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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<!--
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6 SPDX-License-Identifier: LGPL-2.1+
7
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8 This file is part of systemd.
9
10 Copyright 2012 Lennart Poettering
11
12 systemd is free software; you can redistribute it and/or modify it
13 under the terms of the GNU Lesser General Public License as published by
14 the Free Software Foundation; either version 2.1 of the License, or
15 (at your option) any later version.
16
17 systemd is distributed in the hope that it will be useful, but
18 WITHOUT ANY WARRANTY; without even the implied warranty of
19 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20 Lesser General Public License for more details.
21
22 You should have received a copy of the GNU Lesser General Public License
23 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24-->
25
26<refentry id="kernel-command-line">
27
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28 <refentryinfo>
29 <title>kernel-command-line</title>
30 <productname>systemd</productname>
31
32 <authorgroup>
33 <author>
34 <contrib>Developer</contrib>
35 <firstname>Lennart</firstname>
36 <surname>Poettering</surname>
37 <email>lennart@poettering.net</email>
38 </author>
39 </authorgroup>
40 </refentryinfo>
41
42 <refmeta>
43 <refentrytitle>kernel-command-line</refentrytitle>
44 <manvolnum>7</manvolnum>
45 </refmeta>
46
47 <refnamediv>
48 <refname>kernel-command-line</refname>
49 <refpurpose>Kernel command line parameters</refpurpose>
50 </refnamediv>
51
52 <refsynopsisdiv>
53 <para><filename>/proc/cmdline</filename></para>
54 </refsynopsisdiv>
55
56 <refsect1>
57 <title>Description</title>
58
59 <para>The kernel, the initial RAM disk (initrd) and
60 basic userspace functionality may be configured at boot via
61 kernel command line arguments.</para>
62
63 <para>For command line parameters understood by the kernel, please
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64 see
65 <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink>
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66 and
67 <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
68
69 <para>For command line parameters understood by the initial RAM
70 disk, please see
af105d03 71 <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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72 or the documentation of the specific initrd implementation of your
73 installation.</para>
74 </refsect1>
75
76 <refsect1>
77 <title>Core OS Command Line Arguments</title>
78
79 <variablelist class='kernel-commandline-options'>
80 <varlistentry>
81 <term><varname>systemd.unit=</varname></term>
82 <term><varname>rd.systemd.unit=</varname></term>
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83 <term><varname>systemd.dump_core</varname></term>
84 <term><varname>systemd.crash_chvt</varname></term>
85 <term><varname>systemd.crash_shell</varname></term>
86 <term><varname>systemd.crash_reboot</varname></term>
87 <term><varname>systemd.confirm_spawn</varname></term>
2a12e32e 88 <term><varname>systemd.service_watchdogs</varname></term>
770c4777 89 <term><varname>systemd.show_status</varname></term>
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90 <term><varname>systemd.log_target=</varname></term>
91 <term><varname>systemd.log_level=</varname></term>
798d3a52 92 <term><varname>systemd.log_location=</varname></term>
770c4777 93 <term><varname>systemd.log_color</varname></term>
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94 <term><varname>systemd.default_standard_output=</varname></term>
95 <term><varname>systemd.default_standard_error=</varname></term>
96 <term><varname>systemd.setenv=</varname></term>
ee48dbd5 97 <term><varname>systemd.machine_id=</varname></term>
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98 <term><varname>systemd.unified_cgroup_hierarchy</varname></term>
99 <term><varname>systemd.legacy_systemd_cgroup_controller</varname></term>
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100 <listitem>
101 <para>Parameters understood by the system and service
102 manager to control system behavior. For details, see
103 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
104 </listitem>
105 </varlistentry>
106
107 <varlistentry>
108 <term><varname>systemd.mask=</varname></term>
109 <term><varname>systemd.wants=</varname></term>
1d84ad94 110 <term><varname>systemd.debug_shell</varname></term>
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111 <listitem>
112 <para>Additional parameters understood by
113 <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
114 to mask or start specific units at boot, or invoke a debug
115 shell on tty9.</para>
116 </listitem>
117 </varlistentry>
118
119 <varlistentry>
120 <term><varname>systemd.restore_state=</varname></term>
121 <listitem>
122 <para>This parameter is understood by several system tools
123 to control whether or not they should restore system state
124 from the previous boot. For details, see
125 <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
126 and
af105d03 127 <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
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128 </para>
129 </listitem>
130 </varlistentry>
131
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132 <varlistentry>
133 <term><varname>systemd.volatile=</varname></term>
134 <listitem>
135 <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
136 the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root
137 directory and <filename>/var</filename> are mounted as specified on the kernel command line or
138 <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
139 this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only
140 <filename>/usr</filename> is mounted from the file system configured as root device, in read-only mode. This
141 enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
142 configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as
143 well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
144 setting is set to <literal>state</literal> the root file system is mounted as usual, however
145 <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
146 system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
147 see
