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+
9 <refentry id=
"kernel-command-line">
12 <title>kernel-command-line
</title>
13 <productname>systemd
</productname>
17 <refentrytitle>kernel-command-line
</refentrytitle>
18 <manvolnum>7</manvolnum>
22 <refname>kernel-command-line
</refname>
23 <refpurpose>Kernel command line parameters
</refpurpose>
27 <para><filename>/proc/cmdline
</filename></para>
31 <title>Description
</title>
33 <para>The kernel, the initial RAM disk (initrd) and
34 basic userspace functionality may be configured at boot via
35 kernel command line arguments.
</para>
37 <para>For command line parameters understood by the kernel, please
39 <ulink url=
"https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html
</filename></ulink>
41 <citerefentry project='man-pages'
><refentrytitle>bootparam
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para>
43 <para>For command line parameters understood by the initial RAM
45 <citerefentry project='man-pages'
><refentrytitle>dracut.cmdline
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
46 or the documentation of the specific initrd implementation of your
51 <title>Core OS Command Line Arguments
</title>
53 <variablelist class='kernel-commandline-options'
>
55 <term><varname>systemd.unit=
</varname></term>
56 <term><varname>rd.systemd.unit=
</varname></term>
57 <term><varname>systemd.dump_core
</varname></term>
58 <term><varname>systemd.crash_chvt
</varname></term>
59 <term><varname>systemd.crash_shell
</varname></term>
60 <term><varname>systemd.crash_reboot
</varname></term>
61 <term><varname>systemd.confirm_spawn
</varname></term>
62 <term><varname>systemd.service_watchdogs
</varname></term>
63 <term><varname>systemd.show_status
</varname></term>
64 <term><varname>systemd.log_target=
</varname></term>
65 <term><varname>systemd.log_level=
</varname></term>
66 <term><varname>systemd.log_location=
</varname></term>
67 <term><varname>systemd.log_color
</varname></term>
68 <term><varname>systemd.default_standard_output=
</varname></term>
69 <term><varname>systemd.default_standard_error=
</varname></term>
70 <term><varname>systemd.setenv=
</varname></term>
71 <term><varname>systemd.machine_id=
</varname></term>
72 <term><varname>systemd.unified_cgroup_hierarchy
</varname></term>
73 <term><varname>systemd.legacy_systemd_cgroup_controller
</varname></term>
75 <para>Parameters understood by the system and service
76 manager to control system behavior. For details, see
77 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
82 <term><varname>systemd.mask=
</varname></term>
83 <term><varname>systemd.wants=
</varname></term>
84 <term><varname>systemd.debug_shell
</varname></term>
86 <para>Additional parameters understood by
87 <citerefentry><refentrytitle>systemd-debug-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
88 to mask or start specific units at boot, or invoke a debug
94 <term><varname>systemd.restore_state=
</varname></term>
96 <para>This parameter is understood by several system tools
97 to control whether or not they should restore system state
98 from the previous boot. For details, see
99 <citerefentry><refentrytitle>systemd-backlight@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
101 <citerefentry><refentrytitle>systemd-rfkill.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
107 <term><varname>systemd.volatile=
</varname></term>
109 <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
110 the special value
<literal>state
</literal>. If false (the default), normal boot mode is selected, the root
111 directory and
<filename>/var
</filename> are mounted as specified on the kernel command line or
112 <filename>/etc/fstab
</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
113 this case the root directory is mounted as volatile memory file system (
<literal>tmpfs
</literal>), and only
114 <filename>/usr
</filename> is mounted from the file system configured as root device, in read-only mode. This
115 enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
116 configuration and no stored state in effect, as
<filename>/etc
</filename> and
<filename>/var
</filename> (as
117 well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
118 setting is set to
<literal>state
</literal> the root file system is mounted as usual, however
119 <filename>/var
</filename> is mounted as a volatile memory file system (
<literal>tmpfs
</literal>), so that the
120 system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
122 <citerefentry><refentrytitle>systemd-volatile-root.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
124 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
129 <term><varname>quiet
</varname></term>
131 <para>Parameter understood by both the kernel and the system
132 and service manager to control console log verbosity. For
134 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
139 <term><varname>debug
</varname></term>
141 <para>Parameter understood by both the kernel and the system
142 and service manager to control console log verbosity. For
144 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
