man/kernel-command-line.xml

   1 <?xml version='1.0'?> <!--*-nxml-*-->
   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4
   5 <!--
   6   SPDX-License-Identifier: LGPL-2.1+
   7
   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
  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
  64     see
  65     <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink>
  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
  71     <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
  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>
  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>
  88         <term><varname>systemd.service_watchdogs</varname></term>
  89         <term><varname>systemd.show_status</varname></term>
  90         <term><varname>systemd.log_target=</varname></term>
  91         <term><varname>systemd.log_level=</varname></term>
  92         <term><varname>systemd.log_location=</varname></term>
  93         <term><varname>systemd.log_color</varname></term>
  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>
  97         <term><varname>systemd.machine_id=</varname></term>
  98         <term><varname>systemd.unified_cgroup_hierarchy</varname></term>
  99         <term><varname>systemd.legacy_systemd_cgroup_controller</varname></term>
 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>
 110         <term><varname>systemd.debug_shell</varname></term>
 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
 127           <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 128           </para>
 129         </listitem>
 130       </varlistentry>
 131
 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
 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>
 176         <term><varname>rd.emergency</varname></term>
 177         <term><varname>emergency</varname></term>
 178         <term><varname>rd.rescue</varname></term>
 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
 190           manager, as compatibility and convenience options. For details, see
 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>
 254         <term><varname>vconsole.keymap_toggle=</varname></term>
 255         <term><varname>vconsole.font=</varname></term>
 256         <term><varname>vconsole.font_map=</varname></term>
 257         <term><varname>vconsole.font_unimap=</varname></term>
 258
 259         <listitem>
 260           <para>Parameters understood by the virtual console setup logic. For details, see
 261           <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 262         </listitem>
 263       </varlistentry>
 264
 265       <varlistentry>
 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>
 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>
 328         <term><varname>rootflags=</varname></term>
 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
 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
 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
 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
 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>
 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>
 392         </listitem>
 393       </varlistentry>
 394
 395       <varlistentry>
 396         <term><varname>modules_load=</varname></term>
 397         <term><varname>rd.modules_load=</varname></term>
 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
 412           <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
 413           paths are supported. For details, see
 414           <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 415         </listitem>
 416       </varlistentry>
 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>
 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>,
 435         <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 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>,
 444         <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 445         <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 446         <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 447         <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 448         <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 449         <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 450         <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 451         <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 452         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 453       </para>
 454   </refsect1>
 455
 456 </refentry>