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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.
14
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
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62 see
63 <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink>
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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>mount.usr=</varname></term>
340 <term><varname>mount.usrfstype=</varname></term>
341 <term><varname>mount.usrflags=</varname></term>
342
343 <listitem>
344 <para>Configures the /usr file system (if required) and
345 its file system type and mount options. For details, see
346 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
347 </listitem>
348 </varlistentry>
349
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350 <varlistentry>
351 <term><varname>roothash=</varname></term>
352 <term><varname>systemd.verity=</varname></term>
353 <term><varname>rd.systemd.verity=</varname></term>
354 <term><varname>systemd.verity_root_data=</varname></term>
355 <term><varname>systemd.verity_root_hash=</varname></term>
356 <listitem>
357 <para>Configures the integrity protection root hash for the root file system, and other related
358 parameters. For details, see
359 <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
360 </listitem>
361 </varlistentry>
362
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363 <varlistentry>
364 <term><varname>systemd.gpt_auto=</varname></term>
365 <term><varname>rd.systemd.gpt_auto=</varname></term>
366
367 <listitem>
368 <para>Configures whether GPT based partition auto-discovery
369 shall be attempted. For details, see
370 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
371 </listitem>
372 </varlistentry>
373
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374 <varlistentry>
375 <term><varname>systemd.default_timeout_start_sec=</varname></term>
376
377 <listitem>
378 <para>Overwrites the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at boot. For details,
379 see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
380 </listitem>
381 </varlistentry>
382
798d3a52 383 <varlistentry>
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384 <term><varname>modules_load=</varname></term>
385 <term><varname>rd.modules_load=</varname></term>
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386
387 <listitem>
388 <para>Load a specific kernel module early at boot. For
389 details, see
390 <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
391 </listitem>
392 </varlistentry>
393
394 <varlistentry>
395 <term><varname>resume=</varname></term>
396
397 <listitem>
398 <para>Enables resume from hibernation using the specified
399 device. All
3ba3a79d 400 <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
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401 paths are supported. For details, see
402 <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
403 </listitem>
404 </varlistentry>
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405
406 <varlistentry>
407 <term><varname>systemd.firstboot=</varname></term>
408
409 <listitem><para>Takes a boolean argument, defaults to on. If off,
410 <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
411 will not query the user for basic system settings, even if the system boots up for the first time and the
412 relevant settings are not initialized yet.</para></listitem>
413 </varlistentry>
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414 </variablelist>
415
416 </refsect1>
417
418 <refsect1>
419 <title>See Also</title>
420 <para>
421 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
422 <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
af105d03 423 <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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424 <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
425 <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
426 <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
427 <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
428 <citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
429 <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
430 <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
431 <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
2f3dfc6f 432 <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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433 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
434 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
91214a37 435 <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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436 <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
437 <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
af105d03 438 <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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439 <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
440 <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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441 </para>
442 </refsect1>
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443
444</refentry>