149 <term><varname>-b
</varname></term>
150 <term><varname>rd.emergency
</varname></term>
151 <term><varname>emergency
</varname></term>
152 <term><varname>rd.rescue
</varname></term>
153 <term><varname>rescue
</varname></term>
154 <term><varname>single
</varname></term>
155 <term><varname>s
</varname></term>
156 <term><varname>S
</varname></term>
157 <term><varname>1</varname></term>
158 <term><varname>2</varname></term>
159 <term><varname>3</varname></term>
160 <term><varname>4</varname></term>
161 <term><varname>5</varname></term>
163 <para>Parameters understood by the system and service
164 manager, as compatibility and convenience options. For details, see
165 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
170 <term><varname>locale.LANG=
</varname></term>
171 <term><varname>locale.LANGUAGE=
</varname></term>
172 <term><varname>locale.LC_CTYPE=
</varname></term>
173 <term><varname>locale.LC_NUMERIC=
</varname></term>
174 <term><varname>locale.LC_TIME=
</varname></term>
175 <term><varname>locale.LC_COLLATE=
</varname></term>
176 <term><varname>locale.LC_MONETARY=
</varname></term>
177 <term><varname>locale.LC_MESSAGES=
</varname></term>
178 <term><varname>locale.LC_PAPER=
</varname></term>
179 <term><varname>locale.LC_NAME=
</varname></term>
180 <term><varname>locale.LC_ADDRESS=
</varname></term>
181 <term><varname>locale.LC_TELEPHONE=
</varname></term>
182 <term><varname>locale.LC_MEASUREMENT=
</varname></term>
183 <term><varname>locale.LC_IDENTIFICATION=
</varname></term>
185 <para>Parameters understood by the system and service
186 manager to control locale and language settings. For
188 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
193 <term><varname>fsck.mode=
</varname></term>
194 <term><varname>fsck.repair=
</varname></term>
197 <para>Parameters understood by the file system checker
198 services. For details, see
199 <citerefentry><refentrytitle>systemd-fsck@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
204 <term><varname>quotacheck.mode=
</varname></term>
207 <para>Parameter understood by the file quota checker
208 service. For details, see
209 <citerefentry><refentrytitle>systemd-quotacheck.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
214 <term><varname>systemd.journald.forward_to_syslog=
</varname></term>
215 <term><varname>systemd.journald.forward_to_kmsg=
</varname></term>
216 <term><varname>systemd.journald.forward_to_console=
</varname></term>
217 <term><varname>systemd.journald.forward_to_wall=
</varname></term>
220 <para>Parameters understood by the journal service. For
222 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
227 <term><varname>vconsole.keymap=
</varname></term>
228 <term><varname>vconsole.keymap_toggle=
</varname></term>
229 <term><varname>vconsole.font=
</varname></term>
230 <term><varname>vconsole.font_map=
</varname></term>
231 <term><varname>vconsole.font_unimap=
</varname></term>
234 <para>Parameters understood by the virtual console setup logic. For details, see
235 <citerefentry><refentrytitle>vconsole.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
240 <term><varname>udev.log_priority=
</varname></term>
241 <term><varname>rd.udev.log_priority=
</varname></term>
242 <term><varname>udev.children_max=
</varname></term>
243 <term><varname>rd.udev.children_max=
</varname></term>
244 <term><varname>udev.exec_delay=
</varname></term>
245 <term><varname>rd.udev.exec_delay=
</varname></term>
246 <term><varname>udev.event_timeout=
</varname></term>
247 <term><varname>rd.udev.event_timeout=
</varname></term>
248 <term><varname>net.ifnames=
</varname></term>
251 <para>Parameters understood by the device event managing
252 daemon. For details, see
253 <citerefentry><refentrytitle>systemd-udevd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
258 <term><varname>plymouth.enable=
</varname></term>
261 <para>May be used to disable the Plymouth boot splash. For
263 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
268 <term><varname>luks=
</varname></term>
269 <term><varname>rd.luks=
</varname></term>
270 <term><varname>luks.crypttab=
</varname></term>
271 <term><varname>rd.luks.crypttab=
</varname></term>
272 <term><varname>luks.name=
</varname></term>
273 <term><varname>rd.luks.name=
</varname></term>
274 <term><varname>luks.uuid=
</varname></term>
275 <term><varname>rd.luks.uuid=
</varname></term>
276 <term><varname>luks.options=
</varname></term>
277 <term><varname>rd.luks.options=
</varname></term>
278 <term><varname>luks.key=
</varname></term>
279 <term><varname>rd.luks.key=
</varname></term>
282 <para>Configures the LUKS full-disk encryption logic at
283 boot. For details, see
284 <citerefentry><refentrytitle>systemd-cryptsetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
289 <term><varname>fstab=
</varname></term>
290 <term><varname>rd.fstab=
</varname></term>
293 <para>Configures the
<filename>/etc/fstab
</filename> logic
294 at boot. For details, see
295 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
300 <term><varname>root=
</varname></term>
301 <term><varname>rootfstype=
</varname></term>
302 <term><varname>rootflags=
</varname></term>
