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c66e7bc7 1<?xml version='1.0'?> <!--*-nxml-*-->
3a54a157 2<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
12b42c76 3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
db9ecf05 4<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->
c66e7bc7 5
4623eecb 6<refentry id="kernel-command-line" xmlns:xi="http://www.w3.org/2001/XInclude">
c66e7bc7 7
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8 <refentryinfo>
9 <title>kernel-command-line</title>
10 <productname>systemd</productname>
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11 </refentryinfo>
12
13 <refmeta>
14 <refentrytitle>kernel-command-line</refentrytitle>
15 <manvolnum>7</manvolnum>
16 </refmeta>
17
18 <refnamediv>
19 <refname>kernel-command-line</refname>
20 <refpurpose>Kernel command line parameters</refpurpose>
21 </refnamediv>
22
23 <refsynopsisdiv>
24 <para><filename>/proc/cmdline</filename></para>
25 </refsynopsisdiv>
26
27 <refsect1>
28 <title>Description</title>
29
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30 <para>The kernel, the programs running in the initrd and in the host system may be configured at boot via
31 kernel command line arguments. In addition, various systemd tools look at the EFI variable
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32 <literal>SystemdOptions</literal> (if available). Both sources are combined, but the kernel command line
33 has higher priority. Please note that <emphasis>the EFI variable is only used by systemd tools, and is
34 ignored by the kernel and other user space tools</emphasis>, so it is not a replacement for the kernel
35 command line.</para>
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36
37 <para>For command line parameters understood by the kernel, please
ab1f7245 38 see
0e685823 39 <ulink url="https://docs.kernel.org/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink>
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40 and
41 <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
42
b66a6e1a 43 <para>For command line parameters understood by the initrd, see
af105d03 44 <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
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45 or the documentation of the specific initrd implementation of your
46 installation.</para>
47 </refsect1>
48
49 <refsect1>
50 <title>Core OS Command Line Arguments</title>
51
52 <variablelist class='kernel-commandline-options'>
53 <varlistentry>
54 <term><varname>systemd.unit=</varname></term>
55 <term><varname>rd.systemd.unit=</varname></term>
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56 <term><varname>systemd.dump_core</varname></term>
57 <term><varname>systemd.crash_chvt</varname></term>
58 <term><varname>systemd.crash_shell</varname></term>
59 <term><varname>systemd.crash_reboot</varname></term>
60 <term><varname>systemd.confirm_spawn</varname></term>
2a12e32e 61 <term><varname>systemd.service_watchdogs</varname></term>
770c4777 62 <term><varname>systemd.show_status</varname></term>
36cf4507 63 <term><varname>systemd.status_unit_format=</varname></term>
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64 <term><varname>systemd.log_target=</varname></term>
65 <term><varname>systemd.log_level=</varname></term>
798d3a52 66 <term><varname>systemd.log_location=</varname></term>
770c4777 67 <term><varname>systemd.log_color</varname></term>
8750a06b 68 <term><varname>systemd.log_ratelimit_kmsg</varname></term>
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69 <term><varname>systemd.default_standard_output=</varname></term>
70 <term><varname>systemd.default_standard_error=</varname></term>
71 <term><varname>systemd.setenv=</varname></term>
ee48dbd5 72 <term><varname>systemd.machine_id=</varname></term>
72267a55 73 <term><varname>systemd.set_credential=</varname></term>
de70ecb3 74 <term><varname>systemd.set_credential_binary=</varname></term>
72267a55 75 <term><varname>systemd.import_credentials=</varname></term>
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76 <term><varname>systemd.reload_limit_interval_sec=</varname></term>
77 <term><varname>systemd.reload_limit_burst=</varname></term>
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78 <listitem>
79 <para>Parameters understood by the system and service
80 manager to control system behavior. For details, see
81 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
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82
83 <xi:include href="version-info.xml" xpointer="v186"/>
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84 </listitem>
85 </varlistentry>
86
87 <varlistentry>
88 <term><varname>systemd.mask=</varname></term>
89 <term><varname>systemd.wants=</varname></term>
1d84ad94 90 <term><varname>systemd.debug_shell</varname></term>
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91 <listitem>
92 <para>Additional parameters understood by
93 <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
94 to mask or start specific units at boot, or invoke a debug
95 shell on tty9.</para>
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96
97 <xi:include href="version-info.xml" xpointer="v215"/>
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98 </listitem>
99 </varlistentry>
100
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101 <varlistentry>
102 <term><varname>systemd.run=</varname></term>
103 <term><varname>systemd.run_success_action=</varname></term>
104 <term><varname>systemd.run_failure_action=</varname></term>
105 <listitem>
