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1<?xml version='1.0'?> <!--*-nxml-*-->
2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
12b42c76 3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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4
5<!--
6 This file is part of systemd.
7
8 Copyright 2012 Lennart Poettering
9
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.
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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.
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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/>.
22-->
23
24<refentry id="kernel-command-line">
25
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26 <refentryinfo>
27 <title>kernel-command-line</title>
28 <productname>systemd</productname>
29
30 <authorgroup>
31 <author>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
36 </author>
37 </authorgroup>
38 </refentryinfo>
39
40 <refmeta>
41 <refentrytitle>kernel-command-line</refentrytitle>
42 <manvolnum>7</manvolnum>
43 </refmeta>
44
45 <refnamediv>
46 <refname>kernel-command-line</refname>
47 <refpurpose>Kernel command line parameters</refpurpose>
48 </refnamediv>
49
50 <refsynopsisdiv>
51 <para><filename>/proc/cmdline</filename></para>
52 </refsynopsisdiv>
53
54 <refsect1>
55 <title>Description</title>
56
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>
60
61 <para>For command line parameters understood by the kernel, please
62 see <ulink
63 url="https://www.kernel.org/doc/Documentation/kernel-parameters.txt"><filename>kernel-parameters.txt</filename></ulink>
64 and
65 <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
66
67 <para>For command line parameters understood by the initial RAM
68 disk, please see
af105d03 69 <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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70 or the documentation of the specific initrd implementation of your
71 installation.</para>
72 </refsect1>
73
74 <refsect1>
75 <title>Core OS Command Line Arguments</title>
76
77 <variablelist class='kernel-commandline-options'>
78 <varlistentry>
79 <term><varname>systemd.unit=</varname></term>
80 <term><varname>rd.systemd.unit=</varname></term>
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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>
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87 <term><varname>systemd.log_target=</varname></term>
88 <term><varname>systemd.log_level=</varname></term>
798d3a52 89 <term><varname>systemd.log_location=</varname></term>
770c4777 90 <term><varname>systemd.log_color</varname></term>
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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>
ee48dbd5 94 <term><varname>systemd.machine_id=</varname></term>
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95 <term><varname>systemd.unified_cgroup_hierarchy</varname></term>
96 <term><varname>systemd.legacy_systemd_cgroup_controller</varname></term>
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97 <listitem>
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>
101 </listitem>
102 </varlistentry>
103
104 <varlistentry>
105 <term><varname>systemd.mask=</varname></term>
106 <term><varname>systemd.wants=</varname></term>
1d84ad94 107 <term><varname>systemd.debug_shell</varname></term>
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108 <listitem>
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>
113 </listitem>
114 </varlistentry>
115
116 <varlistentry>
117 <term><varname>systemd.restore_state=</varname></term>
118 <listitem>
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>
123 and
af105d03 124 <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
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125 </para>
126 </listitem>
127 </varlistentry>
128
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129 <varlistentry>
130 <term><varname>systemd.volatile=</varname></term>
131 <listitem>
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,
144 see
145 <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
146 and
147 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
148 </listitem>
149 </varlistentry>
150
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151 <varlistentry>
152 <term><varname>quiet</varname></term>
153 <listitem>
154 <para>Parameter understood by both the kernel and the system
155 and service manager to control console log verbosity. For
156 details, see
157 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
158 </listitem>
159 </varlistentry>
160
161 <varlistentry>
162 <term><varname>debug</varname></term>
163 <listitem>
164 <para>Parameter understood by both the kernel and the system
165 and service manager to control console log verbosity. For
166 details, see
167 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
168 </listitem>
169 </varlistentry>
170
171 <varlistentry>
172 <term><varname>-b</varname></term>
dcd61450 173 <term><varname>rd.emergency</varname></term>
798d3a52 174 <term><varname>emergency</varname></term>
dcd61450 175 <term><varname>rd.rescue</varname></term>
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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>
185 <listitem>
186 <para>Parameters understood by the system and service
dcd61450 187 manager, as compatibility and convenience options. For details, see
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188 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
189 </listitem>
190 </varlistentry>
191
192 <varlistentry>
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>
207 <listitem>
208 <para>Parameters understood by the system and service
209 manager to control locale and language settings. For
210 details, see
211 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
212 </listitem>
213 </varlistentry>
214
215 <varlistentry>
216 <term><varname>fsck.mode=</varname></term>
217 <term><varname>fsck.repair=</varname></term>
218
219 <listitem>
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>
223 </listitem>
224 </varlistentry>
225
226 <varlistentry>
227 <term><varname>quotacheck.mode=</varname></term>
228
229 <listitem>
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>
233 </listitem>
234 </varlistentry>
235
236 <varlistentry>
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>
241
242 <listitem>
243 <para>Parameters understood by the journal service. For
244 details, see
245 <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
246 </listitem>
247 </varlistentry>
248
249 <varlistentry>