148 <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
149 and
150 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
151 </listitem>
152 </varlistentry>
153
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154 <varlistentry>
155 <term><varname>quiet</varname></term>
156 <listitem>
157 <para>Parameter understood by both the kernel and the system
158 and service manager to control console log verbosity. For
159 details, see
160 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
161 </listitem>
162 </varlistentry>
163
164 <varlistentry>
165 <term><varname>debug</varname></term>
166 <listitem>
167 <para>Parameter understood by both the kernel and the system
168 and service manager to control console log verbosity. For
169 details, see
170 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
171 </listitem>
172 </varlistentry>
173
174 <varlistentry>
175 <term><varname>-b</varname></term>
dcd61450 176 <term><varname>rd.emergency</varname></term>
798d3a52 177 <term><varname>emergency</varname></term>
dcd61450 178 <term><varname>rd.rescue</varname></term>
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179 <term><varname>rescue</varname></term>
180 <term><varname>single</varname></term>
181 <term><varname>s</varname></term>
182 <term><varname>S</varname></term>
183 <term><varname>1</varname></term>
184 <term><varname>2</varname></term>
185 <term><varname>3</varname></term>
186 <term><varname>4</varname></term>
187 <term><varname>5</varname></term>
188 <listitem>
189 <para>Parameters understood by the system and service
dcd61450 190 manager, as compatibility and convenience options. For details, see
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191 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
192 </listitem>
193 </varlistentry>
194
195 <varlistentry>
196 <term><varname>locale.LANG=</varname></term>
197 <term><varname>locale.LANGUAGE=</varname></term>
198 <term><varname>locale.LC_CTYPE=</varname></term>
199 <term><varname>locale.LC_NUMERIC=</varname></term>
200 <term><varname>locale.LC_TIME=</varname></term>
201 <term><varname>locale.LC_COLLATE=</varname></term>
202 <term><varname>locale.LC_MONETARY=</varname></term>
203 <term><varname>locale.LC_MESSAGES=</varname></term>
204 <term><varname>locale.LC_PAPER=</varname></term>
205 <term><varname>locale.LC_NAME=</varname></term>
206 <term><varname>locale.LC_ADDRESS=</varname></term>
207 <term><varname>locale.LC_TELEPHONE=</varname></term>
208 <term><varname>locale.LC_MEASUREMENT=</varname></term>
209 <term><varname>locale.LC_IDENTIFICATION=</varname></term>
210 <listitem>
211 <para>Parameters understood by the system and service
212 manager to control locale and language settings. For
213 details, see
214 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
215 </listitem>
216 </varlistentry>
217
218 <varlistentry>
219 <term><varname>fsck.mode=</varname></term>
220 <term><varname>fsck.repair=</varname></term>
221
222 <listitem>
223 <para>Parameters understood by the file system checker
224 services. For details, see
225 <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
226 </listitem>
227 </varlistentry>
228
229 <varlistentry>
230 <term><varname>quotacheck.mode=</varname></term>
231
232 <listitem>
233 <para>Parameter understood by the file quota checker
234 service. For details, see
235 <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
236 </listitem>
237 </varlistentry>
238
239 <varlistentry>
240 <term><varname>systemd.journald.forward_to_syslog=</varname></term>
241 <term><varname>systemd.journald.forward_to_kmsg=</varname></term>
242 <term><varname>systemd.journald.forward_to_console=</varname></term>
243 <term><varname>systemd.journald.forward_to_wall=</varname></term>
244
245 <listitem>
246 <para>Parameters understood by the journal service. For
247 details, see
248 <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
249 </listitem>
250 </varlistentry>
251
252 <varlistentry>
253 <term><varname>vconsole.keymap=</varname></term>
72ccee50 254 <term><varname>vconsole.keymap_toggle=</varname></term>
798d3a52 255 <term><varname>vconsole.font=</varname></term>
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256 <term><varname>vconsole.font_map=</varname></term>
257 <term><varname>vconsole.font_unimap=</varname></term>
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258
259 <listitem>
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260 <para>Parameters understood by the virtual console setup logic. For details, see
261 <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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262 </listitem>
263 </varlistentry>
264
265 <varlistentry>
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266 <term><varname>udev.log_priority=</varname></term>
267 <term><varname>rd.udev.log_priority=</varname></term>
268 <term><varname>udev.children_max=</varname></term>
269 <term><varname>rd.udev.children_max=</varname></term>
270 <term><varname>udev.exec_delay=</varname></term>
271 <term><varname>rd.udev.exec_delay=</varname></term>
272 <term><varname>udev.event_timeout=</varname></term>
273 <term><varname>rd.udev.event_timeout=</varname></term>
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274 <term><varname>net.ifnames=</varname></term>
275
276 <listitem>
277 <para>Parameters understood by the device event managing
278 daemon. For details, see
279 <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
280 </listitem>
281 </varlistentry>
282
283 <varlistentry>
284 <term><varname>plymouth.enable=</varname></term>
285
286 <listitem>
287 <para>May be used to disable the Plymouth boot splash. For
288 details, see
289 <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
290 </listitem>
291 </varlistentry>
292
293 <varlistentry>
294 <term><varname>luks=</varname></term>
295 <term><varname>rd.luks=</varname></term>
296 <term><varname>luks.crypttab=</varname></term>
297 <term><varname>rd.luks.crypttab=</varname></term>
298 <term><varname>luks.name=</varname></term>
299 <term><varname>rd.luks.name=</varname></term>
300 <term><varname>luks.uuid=</varname></term>
301 <term><varname>rd.luks.uuid=</varname></term>
302 <term><varname>luks.options=</varname></term>
303 <term><varname>rd.luks.options=</varname></term>
304 <term><varname>luks.key=</varname></term>
305 <term><varname>rd.luks.key=</varname></term>
306
307 <listitem>