106 <para>Additional parameters understood by
107 <citerefentry><refentrytitle>systemd-run-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, to
108 run a command line specified on the kernel command line as system service after booting up.</para>
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109
110 <xi:include href="version-info.xml" xpointer="v240"/>
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111 </listitem>
112 </varlistentry>
113
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114 <varlistentry>
115 <term><varname>systemd.early_core_pattern=</varname></term>
116 <listitem>
117 <para>During early boot, the generation of core dump files is disabled until a core dump handler (if any)
11fcfc53 118 takes over. This parameter allows specifying an absolute path where core dump files should be stored until
c6885f5f 119 a handler is installed. The path should be absolute and may contain specifiers, see
b7a47345 120 <citerefentry project='man-pages'><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details.</para>
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121
122 <xi:include href="version-info.xml" xpointer="v240"/>
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123 </listitem>
124 </varlistentry>
125
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126 <varlistentry>
127 <term><varname>systemd.restore_state=</varname></term>
128 <listitem>
129 <para>This parameter is understood by several system tools
130 to control whether or not they should restore system state
131 from the previous boot. For details, see
132 <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
133 and
af105d03 134 <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
798d3a52 135 </para>
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136
137 <xi:include href="version-info.xml" xpointer="v209"/>
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138 </listitem>
139 </varlistentry>
140
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141 <varlistentry>
142 <term><varname>systemd.volatile=</varname></term>
143 <listitem>
144 <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
145 the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root
3b121157 146 directory and <filename>/var/</filename> are mounted as specified on the kernel command line or
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147 <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
148 this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only
3b121157 149 <filename>/usr/</filename> is mounted from the file system configured as root device, in read-only mode. This
91214a37 150 enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
3b121157 151 configuration and no stored state in effect, as <filename>/etc/</filename> and <filename>/var/</filename> (as
91214a37 152 well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
13070a70 153 setting is set to <literal>state</literal> the root file system is mounted read-only, however
3b121157 154 <filename>/var/</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
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155 system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. If
156 this setting is set to <literal>overlay</literal> the root file system is set up as
157 <literal>overlayfs</literal> mount combining the read-only root directory with a writable
158 <literal>tmpfs</literal>, so that no modifications are made to disk, but the file system may be modified
159 nonetheless with all changes being lost at reboot. For details, see
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160 <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
161 and
162 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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163
164 <xi:include href="version-info.xml" xpointer="v233"/>
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165 </listitem>
166 </varlistentry>
167
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168 <varlistentry>
169 <term><varname>quiet</varname></term>
170 <listitem>
171 <para>Parameter understood by both the kernel and the system
172 and service manager to control console log verbosity. For
173 details, see
174 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
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175
176 <xi:include href="version-info.xml" xpointer="v186"/>
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177 </listitem>
178 </varlistentry>
179
180 <varlistentry>
181 <term><varname>debug</varname></term>
182 <listitem>
183 <para>Parameter understood by both the kernel and the system
184 and service manager to control console log verbosity. For
185 details, see
186 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
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187
188 <xi:include href="version-info.xml" xpointer="v205"/>
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189 </listitem>
190 </varlistentry>
191
192 <varlistentry>
193 <term><varname>-b</varname></term>
dcd61450 194 <term><varname>rd.emergency</varname></term>
798d3a52 195 <term><varname>emergency</varname></term>
dcd61450 196 <term><varname>rd.rescue</varname></term>
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197 <term><varname>rescue</varname></term>
198 <term><varname>single</varname></term>
199 <term><varname>s</varname></term>
200 <term><varname>S</varname></term>
201 <term><varname>1</varname></term>
202 <term><varname>2</varname></term>
203 <term><varname>3</varname></term>
