man/kernel-command-line.xml

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