man/kernel-command-line.xml

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