204 <term><varname>4</varname></term>
205 <term><varname>5</varname></term>
206 <listitem>
207 <para>Parameters understood by the system and service
dcd61450 208 manager, as compatibility and convenience options. For details, see
798d3a52 209 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
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210
211 <xi:include href="version-info.xml" xpointer="v186"/>
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212 </listitem>
213 </varlistentry>
214
215 <varlistentry>
216 <term><varname>locale.LANG=</varname></term>
217 <term><varname>locale.LANGUAGE=</varname></term>
218 <term><varname>locale.LC_CTYPE=</varname></term>
219 <term><varname>locale.LC_NUMERIC=</varname></term>
220 <term><varname>locale.LC_TIME=</varname></term>
221 <term><varname>locale.LC_COLLATE=</varname></term>
222 <term><varname>locale.LC_MONETARY=</varname></term>
223 <term><varname>locale.LC_MESSAGES=</varname></term>
224 <term><varname>locale.LC_PAPER=</varname></term>
225 <term><varname>locale.LC_NAME=</varname></term>
226 <term><varname>locale.LC_ADDRESS=</varname></term>
227 <term><varname>locale.LC_TELEPHONE=</varname></term>
228 <term><varname>locale.LC_MEASUREMENT=</varname></term>
229 <term><varname>locale.LC_IDENTIFICATION=</varname></term>
230 <listitem>
231 <para>Parameters understood by the system and service
232 manager to control locale and language settings. For
233 details, see
234 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
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235
236 <xi:include href="version-info.xml" xpointer="v186"/>
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237 </listitem>
238 </varlistentry>
239
240 <varlistentry>
241 <term><varname>fsck.mode=</varname></term>
242 <term><varname>fsck.repair=</varname></term>
243
244 <listitem>
245 <para>Parameters understood by the file system checker
246 services. For details, see
247 <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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248
249 <xi:include href="version-info.xml" xpointer="v186"/>
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250 </listitem>
251 </varlistentry>
252
253 <varlistentry>
254 <term><varname>quotacheck.mode=</varname></term>
255
256 <listitem>
257 <para>Parameter understood by the file quota checker
258 service. For details, see
259 <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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260
261 <xi:include href="version-info.xml" xpointer="v186"/>
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262 </listitem>
263 </varlistentry>
264
265 <varlistentry>
266 <term><varname>systemd.journald.forward_to_syslog=</varname></term>
267 <term><varname>systemd.journald.forward_to_kmsg=</varname></term>
268 <term><varname>systemd.journald.forward_to_console=</varname></term>
269 <term><varname>systemd.journald.forward_to_wall=</varname></term>
270
271 <listitem>
272 <para>Parameters understood by the journal service. For
273 details, see
274 <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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275
276 <xi:include href="version-info.xml" xpointer="v186"/>
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277 </listitem>
278 </varlistentry>
279
280 <varlistentry>
281 <term><varname>vconsole.keymap=</varname></term>
72ccee50 282 <term><varname>vconsole.keymap_toggle=</varname></term>
798d3a52 283 <term><varname>vconsole.font=</varname></term>
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284 <term><varname>vconsole.font_map=</varname></term>
285 <term><varname>vconsole.font_unimap=</varname></term>
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286
287 <listitem>
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288 <para>Parameters understood by the virtual console setup logic. For details, see
289 <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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290
291 <xi:include href="version-info.xml" xpointer="v186"/>
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292 </listitem>
293 </varlistentry>
294
295 <varlistentry>
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296 <term><varname>udev.log_level=</varname></term>
297 <term><varname>rd.udev.log_level=</varname></term>
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298 <term><varname>udev.children_max=</varname></term>
299 <term><varname>rd.udev.children_max=</varname></term>
300 <term><varname>udev.exec_delay=</varname></term>
301 <term><varname>rd.udev.exec_delay=</varname></term>
302 <term><varname>udev.event_timeout=</varname></term>
303 <term><varname>rd.udev.event_timeout=</varname></term>
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304 <term><varname>udev.timeout_signal=</varname></term>
305 <term><varname>rd.udev.timeout_signal=</varname></term>
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306 <term><varname>udev.blockdev_read_only</varname></term>
307 <term><varname>rd.udev.blockdev_read_only</varname></term>
798d3a52 308 <term><varname>net.ifnames=</varname></term>
f7e81fd9 309 <term><varname>net.naming-scheme=</varname></term>
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310
311 <listitem>
312 <para>Parameters understood by the device event managing
313 daemon. For details, see
314 <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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315
316 <xi:include href="version-info.xml" xpointer="v186"/>
