
168 <term><varname>s
</varname></term>
169 <term><varname>S
</varname></term>
170 <term><varname>1</varname></term>
171 <term><varname>2</varname></term>
172 <term><varname>3</varname></term>
173 <term><varname>4</varname></term>
174 <term><varname>5</varname></term>
176 <para>Parameters understood by the system and service
177 manager, as compatibility and convenience options. For details, see
178 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
183 <term><varname>locale.LANG=
</varname></term>
184 <term><varname>locale.LANGUAGE=
</varname></term>
185 <term><varname>locale.LC_CTYPE=
</varname></term>
186 <term><varname>locale.LC_NUMERIC=
</varname></term>
187 <term><varname>locale.LC_TIME=
</varname></term>
188 <term><varname>locale.LC_COLLATE=
</varname></term>
189 <term><varname>locale.LC_MONETARY=
</varname></term>
190 <term><varname>locale.LC_MESSAGES=
</varname></term>
191 <term><varname>locale.LC_PAPER=
</varname></term>
192 <term><varname>locale.LC_NAME=
</varname></term>
193 <term><varname>locale.LC_ADDRESS=
</varname></term>
194 <term><varname>locale.LC_TELEPHONE=
</varname></term>
195 <term><varname>locale.LC_MEASUREMENT=
</varname></term>
196 <term><varname>locale.LC_IDENTIFICATION=
</varname></term>
198 <para>Parameters understood by the system and service
199 manager to control locale and language settings. For
201 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
206 <term><varname>fsck.mode=
</varname></term>
207 <term><varname>fsck.repair=
</varname></term>
210 <para>Parameters understood by the file system checker
211 services. For details, see
212 <citerefentry><refentrytitle>systemd-fsck@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
217 <term><varname>quotacheck.mode=
</varname></term>
220 <para>Parameter understood by the file quota checker
221 service. For details, see
222 <citerefentry><refentrytitle>systemd-quotacheck.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
227 <term><varname>systemd.journald.forward_to_syslog=
</varname></term>
228 <term><varname>systemd.journald.forward_to_kmsg=
</varname></term>
229 <term><varname>systemd.journald.forward_to_console=
</varname></term>
230 <term><varname>systemd.journald.forward_to_wall=
</varname></term>
233 <para>Parameters understood by the journal service. For
235 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
240 <term><varname>vconsole.keymap=
</varname></term>
241 <term><varname>vconsole.keymap_toggle=
</varname></term>
242 <term><varname>vconsole.font=
</varname></term>
243 <term><varname>vconsole.font_map=
</varname></term>
244 <term><varname>vconsole.font_unimap=
</varname></term>
247 <para>Parameters understood by the virtual console setup logic. For details, see
248 <citerefentry><refentrytitle>vconsole.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
253 <term><varname>udev.log_priority=
</varname></term>
254 <term><varname>rd.udev.log_priority=
</varname></term>
255 <term><varname>udev.children_max=
</varname></term>
256 <term><varname>rd.udev.children_max=
</varname></term>
257 <term><varname>udev.exec_delay=
</varname></term>
258 <term><varname>rd.udev.exec_delay=
</varname></term>
259 <term><varname>udev.event_timeout=
</varname></term>
260 <term><varname>rd.udev.event_timeout=
</varname></term>
261 <term><varname>net.ifnames=
</varname></term>
264 <para>Parameters understood by the device event managing
265 daemon. For details, see
266 <citerefentry><refentrytitle>systemd-udevd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
271 <term><varname>plymouth.enable=
</varname></term>
274 <para>May be used to disable the Plymouth boot splash. For
276 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
281 <term><varname>luks=
</varname></term>
282 <term><varname>rd.luks=
</varname></term>
283 <term><varname>luks.crypttab=
</varname></term>
284 <term><varname>rd.luks.crypttab=
</varname></term>
285 <term><varname>luks.name=
</varname></term>
286 <term><varname>rd.luks.name=
</varname></term>
287 <term><varname>luks.uuid=
</varname></term>
288 <term><varname>rd.luks.uuid=
</varname></term>
289 <term><varname>luks.options=
</varname></term>
290 <term><varname>rd.luks.options=
</varname></term>
291 <term><varname>luks.key=
</varname></term>
292 <term><varname>rd.luks.key=
</varname></term>
295 <para>Configures the LUKS full-disk encryption logic at
296 boot. For details, see
297 <citerefentry><refentrytitle>systemd-cryptsetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
302 <term><varname>fstab=
</varname></term>
303 <term><varname>rd.fstab=
</varname></term>
306 <para>Configures the
<filename>/etc/fstab
</filename> logic
307 at boot. For details, see
308 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
313 <term><varname>root=
</varname></term>
314 <term><varname>rootfstype=
</varname></term>
315 <term><varname>rootflags=
</varname></term>
316 <term><varname>ro
</varname></term>
317 <term><varname>rw