250 <term><varname>vconsole.keymap=</varname></term>
72ccee50 251 <term><varname>vconsole.keymap_toggle=</varname></term>
798d3a52 252 <term><varname>vconsole.font=</varname></term>
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253 <term><varname>vconsole.font_map=</varname></term>
254 <term><varname>vconsole.font_unimap=</varname></term>
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255
256 <listitem>
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257 <para>Parameters understood by the virtual console setup logic. For details, see
258 <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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259 </listitem>
260 </varlistentry>
261
262 <varlistentry>
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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>
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271 <term><varname>net.ifnames=</varname></term>
272
273 <listitem>
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>
277 </listitem>
278 </varlistentry>
279
280 <varlistentry>
281 <term><varname>plymouth.enable=</varname></term>
282
283 <listitem>
284 <para>May be used to disable the Plymouth boot splash. For
285 details, see
286 <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
287 </listitem>
288 </varlistentry>
289
290 <varlistentry>
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>
303
304 <listitem>
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>
308 </listitem>
309 </varlistentry>
310
311 <varlistentry>
312 <term><varname>fstab=</varname></term>
313 <term><varname>rd.fstab=</varname></term>
314
315 <listitem>
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>
319 </listitem>
320 </varlistentry>
321
322 <varlistentry>
323 <term><varname>root=</varname></term>
324 <term><varname>rootfstype=</varname></term>
d6a12e7c 325 <term><varname>rootflags=</varname></term>
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326 <term><varname>ro</varname></term>
327 <term><varname>rw</varname></term>
328
329 <listitem>
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,
333 see
334 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
335 </listitem>
336 </varlistentry>
337
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338 <varlistentry>
339 <term><varname>roothash=</varname></term>
340 <term><varname>systemd.verity=</varname></term>
341 <term><varname>rd.systemd.verity=</varname></term>
342 <term><varname>systemd.verity_root_data=</varname></term>
343 <term><varname>systemd.verity_root_hash=</varname></term>
344 <listitem>
345 <para>Configures the integrity protection root hash for the root file system, and other related
346 parameters. For details, see
347 <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
348 </listitem>
349 </varlistentry>
350
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351 <varlistentry>
352 <term><varname>systemd.gpt_auto=</varname></term>
353 <term><varname>rd.systemd.gpt_auto=</varname></term>
354
355 <listitem>
356 <para>Configures whether GPT based partition auto-discovery
357 shall be attempted. For details, see
358 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
359 </listitem>
360 </varlistentry>
361
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362 <varlistentry>
363 <term><varname>systemd.default_timeout_start_sec=</varname></term>
364
365 <listitem>
366 <para>Overwrites the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at boot. For details,
367 see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
368 </listitem>
369 </varlistentry>
370
798d3a52 371 <varlistentry>
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372 <term><varname>modules_load=</varname></term>
373 <term><varname>rd.modules_load=</varname></term>
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374
375 <listitem>
376 <para>Load a specific kernel module early at boot. For
377 details, see
378 <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
379 </listitem>
380 </varlistentry>
381
382 <varlistentry>
383 <term><varname>resume=</varname></term>
384
385 <listitem>
386 <para>Enables resume from hibernation using the specified
387 device. All
3ba3a79d 388 <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
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389 paths are supported. For details, see
390 <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
391 </listitem>
392 </varlistentry>
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393
394 <varlistentry>
395 <term><varname>systemd.firstboot=</varname></term>
396
397 <listitem><para>Takes a boolean argument, defaults to on. If off,
398 <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
399 will not query the user for basic system settings, even if the system boots up for the first time and the
400 relevant settings are not initialized yet.</para></listitem>
401 </varlistentry>
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402 </variablelist>
403
404 </refsect1>
405
406 <refsect1>
407 <title>See Also</title>
408 <para>
409 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
410 <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
af105d03 411 <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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412 <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
413 <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
414 <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
415 <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
416 <citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
417 <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
418 <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
419 <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
2f3dfc6f 420 <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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421 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
422 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
91214a37 423 <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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424 <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
425 <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
af105d03 426 <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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427 <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
428 <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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429 </para>
430 </refsect1>
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431
432</refentry>