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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>
81 <term><varname>systemd.dump_core=</varname></term>
798d3a52 82 <term><varname>systemd.crash_chvt=</varname></term>
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83 <term><varname>systemd.crash_shell=</varname></term>
84 <term><varname>systemd.crash_reboot=</varname></term>
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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_color=</varname></term>
90 <term><varname>systemd.log_location=</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>
ee48dbd5 94 <term><varname>systemd.machine_id=</varname></term>
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95 <listitem>
96 <para>Parameters understood by the system and service
97 manager to control system behavior. For details, see
98 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
99 </listitem>
100 </varlistentry>
101
102 <varlistentry>
103 <term><varname>systemd.mask=</varname></term>
104 <term><varname>systemd.wants=</varname></term>
1d84ad94 105 <term><varname>systemd.debug_shell</varname></term>
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106 <listitem>
107 <para>Additional parameters understood by
108 <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
109 to mask or start specific units at boot, or invoke a debug
110 shell on tty9.</para>
111 </listitem>
112 </varlistentry>
113
114 <varlistentry>
115 <term><varname>systemd.restore_state=</varname></term>
116 <listitem>
117 <para>This parameter is understood by several system tools
118 to control whether or not they should restore system state
119 from the previous boot. For details, see
120 <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
121 and
af105d03 122 <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
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123 </para>
124 </listitem>
125 </varlistentry>
126
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127 <varlistentry>
128 <term><varname>systemd.volatile=</varname></term>
129 <listitem>
130 <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
131 the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root
132 directory and <filename>/var</filename> are mounted as specified on the kernel command line or
133 <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
134 this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only
135 <filename>/usr</filename> is mounted from the file system configured as root device, in read-only mode. This
136 enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
137 configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as
138 well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
139 setting is set to <literal>state</literal> the root file system is mounted as usual, however
140 <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
141 system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
142 see
143 <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
144 and
145 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
146 </listitem>
147 </varlistentry>
148
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149 <varlistentry>
150 <term><varname>quiet</varname></term>
151 <listitem>
152 <para>Parameter understood by both the kernel and the system
153 and service manager to control console log verbosity. For
154 details, see
155 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
156 </listitem>
157 </varlistentry>
158
159 <varlistentry>
160 <term><varname>debug</varname></term>
161 <listitem>
162 <para>Parameter understood by both the kernel and the system
163 and service manager to control console log verbosity. For
164 details, see
165 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
166 </listitem>
167 </varlistentry>
168
169 <varlistentry>
170 <term><varname>-b</varname></term>
dcd61450 171 <term><varname>rd.emergency</varname></term>
798d3a52 172 <term><varname>emergency</varname></term>
dcd61450 173 <term><varname>rd.rescue</varname></term>
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174 <term><varname>rescue</varname></term>
175 <term><varname>single</varname></term>
176 <term><varname>s</varname></term>
177 <term><varname>S</varname></term>
178 <term><varname>1</varname></term>
179 <term><varname>2</varname></term>
180 <term><varname>3</varname></term>
181 <term><varname>4</varname></term>
182 <term><varname>5</varname></term>
183 <listitem>
184 <para>Parameters understood by the system and service
dcd61450 185 manager, as compatibility and convenience options. For details, see
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186 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
187 </listitem>
188 </varlistentry>
189
190 <varlistentry>
191 <term><varname>locale.LANG=</varname></term>
192 <term><varname>locale.LANGUAGE=</varname></term>
193 <term><varname>locale.LC_CTYPE=</varname></term>
194 <term><varname>locale.LC_NUMERIC=</varname></term>
195 <term><varname>locale.LC_TIME=</varname></term>
196 <term><varname>locale.LC_COLLATE=</varname></term>
197 <term><varname>locale.LC_MONETARY=</varname></term>
198 <term><varname>locale.LC_MESSAGES=</varname></term>
199 <term><varname>locale.LC_PAPER=</varname></term>
200 <term><varname>locale.LC_NAME=</varname></term>
201 <term><varname>locale.LC_ADDRESS=</varname></term>
202 <term><varname>locale.LC_TELEPHONE=</varname></term>
203 <term><varname>locale.LC_MEASUREMENT=</varname></term>
204 <term><varname>locale.LC_IDENTIFICATION=</varname></term>
205 <listitem>
206 <para>Parameters understood by the system and service
207 manager to control locale and language settings. For
208 details, see
209 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
210 </listitem>
211 </varlistentry>
212
213 <varlistentry>
214 <term><varname>fsck.mode=</varname></term>
215 <term><varname>fsck.repair=</varname></term>
216
217 <listitem>
218 <para>Parameters understood by the file system checker
219 services. For details, see
220 <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
221 </listitem>
222 </varlistentry>
223
224 <varlistentry>
225 <term><varname>quotacheck.mode=</varname></term>
226
227 <listitem>
228 <para>Parameter understood by the file quota checker
229 service. For details, see
230 <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
231 </listitem>
232 </varlistentry>
233
234 <varlistentry>
235 <term><varname>systemd.journald.forward_to_syslog=</varname></term>
236 <term><varname>systemd.journald.forward_to_kmsg=</varname></term>
237 <term><varname>systemd.journald.forward_to_console=</varname></term>
238 <term><varname>systemd.journald.forward_to_wall=</varname></term>
239
240 <listitem>
241 <para>Parameters understood by the journal service. For
242 details, see
243 <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
244 </listitem>
245 </varlistentry>
246
247 <varlistentry>
248 <term><varname>vconsole.keymap=</varname></term>
72ccee50 249 <term><varname>vconsole.keymap_toggle=</varname></term>
798d3a52 250 <term><varname>vconsole.font=</varname></term>