308 <para>Configures the LUKS full-disk encryption logic at
309 boot. For details, see
310 <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
311 </listitem>
312 </varlistentry>
313
314 <varlistentry>
315 <term><varname>fstab=</varname></term>
316 <term><varname>rd.fstab=</varname></term>
317
318 <listitem>
319 <para>Configures the <filename>/etc/fstab</filename> logic
320 at boot. For details, see
321 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
322 </listitem>
323 </varlistentry>
324
325 <varlistentry>
326 <term><varname>root=</varname></term>
327 <term><varname>rootfstype=</varname></term>
d6a12e7c 328 <term><varname>rootflags=</varname></term>
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329 <term><varname>ro</varname></term>
330 <term><varname>rw</varname></term>
331
332 <listitem>
333 <para>Configures the root file system and its file system
334 type and mount options, as well as whether it shall be
335 mounted read-only or read-writable initially. For details,
336 see
337 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
338 </listitem>
339 </varlistentry>
340
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341 <varlistentry>
342 <term><varname>mount.usr=</varname></term>
343 <term><varname>mount.usrfstype=</varname></term>
344 <term><varname>mount.usrflags=</varname></term>
345
346 <listitem>
347 <para>Configures the /usr file system (if required) and
348 its file system type and mount options. For details, see
349 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
350 </listitem>
351 </varlistentry>
352
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353 <varlistentry>
354 <term><varname>roothash=</varname></term>
355 <term><varname>systemd.verity=</varname></term>
356 <term><varname>rd.systemd.verity=</varname></term>
357 <term><varname>systemd.verity_root_data=</varname></term>
358 <term><varname>systemd.verity_root_hash=</varname></term>
359 <listitem>
360 <para>Configures the integrity protection root hash for the root file system, and other related
361 parameters. For details, see
362 <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
363 </listitem>
364 </varlistentry>
365
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366 <varlistentry>
367 <term><varname>systemd.gpt_auto=</varname></term>
368 <term><varname>rd.systemd.gpt_auto=</varname></term>
369
370 <listitem>
371 <para>Configures whether GPT based partition auto-discovery
372 shall be attempted. For details, see
373 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
374 </listitem>
375 </varlistentry>
376
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377 <varlistentry>
378 <term><varname>systemd.default_timeout_start_sec=</varname></term>
379
380 <listitem>
381 <para>Overwrites the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at boot. For details,
382 see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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383 </listitem>
384 </varlistentry>
385
386 <varlistentry>
387 <term><varname>systemd.watchdog_device=</varname></term>
388
389 <listitem>
390 <para>Overwrites the watchdog device path <varname>WatchdogDevice=</varname>. For details, see
391 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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392 </listitem>
393 </varlistentry>
394
798d3a52 395 <varlistentry>
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396 <term><varname>modules_load=</varname></term>
397 <term><varname>rd.modules_load=</varname></term>
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398
399 <listitem>
400 <para>Load a specific kernel module early at boot. For
401 details, see
402 <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
403 </listitem>
404 </varlistentry>
405
406 <varlistentry>
407 <term><varname>resume=</varname></term>
408
409 <listitem>
410 <para>Enables resume from hibernation using the specified
411 device. All
3ba3a79d 412 <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
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413 paths are supported. For details, see
414 <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
415 </listitem>
416 </varlistentry>
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417
418 <varlistentry>
419 <term><varname>systemd.firstboot=</varname></term>
420
421 <listitem><para>Takes a boolean argument, defaults to on. If off,
422 <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
423 will not query the user for basic system settings, even if the system boots up for the first time and the
424 relevant settings are not initialized yet.</para></listitem>
425 </varlistentry>
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426 </variablelist>
427
428 </refsect1>
429
430 <refsect1>
431 <title>See Also</title>
432 <para>
433 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
434 <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
af105d03 435 <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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436 <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
437 <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
438 <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
439 <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
440 <citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
441 <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
442 <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
443 <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
2f3dfc6f 444 <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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445 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
446 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
91214a37 447 <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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448 <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
449 <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
af105d03 450 <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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451 <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
452 <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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453 </para>
454 </refsect1>
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455
456</refentry>