</varname></term>
320 <para>Configures the root file system and its file system
321 type and mount options, as well as whether it shall be
322 mounted read-only or read-writable initially. For details,
324 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
329 <term><varname>mount.usr=
</varname></term>
330 <term><varname>mount.usrfstype=
</varname></term>
331 <term><varname>mount.usrflags=
</varname></term>
334 <para>Configures the /usr file system (if required) and
335 its file system type and mount options. For details, see
336 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
341 <term><varname>roothash=
</varname></term>
342 <term><varname>systemd.verity=
</varname></term>
343 <term><varname>rd.systemd.verity=
</varname></term>
344 <term><varname>systemd.verity_root_data=
</varname></term>
345 <term><varname>systemd.verity_root_hash=
</varname></term>
347 <para>Configures the integrity protection root hash for the root file system, and other related
348 parameters. For details, see
349 <citerefentry><refentrytitle>systemd-veritysetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
354 <term><varname>systemd.gpt_auto=
</varname></term>
355 <term><varname>rd.systemd.gpt_auto=
</varname></term>
358 <para>Configures whether GPT based partition auto-discovery
359 shall be attempted. For details, see
360 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
365 <term><varname>systemd.default_timeout_start_sec=
</varname></term>
368 <para>Overwrites the default start job timeout
<varname>DefaultTimeoutStartSec=
</varname> at boot. For details,
369 see
<citerefentry><refentrytitle>systemd-system.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
374 <term><varname>systemd.watchdog_device=
</varname></term>
377 <para>Overwrites the watchdog device path
<varname>WatchdogDevice=
</varname>. For details, see
378 <citerefentry><refentrytitle>systemd-system.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
383 <term><varname>modules_load=
</varname></term>
384 <term><varname>rd.modules_load=
</varname></term>
387 <para>Load a specific kernel module early at boot. For
389 <citerefentry><refentrytitle>systemd-modules-load.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
394 <term><varname>resume=
</varname></term>
397 <para>Enables resume from hibernation using the specified
399 <citerefentry project='man-pages'
><refentrytitle>fstab
</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
400 paths are supported. For details, see
401 <citerefentry><refentrytitle>systemd-hibernate-resume-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
406 <term><varname>systemd.firstboot=
</varname></term>
408 <listitem><para>Takes a boolean argument, defaults to on. If off,
409 <citerefentry><refentrytitle>systemd-firstboot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
410 will not query the user for basic system settings, even if the system boots up for the first time and the
411 relevant settings are not initialized yet.
</para></listitem>
418 <title>See Also
</title>
420 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
421 <citerefentry project='man-pages'
><refentrytitle>bootparam
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
422 <citerefentry project='man-pages'
><refentrytitle>dracut.cmdline
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
423 <citerefentry><refentrytitle>systemd-debug-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
424 <citerefentry><refentrytitle>systemd-fsck@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
425 <citerefentry><refentrytitle>systemd-quotacheck.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
426 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
427 <citerefentry><refentrytitle>systemd-vconsole-setup.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
428 <citerefentry><refentrytitle>systemd-udevd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
429 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
430 <citerefentry><refentrytitle>systemd-cryptsetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
431 <citerefentry><refentrytitle>systemd-veritysetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
432 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
433 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
434 <citerefentry><refentrytitle>systemd-volatile-root.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
435 <citerefentry><refentrytitle>systemd-modules-load.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
436 <citerefentry><refentrytitle>systemd-backlight@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
437 <citerefentry><refentrytitle>systemd-rfkill.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
438 <citerefentry><refentrytitle>systemd-hibernate-resume-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
439 <citerefentry><refentrytitle>systemd-firstboot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>