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317 </listitem>
318 </varlistentry>
319
320 <varlistentry>
321 <term><varname>plymouth.enable=</varname></term>
322
323 <listitem>
324 <para>May be used to disable the Plymouth boot splash. For
325 details, see
326 <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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327
328 <xi:include href="version-info.xml" xpointer="v186"/>
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329 </listitem>
330 </varlistentry>
331
332 <varlistentry>
333 <term><varname>luks=</varname></term>
334 <term><varname>rd.luks=</varname></term>
335 <term><varname>luks.crypttab=</varname></term>
336 <term><varname>rd.luks.crypttab=</varname></term>
337 <term><varname>luks.name=</varname></term>
338 <term><varname>rd.luks.name=</varname></term>
339 <term><varname>luks.uuid=</varname></term>
340 <term><varname>rd.luks.uuid=</varname></term>
341 <term><varname>luks.options=</varname></term>
342 <term><varname>rd.luks.options=</varname></term>
343 <term><varname>luks.key=</varname></term>
344 <term><varname>rd.luks.key=</varname></term>
345
346 <listitem>
347 <para>Configures the LUKS full-disk encryption logic at
348 boot. For details, see
349 <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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350
351 <xi:include href="version-info.xml" xpointer="v186"/>
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352 </listitem>
353 </varlistentry>
354
355 <varlistentry>
356 <term><varname>fstab=</varname></term>
357 <term><varname>rd.fstab=</varname></term>
358
359 <listitem>
360 <para>Configures the <filename>/etc/fstab</filename> logic
361 at boot. For details, see
362 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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363
364 <xi:include href="version-info.xml" xpointer="v186"/>
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365 </listitem>
366 </varlistentry>
367
368 <varlistentry>
369 <term><varname>root=</varname></term>
370 <term><varname>rootfstype=</varname></term>
d6a12e7c 371 <term><varname>rootflags=</varname></term>
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372 <term><varname>ro</varname></term>
373 <term><varname>rw</varname></term>
374
375 <listitem>
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376 <para>Configures the root file system and its file system type and mount options, as well as
377 whether it shall be mounted read-only or read-write initially. For details, see
798d3a52 378 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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379
380 <para>If <varname>root=</varname> is not set (or set to <literal>gpt-auto</literal>) the automatic
381 root partition discovery implemented by
382 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
383 will be in effect. In this case <varname>rootfstype=</varname>, <varname>rootflags=</varname>,
384 <varname>ro</varname>, <varname>rw</varname> will be interpreted by
385 <command>systemd-gpt-auto-generator</command>.</para>
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386
387 <xi:include href="version-info.xml" xpointer="v215"/>
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388 </listitem>
389 </varlistentry>
390
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391 <varlistentry>
392 <term><varname>mount.usr=</varname></term>
393 <term><varname>mount.usrfstype=</varname></term>
394 <term><varname>mount.usrflags=</varname></term>
395
396 <listitem>
397 <para>Configures the /usr file system (if required) and
398 its file system type and mount options. For details, see
399 <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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400
401 <xi:include href="version-info.xml" xpointer="v235"/>
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402 </listitem>
403 </varlistentry>
404
2f3dfc6f 405 <varlistentry>
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406 <term><varname>veritytab=</varname></term>
407 <term><varname>rd.veritytab=</varname></term>
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408 <term><varname>roothash=</varname></term>
409 <term><varname>systemd.verity=</varname></term>
410 <term><varname>rd.systemd.verity=</varname></term>
411 <term><varname>systemd.verity_root_data=</varname></term>
412 <term><varname>systemd.verity_root_hash=</varname></term>
0141102f 413 <term><varname>systemd.verity.root_options=</varname></term>
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414 <term><varname>usrhash=</varname></term>
415 <term><varname>systemd.verity_usr_data=</varname></term>
416 <term><varname>systemd.verity_usr_hash=</varname></term>
417 <term><varname>systemd.verity_usr_options=</varname></term>
2f3dfc6f 418 <listitem>
e5196eee 419 <para>Configures the integrity protection root hash for the root and <filename>/usr</filename> file systems, and other related
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420 parameters. For details, see
421 <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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422
423 <xi:include href="version-info.xml" xpointer="v233"/>
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424 </listitem>
425 </varlistentry>
426
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427 <varlistentry>
428 <term><varname>systemd.getty_auto=</varname></term>
429
430 <listitem>
431 <para>Configures whether the <filename>serial-getty@.service</filename> will run.