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251 <term><varname>vconsole.font_map=</varname></term>
252 <term><varname>vconsole.font_unimap=</varname></term>
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253
254 <listitem>
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255 <para>Parameters understood by the virtual console setup logic. For details, see
256 <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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257 </listitem>
258 </varlistentry>
259
260 <varlistentry>
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261 <term><varname>udev.log_priority=</varname></term>
262 <term><varname>rd.udev.log_priority=</varname></term>
263 <term><varname>udev.children_max=</varname></term>
264 <term><varname>rd.udev.children_max=</varname></term>
265 <term><varname>udev.exec_delay=</varname></term>
266 <term><varname>rd.udev.exec_delay=</varname></term>
267 <term><varname>udev.event_timeout=</varname></term>
268 <term><varname>rd.udev.event_timeout=</varname></term>
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269 <term><varname>net.ifnames=</varname></term>
270
271 <listitem>
272 <para>Parameters understood by the device event managing
273 daemon. For details, see
274 <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
275 </listitem>
276 </varlistentry>
277
278 <varlistentry>
279 <term><varname>plymouth.enable=</varname></term>
280
281 <listitem>
282 <para>May be used to disable the Plymouth boot splash. For
283 details, see
284 <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
285 </listitem>
286 </varlistentry>
287
288 <varlistentry>
289 <term><varname>luks=</varname></term>
290 <term><varname>rd.luks=</varname></term>
291 <term><varname>luks.crypttab=</varname></term>
292 <term><varname>rd.luks.crypttab=</varname></term>
293 <term><varname>luks.name=</varname></term>
294 <term><varname>rd.luks.name=</varname></term>
295 <term><varname>luks.uuid=</varname></term>
296 <term><varname>rd.luks.uuid=</varname></term>
297 <term><varname>luks.options=</varname></term>
298 <term><varname>rd.luks.options=</varname></term>
299 <term><varname>luks.key=</varname></term>
300 <term><varname>rd.luks.key=</varname></term>
301
302 <listitem>
303 <para>Configures the LUKS full-disk encryption logic at
304 boot. For details, see
305 <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
306 </listitem>
307 </varlistentry>
308
309 <varlistentry>
310 <term><varname>fstab=</varname></term>
311 <term><varname>rd.fstab=</varname></term>
312
313 <listitem>
314 <para>Configures the <filename>/etc/fstab</filename> logic
315 at boot. For details, see
316 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
317 </listitem>
318 </varlistentry>
319
320 <varlistentry>
321 <term><varname>root=</varname></term>
322 <term><varname>rootfstype=</varname></term>
d6a12e7c 323 <term><varname>rootflags=</varname></term>
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324 <term><varname>ro</varname></term>
325 <term><varname>rw</varname></term>
326
327 <listitem>
328 <para>Configures the root file system and its file system
329 type and mount options, as well as whether it shall be
330 mounted read-only or read-writable initially. For details,
331 see
332 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
333 </listitem>
334 </varlistentry>
335
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336 <varlistentry>
337 <term><varname>roothash=</varname></term>
338 <term><varname>systemd.verity=</varname></term>
339 <term><varname>rd.systemd.verity=</varname></term>
340 <term><varname>systemd.verity_root_data=</varname></term>
341 <term><varname>systemd.verity_root_hash=</varname></term>
342 <listitem>
343 <para>Configures the integrity protection root hash for the root file system, and other related
344 parameters. For details, see
345 <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
346 </listitem>
347 </varlistentry>
348
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349 <varlistentry>
350 <term><varname>systemd.gpt_auto=</varname></term>
351 <term><varname>rd.systemd.gpt_auto=</varname></term>
352
353 <listitem>
354 <para>Configures whether GPT based partition auto-discovery
355 shall be attempted. For details, see
356 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
357 </listitem>
358 </varlistentry>
359
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360 <varlistentry>
361 <term><varname>systemd.default_timeout_start_sec=</varname></term>
362
363 <listitem>
364 <para>Overwrites the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at boot. For details,
365 see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
366 </listitem>
367 </varlistentry>
368
798d3a52 369 <varlistentry>
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370 <term><varname>modules_load=</varname></term>
371 <term><varname>rd.modules_load=</varname></term>
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372
373 <listitem>
374 <para>Load a specific kernel module early at boot. For
375 details, see
376 <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
377 </listitem>
378 </varlistentry>
379
380 <varlistentry>
381 <term><varname>resume=</varname></term>
382
383 <listitem>
384 <para>Enables resume from hibernation using the specified
385 device. All
3ba3a79d 386 <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
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387 paths are supported. For details, see
388 <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
389 </listitem>
390 </varlistentry>
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391
392 <varlistentry>
393 <term><varname>systemd.firstboot=</varname></term>
394
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>
399 </varlistentry>
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400 </variablelist>
401
402 </refsect1>
403
404 <refsect1>
405 <title>See Also</title>
406 <para>
407 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
408 <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
af105d03 409 <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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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>,
2f3dfc6f 418 <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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419 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
420 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
91214a37 421 <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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422 <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
423 <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
af105d03 424 <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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425 <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
426 <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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427 </para>
428 </refsect1>
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429
430</refentry>