303 <term><varname>ro
</varname></term>
304 <term><varname>rw
</varname></term>
307 <para>Configures the root file system and its file system
308 type and mount options, as well as whether it shall be
309 mounted read-only or read-writable initially. For details,
311 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
316 <term><varname>mount.usr=
</varname></term>
317 <term><varname>mount.usrfstype=
</varname></term>
318 <term><varname>mount.usrflags=
</varname></term>
321 <para>Configures the /usr file system (if required) and
322 its file system type and mount options. For details, see
323 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
328 <term><varname>roothash=
</varname></term>
329 <term><varname>systemd.verity=
</varname></term>
330 <term><varname>rd.systemd.verity=
</varname></term>
331 <term><varname>systemd.verity_root_data=
</varname></term>
332 <term><varname>systemd.verity_root_hash=
</varname></term>
334 <para>Configures the integrity protection root hash for the root file system, and other related
335 parameters. For details, see
336 <citerefentry><refentrytitle>systemd-veritysetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
341 <term><varname>systemd.gpt_auto=
</varname></term>
342 <term><varname>rd.systemd.gpt_auto=
</varname></term>
345 <para>Configures whether GPT based partition auto-discovery
346 shall be attempted. For details, see
347 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
352 <term><varname>systemd.default_timeout_start_sec=
</varname></term>
355 <para>Overwrites the default start job timeout
<varname>DefaultTimeoutStartSec=
</varname> at boot. For details,
356 see
<citerefentry><refentrytitle>systemd-system.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
361 <term><varname>systemd.watchdog_device=
</varname></term>
364 <para>Overwrites the watchdog device path
<varname>WatchdogDevice=
</varname>. For details, see
365 <citerefentry><refentrytitle>systemd-system.conf
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
</para>
370 <term><varname>modules_load=
</varname></term>
371 <term><varname>rd.modules_load=
</varname></term>
374 <para>Load a specific kernel module early at boot. For
376 <citerefentry><refentrytitle>systemd-modules-load.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
381 <term><varname>resume=
</varname></term>
384 <para>Enables resume from hibernation using the specified
386 <citerefentry project='man-pages'
><refentrytitle>fstab
</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
387 paths are supported. For details, see
388 <citerefentry><refentrytitle>systemd-hibernate-resume-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
</para>
393 <term><varname>systemd.firstboot=
</varname></term>
395 <listitem><para>Takes a boolean argument, defaults to on. If off,
396 <citerefentry><refentrytitle>systemd-firstboot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
397 will not query the user for basic system settings, even if the system boots up for the first time and the
398 relevant settings are not initialized yet.
</para></listitem>
405 <title>See Also
</title>
407 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
408 <citerefentry project='man-pages'
><refentrytitle>bootparam
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
409 <citerefentry project='man-pages'
><refentrytitle>dracut.cmdline
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
410 <citerefentry><refentrytitle>systemd-debug-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
411 <citerefentry><refentrytitle>systemd-fsck@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
412 <citerefentry><refentrytitle>systemd-quotacheck.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
413 <citerefentry><refentrytitle>systemd-journald.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
414 <citerefentry><refentrytitle>systemd-vconsole-setup.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
415 <citerefentry><refentrytitle>systemd-udevd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
416 <citerefentry project='die-net'
><refentrytitle>plymouth
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
417 <citerefentry><refentrytitle>systemd-cryptsetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
418 <citerefentry><refentrytitle>systemd-veritysetup-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
419 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
420 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
421 <citerefentry><refentrytitle>systemd-volatile-root.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
422 <citerefentry><refentrytitle>systemd-modules-load.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
423 <citerefentry><refentrytitle>systemd-backlight@.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
424 <citerefentry><refentrytitle>systemd-rfkill.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
425 <citerefentry><refentrytitle>systemd-hibernate-resume-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
426 <citerefentry><refentrytitle>systemd-firstboot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>