432 For details, see
433 <citerefentry><refentrytitle>systemd-getty-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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434
435 <xi:include href="version-info.xml" xpointer="v250"/>
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436 </listitem>
437 </varlistentry>
438
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439 <varlistentry>
440 <term><varname>systemd.gpt_auto=</varname></term>
441 <term><varname>rd.systemd.gpt_auto=</varname></term>
442
443 <listitem>
9ea81191 444 <para>Configures whether GPT-based partition auto-discovery shall be attempted. For details, see
798d3a52 445 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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446
447 <xi:include href="version-info.xml" xpointer="v215"/>
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448 </listitem>
449 </varlistentry>
450
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451 <varlistentry>
452 <term><varname>systemd.image_policy=</varname></term>
453 <term><varname>rd.systemd.image_policy=</varname></term>
454
455 <listitem><para>When GPT-based partition auto-discovery is used, configures the image dissection
456 policy string to apply, as per
457 <citerefentry><refentrytitle>systemd.image-policy</refentrytitle><manvolnum>7</manvolnum></citerefentry>. For
458 details see
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459 <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
460
461 <xi:include href="version-info.xml" xpointer="v254"/></listitem>
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462 </varlistentry>
463
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464 <varlistentry>
465 <term><varname>systemd.default_timeout_start_sec=</varname></term>
466
467 <listitem>
ba669952 468 <para>Overrides the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at
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469 boot. For details, see
470 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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471
472 <xi:include href="version-info.xml" xpointer="v230"/>
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473 </listitem>
474 </varlistentry>
475
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476 <varlistentry>
477 <term><varname>systemd.default_device_timeout_sec=</varname></term>
478
479 <listitem>
480 <para>Overrides the default device timeout <varname>DefaultDeviceTimeoutSec=</varname> at boot. For
481 details, see
482 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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483
484 <xi:include href="version-info.xml" xpointer="v254"/>
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485 </listitem>
486 </varlistentry>
487
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488 <varlistentry>
489 <term><varname>systemd.watchdog_device=</varname></term>
490
491 <listitem>
ba669952 492 <para>Overrides the watchdog device path <varname>WatchdogDevice=</varname>. For details, see
9c5ea4b1 493 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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494
495 <xi:include href="version-info.xml" xpointer="v236"/>
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496 </listitem>
497 </varlistentry>
498
499 <varlistentry>
500 <term><varname>systemd.watchdog_sec=</varname></term>
501
502 <listitem>
ba669952 503 <para>Overrides the watchdog timeout settings otherwise configured with
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504 <varname>RuntimeWatchdog=</varname>, <varname>RebootWatchdog=</varname> and
505 <varname>KExecWatchdogSec=</varname>. Takes a time value (if no unit is specified, seconds is the
506 implicitly assumed time unit) or the special strings <literal>off</literal> or
507 <literal>default</literal>. For details, see
c75396c3 508 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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509
510 <xi:include href="version-info.xml" xpointer="v250"/>
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511 </listitem>
512 </varlistentry>
513
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514 <varlistentry>
515 <term><varname>systemd.watchdog_pre_sec=</varname></term>
516
517 <listitem>
518 <para>Overrides the watchdog pre-timeout settings otherwise configured with
519 <varname>RuntimeWatchdogPreSec=</varname>. Takes a time value (if no unit is specified, seconds is the
520 implicitly assumed time unit) or the special strings <literal>off</literal> or
521 <literal>default</literal>. For details, see
522 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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523
524 <xi:include href="version-info.xml" xpointer="v251"/>
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525 </listitem>
526 </varlistentry>
527
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528 <varlistentry>
529 <term><varname>systemd.watchdog_pretimeout_governor=</varname></term>
530
531 <listitem>
532 <para>Overrides the watchdog pre-timeout settings otherwise configured with
533 <varname>RuntimeWatchdogPreGovernor=</varname>. Takes a string value. For details, see
534 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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535
536 <xi:include href="version-info.xml" xpointer="v251"/>
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537 </listitem>
538 </varlistentry>
539
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540 <varlistentry>
541 <term><varname>systemd.cpu_affinity=</varname></term>
542
543 <listitem>
544 <para>Overrides the CPU affinity mask for the service manager and the default for all child
