man/kernel-command-line.xml

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   5
   6 <refentry id="kernel-command-line">
   7
   8   <refentryinfo>
   9     <title>kernel-command-line</title>
  10     <productname>systemd</productname>
  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
  30     <para>The kernel, the initial RAM disk (initrd) and
  31     basic userspace functionality may be configured at boot via
  32     kernel command line arguments.</para>
  33
  34     <para>For command line parameters understood by the kernel, please
  35     see
  36     <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink>
  37     and
  38     <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
  39
  40     <para>For command line parameters understood by the initial RAM
  41     disk, please see
  42     <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
  43     or the documentation of the specific initrd implementation of your
  44     installation.</para>
  45   </refsect1>
  46
  47   <refsect1>
  48     <title>Core OS Command Line Arguments</title>
  49
  50     <variablelist class='kernel-commandline-options'>
  51       <varlistentry>
  52         <term><varname>systemd.unit=</varname></term>
  53         <term><varname>rd.systemd.unit=</varname></term>
  54         <term><varname>systemd.dump_core</varname></term>
  55         <term><varname>systemd.early_core_pattern=</varname></term>
  56         <term><varname>systemd.crash_chvt</varname></term>
  57         <term><varname>systemd.crash_shell</varname></term>
  58         <term><varname>systemd.crash_reboot</varname></term>
  59         <term><varname>systemd.confirm_spawn</varname></term>
  60         <term><varname>systemd.service_watchdogs</varname></term>
  61         <term><varname>systemd.show_status</varname></term>
  62         <term><varname>systemd.status_unit_format=</varname></term>
  63         <term><varname>systemd.log_target=</varname></term>
  64         <term><varname>systemd.log_level=</varname></term>
  65         <term><varname>systemd.log_location=</varname></term>
  66         <term><varname>systemd.log_color</varname></term>
  67         <term><varname>systemd.default_standard_output=</varname></term>
  68         <term><varname>systemd.default_standard_error=</varname></term>
  69         <term><varname>systemd.setenv=</varname></term>
  70         <term><varname>systemd.machine_id=</varname></term>
  71         <term><varname>systemd.unified_cgroup_hierarchy</varname></term>
  72         <term><varname>systemd.legacy_systemd_cgroup_controller</varname></term>
  73         <listitem>
  74           <para>Parameters understood by the system and service
  75           manager to control system behavior. For details, see
  76           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
  77         </listitem>
  78       </varlistentry>
  79
  80       <varlistentry>
  81         <term><varname>systemd.mask=</varname></term>
  82         <term><varname>systemd.wants=</varname></term>
  83         <term><varname>systemd.debug_shell</varname></term>
  84         <listitem>
  85           <para>Additional parameters understood by
  86           <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  87           to mask or start specific units at boot, or invoke a debug
  88           shell on tty9.</para>
  89         </listitem>
  90       </varlistentry>
  91
  92       <varlistentry>
  93         <term><varname>systemd.run=</varname></term>
  94         <term><varname>systemd.run_success_action=</varname></term>
  95         <term><varname>systemd.run_failure_action=</varname></term>
  96         <listitem>
  97           <para>Additional parameters understood by
  98           <citerefentry><refentrytitle>systemd-run-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, to
  99           run a command line specified on the kernel command line as system service after booting up.</para>
 100         </listitem>
 101       </varlistentry>
 102
 103       <varlistentry>
 104         <term><varname>systemd.early_core_pattern=</varname></term>
 105         <listitem>
 106           <para>During early boot, the generation of core dump files is disabled until a core dump handler (if any)
 107           takes over. This parameter allows to specifies an absolute path where core dump files should be stored until
 108           a handler is installed. The path should be absolute and may contain specifiers, see
 109           <citerefentry><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details.</para>
 110         </listitem>
 111       </varlistentry>
 112
 113       <varlistentry>
 114         <term><varname>systemd.restore_state=</varname></term>
 115         <listitem>
 116           <para>This parameter is understood by several system tools
 117           to control whether or not they should restore system state
 118           from the previous boot. For details, see
 119           <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 120           and
 121           <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 122           </para>
 123         </listitem>
 124       </varlistentry>
 125
 126       <varlistentry>
 127         <term><varname>systemd.volatile=</varname></term>
 128         <listitem>
 129           <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
 130           the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root
 131           directory and <filename>/var</filename> are mounted as specified on the kernel command line or
 132           <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
 133           this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only
 134           <filename>/usr</filename> is mounted from the file system configured as root device, in read-only mode. This
 135           enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
 136           configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as
 137           well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
 138           setting is set to <literal>state</literal> the root file system is mounted read-only, however
 139           <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
 140           system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. If
 141           this setting is set to <literal>overlay</literal> the root file system is set up as
 142           <literal>overlayfs</literal> mount combining the read-only root directory with a writable
 143           <literal>tmpfs</literal>, so that no modifications are made to disk, but the file system may be modified
 144           nonetheless with all changes being lost at reboot. For details, 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
 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>
 173         <term><varname>rd.emergency</varname></term>
 174         <term><varname>emergency</varname></term>
 175         <term><varname>rd.rescue</varname></term>
 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
 187           manager, as compatibility and convenience options. For details, see
 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>
 251         <term><varname>vconsole.keymap_toggle=</varname></term>
 252         <term><varname>vconsole.font=</varname></term>