545 processes it forks. This takes precedence over <varname>CPUAffinity=</varname>, see
546 <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
547 for details.</para>
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548
549 <xi:include href="version-info.xml" xpointer="v245"/>
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550 </listitem>
551 </varlistentry>
552
798d3a52 553 <varlistentry>
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554 <term><varname>modules_load=</varname></term>
555 <term><varname>rd.modules_load=</varname></term>
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556
557 <listitem>
558 <para>Load a specific kernel module early at boot. For
559 details, see
560 <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
ec07c3c8 561
aefdc112 562 <xi:include href="version-info.xml" xpointer="v187"/>
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563 </listitem>
564 </varlistentry>
565
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566 <varlistentry>
567 <term><varname>nameserver=</varname></term>
568 <term><varname>domain=</varname></term>
569
570 <listitem><para>Configures DNS server information and search domains, see
571 <citerefentry><refentrytitle>systemd-resolved.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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572 for details.</para>
573
574 <xi:include href="version-info.xml" xpointer="v253"/></listitem>
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575 </varlistentry>
576
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577 <varlistentry>
578 <term><varname>resume=</varname></term>
8b6805a2 579 <term><varname>resumeflags=</varname></term>
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580
581 <listitem>
582 <para>Enables resume from hibernation using the specified
8b6805a2 583 device and mount options. All
3ba3a79d 584 <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
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585 paths are supported. For details, see
586 <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
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587
588 <xi:include href="version-info.xml" xpointer="v217"/>
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589 </listitem>
590 </varlistentry>
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591
592 <varlistentry>
593 <term><varname>systemd.firstboot=</varname></term>
594
595 <listitem><para>Takes a boolean argument, defaults to on. If off,
596 <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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597 and
598 <citerefentry><refentrytitle>systemd-homed-firstboot.service</refentrytitle><manvolnum>1</manvolnum></citerefentry>
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599 will not query the user for basic system settings, even if the system boots up for the first time and
600 the relevant settings are not initialized yet. Not to be confused with
601 <varname>systemd.condition-first-boot=</varname> (see below), which overrides the result of the
602 <varname>ConditionFirstBoot=</varname> unit file condition, and thus controls more than just
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603 <filename>systemd-firstboot.service</filename> behaviour.</para>
604
605 <xi:include href="version-info.xml" xpointer="v233"/></listitem>
f582cbca 606 </varlistentry>
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607
608 <varlistentry>
609 <term><varname>systemd.condition-needs-update=</varname></term>
610
611 <listitem><para>Takes a boolean argument. If specified, overrides the result of
612 <varname>ConditionNeedsUpdate=</varname> unit condition checks. See
613 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
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614 details.</para>
615
616 <xi:include href="version-info.xml" xpointer="v246"/></listitem>
f8b4ae29 617 </varlistentry>
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618
619 <varlistentry>
620 <term><varname>systemd.condition-first-boot=</varname></term>
621
622 <listitem><para>Takes a boolean argument. If specified, overrides the result of
623 <varname>ConditionFirstBoot=</varname> unit condition checks. See
624 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> for
625 details. Not to be confused with <varname>systemd.firstboot=</varname> which only controls behaviour
626 of the <filename>systemd-firstboot.service</filename> system service but has no effect on the
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627 condition check (see above).</para>
628
629 <xi:include href="version-info.xml" xpointer="v246"/></listitem>
814872e9 630 </varlistentry>
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631
632 <varlistentry>
633 <term><varname>systemd.clock-usec=</varname></term>
634
e503019b 635 <listitem><para>Takes a decimal, numeric timestamp in μs since January 1st 1970, 00:00am, to set the
18d9cee0 636 system clock to. The system time is set to the specified timestamp early during boot. It is not
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637 propagated to the hardware clock (RTC).</para>
638
639 <xi:include href="version-info.xml" xpointer="v246"/></listitem>
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640 </varlistentry>
641
642 <varlistentry>
643 <term><varname>systemd.random-seed=</varname></term>
644
645 <listitem><para>Takes a base64 encoded random seed value to credit with full entropy to the kernel's
646 random pool during early service manager initialization. This option is useful in testing
647 environments where delays due to random pool initialization in entropy starved virtual machines shall
648 be avoided.</para>
649
650 <para>Note that if this option is used the seed is accessible to unprivileged programs from
651 <filename>/proc/cmdline</filename>. This option is hence a security risk when used outside of test
652 systems, since the (possibly) only seed used for initialization of the kernel's entropy pool might be
653 easily acquired by unprivileged programs.</para>
654
655 <para>It is recommended to pass 512 bytes of randomized data (as that matches the Linux kernel pool
656 size), which may be generated with a command like the following:</para>
657
658 <programlisting>dd if=/dev/urandom bs=512 count=1 status=none | base64 -w 0</programlisting>
659
660 <para>Again: do not use this option outside of testing environments, it's a security risk elsewhere,
661 as secret key material derived from the entropy pool can possibly be reconstructed by unprivileged
662 programs.</para>
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663
664 <xi:include href="version-info.xml" xpointer="v246"/>
18d9cee0 665 </listitem>
3753325b 666 </varlistentry>
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667
668 <varlistentry>
669 <term><varname>systemd.hostname=</varname></term>
670
671 <listitem><para>Accepts a hostname to set during early boot. If specified takes precedence over what
672 is set in <filename>/etc/hostname</filename>. Note that this does not bar later runtime changes to
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673 the hostname, it simply controls the initial hostname set during early boot.</para>
674
675 <xi:include href="version-info.xml" xpointer="v246"/></listitem>
34293dfa 676 </varlistentry>
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677
678 <varlistentry>
679 <term><varname>systemd.tty.term.<replaceable>tty</replaceable>=</varname></term>
680 <term><varname>systemd.tty.rows.<replaceable>tty</replaceable>=</varname></term>
681 <term><varname>systemd.tty.columns.<replaceable>tty</replaceable>=</varname></term>
682
683 <listitem><para>These arguments allow configuring default values for <varname>$TERM</varname>,
684 <varname>TTYRows=</varname>, and <varname>TTYColumns=</varname> for tty
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685 <replaceable>tty</replaceable>. Additionally, <varname>systemd.tty.term.console</varname> will
686 configure the <varname>$TERM</varname> value used by <command>systemd</command> if not set explicitly
687 using <varname>TERM</varname> on the kernel command line. The tty name should be specified without
688 the <filename>/dev/</filename> prefix (e.g. <literal>systemd.tty.rows.ttyS0=80</literal>).
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689 </para>
690
691 <xi:include href="version-info.xml" xpointer="v254"/></listitem>
4d62ee55 692 </varlistentry>
798d3a52 693 </variablelist>
7a9e0bd0 694 </refsect1>
798d3a52 695
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696 <refsect1>
697 <title>History</title>
698
699 <variablelist>
700 <varlistentry>
701 <term>systemd 252</term>
702 <listitem><para>Kernel command-line arguments <varname>systemd.unified_cgroup_hierarchy</varname>
703 and <varname>systemd.legacy_systemd_cgroup_controller</varname> were deprecated. Please switch to
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704 the unified cgroup hierarchy.</para>
705
706 <xi:include href="version-info.xml" xpointer="v252"/></listitem>
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707 </varlistentry>
708 </variablelist>
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709 </refsect1>
710
711 <refsect1>
712 <title>See Also</title>
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713 <para><simplelist type="inline">
714 <member><citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
715 <member><citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry></member>
716 <member><citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
717 <member><citerefentry><refentrytitle>systemd.system-credentials</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
718 <member><citerefentry><refentrytitle>smbios-type-11</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
719 <member><citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry></member>
720 <member><citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
721 <member><citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
722 <member><citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
723 <member><citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
724 <member><citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
725 <member><citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
726 <member><citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
727 <member><citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
728 <member><citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
729 <member><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
730 <member><citerefentry><refentrytitle>systemd-getty-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
731 <member><citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
732 <member><citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
733 <member><citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
734 <member><citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
735 <member><citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
736 <member><citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
737 <member><citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry></member>
738 <member><citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry></member>
739 </simplelist></para>
798d3a52 740 </refsect1>
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741
742</refentry>