 253         <term><varname>vconsole.font_map=</varname></term>
 254         <term><varname>vconsole.font_unimap=</varname></term>
 255
 256         <listitem>
 257           <para>Parameters understood by the virtual console setup logic. For details, see
 258           <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 259         </listitem>
 260       </varlistentry>
 261
 262       <varlistentry>
 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>
 271         <term><varname>net.ifnames=</varname></term>
 272         <term><varname>net.naming-scheme=</varname></term>
 273
 274         <listitem>
 275           <para>Parameters understood by the device event managing
 276           daemon. For details, see
 277           <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 278         </listitem>
 279       </varlistentry>
 280
 281       <varlistentry>
 282         <term><varname>plymouth.enable=</varname></term>
 283
 284         <listitem>
 285           <para>May be used to disable the Plymouth boot splash. For
 286           details, see
 287           <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 288         </listitem>
 289       </varlistentry>
 290
 291       <varlistentry>
 292         <term><varname>luks=</varname></term>
 293         <term><varname>rd.luks=</varname></term>
 294         <term><varname>luks.crypttab=</varname></term>
 295         <term><varname>rd.luks.crypttab=</varname></term>
 296         <term><varname>luks.name=</varname></term>
 297         <term><varname>rd.luks.name=</varname></term>
 298         <term><varname>luks.uuid=</varname></term>
 299         <term><varname>rd.luks.uuid=</varname></term>
 300         <term><varname>luks.options=</varname></term>
 301         <term><varname>rd.luks.options=</varname></term>
 302         <term><varname>luks.key=</varname></term>
 303         <term><varname>rd.luks.key=</varname></term>
 304
 305         <listitem>
 306           <para>Configures the LUKS full-disk encryption logic at
 307           boot. For details, see
 308           <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 309         </listitem>
 310       </varlistentry>
 311
 312       <varlistentry>
 313         <term><varname>fstab=</varname></term>
 314         <term><varname>rd.fstab=</varname></term>
 315
 316         <listitem>
 317           <para>Configures the <filename>/etc/fstab</filename> logic
 318           at boot. For details, see
 319           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 320         </listitem>
 321       </varlistentry>
 322
 323       <varlistentry>
 324         <term><varname>root=</varname></term>
 325         <term><varname>rootfstype=</varname></term>
 326         <term><varname>rootflags=</varname></term>
 327         <term><varname>ro</varname></term>
 328         <term><varname>rw</varname></term>
 329
 330         <listitem>
 331           <para>Configures the root file system and its file system
 332           type and mount options, as well as whether it shall be
 333           mounted read-only or read-write initially. For details,
 334           see
 335           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 336         </listitem>
 337       </varlistentry>
 338
 339       <varlistentry>
 340         <term><varname>mount.usr=</varname></term>
 341         <term><varname>mount.usrfstype=</varname></term>
 342         <term><varname>mount.usrflags=</varname></term>
 343
 344         <listitem>
 345           <para>Configures the /usr file system (if required) and
 346           its file system type and mount options. For details, see
 347           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 348         </listitem>
 349       </varlistentry>
 350
 351       <varlistentry>
 352         <term><varname>roothash=</varname></term>
 353         <term><varname>systemd.verity=</varname></term>
 354         <term><varname>rd.systemd.verity=</varname></term>
 355         <term><varname>systemd.verity_root_data=</varname></term>
 356         <term><varname>systemd.verity_root_hash=</varname></term>
 357         <listitem>
 358           <para>Configures the integrity protection root hash for the root file system, and other related
 359           parameters. For details, see
 360           <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 361         </listitem>
 362       </varlistentry>
 363
 364       <varlistentry>
 365         <term><varname>systemd.gpt_auto=</varname></term>
 366         <term><varname>rd.systemd.gpt_auto=</varname></term>
 367
 368         <listitem>
 369           <para>Configures whether GPT based partition auto-discovery
 370           shall be attempted. For details, see
 371           <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 372         </listitem>
 373       </varlistentry>
 374
 375       <varlistentry>
 376         <term><varname>systemd.default_timeout_start_sec=</varname></term>
 377
 378         <listitem>
 379           <para>Overwrites the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at boot. For details,
 380           see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 381         </listitem>
 382       </varlistentry>
 383
 384       <varlistentry>
 385         <term><varname>systemd.watchdog_device=</varname></term>
 386
 387         <listitem>
 388           <para>Overwrites the watchdog device path <varname>WatchdogDevice=</varname>. For details, see
 389           <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 390         </listitem>
 391       </varlistentry>
 392
 393       <varlistentry>
 394         <term><varname>modules_load=</varname></term>
 395         <term><varname>rd.modules_load=</varname></term>
 396
 397         <listitem>
 398           <para>Load a specific kernel module early at boot. For
 399           details, see
 400           <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 401         </listitem>
 402       </varlistentry>
 403
 404       <varlistentry>
 405         <term><varname>resume=</varname></term>
 406         <term><varname>resumeflags=</varname></term>
 407
 408         <listitem>
 409           <para>Enables resume from hibernation using the specified
 410           device and mount options. All
 411           <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
 412           paths are supported. For details, see
 413           <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 414         </listitem>
 415       </varlistentry>
 416
 417       <varlistentry>
 418         <term><varname>systemd.firstboot=</varname></term>
 419
 420         <listitem><para>Takes a boolean argument, defaults to on. If off,
 421         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 422         will not query the user for basic system settings, even if the system boots up for the first time and the
 423         relevant settings are not initialized yet.</para></listitem>
 424       </varlistentry>
 425     </variablelist>
 426
 427   </refsect1>
 428
 429   <refsect1>
 430       <title>See Also</title>
 431       <para>
 432         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 433         <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</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>