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   </refentryinfo>
  15
  16   <refmeta>
  17     <refentrytitle>kernel-command-line</refentrytitle>
  18     <manvolnum>7</manvolnum>
  19   </refmeta>
  20
  21   <refnamediv>
  22     <refname>kernel-command-line</refname>
  23     <refpurpose>Kernel command line parameters</refpurpose>
  24   </refnamediv>
  25
  26   <refsynopsisdiv>
  27     <para><filename>/proc/cmdline</filename></para>
  28   </refsynopsisdiv>
  29
  30   <refsect1>
  31     <title>Description</title>
  32
  33     <para>The kernel, the initial RAM disk (initrd) and
  34     basic userspace functionality may be configured at boot via
  35     kernel command line arguments.</para>
  36
  37     <para>For command line parameters understood by the kernel, please
  38     see
  39     <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink>
  40     and
  41     <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
  42
  43     <para>For command line parameters understood by the initial RAM
  44     disk, please see
  45     <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
  46     or the documentation of the specific initrd implementation of your
  47     installation.</para>
  48   </refsect1>
  49
  50   <refsect1>
  51     <title>Core OS Command Line Arguments</title>
  52
  53     <variablelist class='kernel-commandline-options'>
  54       <varlistentry>
  55         <term><varname>systemd.unit=</varname></term>
  56         <term><varname>rd.systemd.unit=</varname></term>
  57         <term><varname>systemd.dump_core</varname></term>
  58         <term><varname>systemd.early_core_pattern=</varname></term>
  59         <term><varname>systemd.crash_chvt</varname></term>
  60         <term><varname>systemd.crash_shell</varname></term>
  61         <term><varname>systemd.crash_reboot</varname></term>
  62         <term><varname>systemd.confirm_spawn</varname></term>
  63         <term><varname>systemd.service_watchdogs</varname></term>
  64         <term><varname>systemd.show_status</varname></term>
  65         <term><varname>systemd.log_target=</varname></term>
  66         <term><varname>systemd.log_level=</varname></term>
  67         <term><varname>systemd.log_location=</varname></term>
  68         <term><varname>systemd.log_color</varname></term>
  69         <term><varname>systemd.default_standard_output=</varname></term>
  70         <term><varname>systemd.default_standard_error=</varname></term>
  71         <term><varname>systemd.setenv=</varname></term>
  72         <term><varname>systemd.machine_id=</varname></term>
  73         <term><varname>systemd.unified_cgroup_hierarchy</varname></term>
  74         <term><varname>systemd.legacy_systemd_cgroup_controller</varname></term>
  75         <listitem>
  76           <para>Parameters understood by the system and service
  77           manager to control system behavior. For details, see
  78           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
  79         </listitem>
  80       </varlistentry>
  81
  82       <varlistentry>
  83         <term><varname>systemd.mask=</varname></term>
  84         <term><varname>systemd.wants=</varname></term>
  85         <term><varname>systemd.debug_shell</varname></term>
  86         <listitem>
  87           <para>Additional parameters understood by
  88           <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
  89           to mask or start specific units at boot, or invoke a debug
  90           shell on tty9.</para>
  91         </listitem>
  92       </varlistentry>
  93
  94       <varlistentry>
  95         <term><varname>systemd.run=</varname></term>
  96         <term><varname>systemd.run_success_action=</varname></term>
  97         <term><varname>systemd.run_failure_action=</varname></term>
  98         <listitem>
  99           <para>Additional parameters understood by
 100           <citerefentry><refentrytitle>systemd-run-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, to
 101           run a command line specified on the kernel command line as system service after booting up.</para>
 102         </listitem>
 103       </varlistentry>
 104
 105       <varlistentry>
 106         <term><varname>systemd.early_core_pattern=</varname></term>
 107         <listitem>
 108           <para>During early boot, the generation of core dump files is disabled until a core dump handler (if any)
 109           takes over. This parameter allows to specifies an absolute path where core dump files should be stored until
 110           a handler is installed. The path should be absolute and may contain specifiers, see
 111           <citerefentry><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details.</para>
 112         </listitem>
 113       </varlistentry>
 114
 115       <varlistentry>
 116         <term><varname>systemd.restore_state=</varname></term>
 117         <listitem>
 118           <para>This parameter is understood by several system tools
 119           to control whether or not they should restore system state
 120           from the previous boot. For details, see
 121           <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 122           and
 123           <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 124           </para>
 125         </listitem>
 126       </varlistentry>
 127
 128       <varlistentry>
 129         <term><varname>systemd.volatile=</varname></term>
 130         <listitem>
 131           <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
 132           the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root
 133           directory and <filename>/var</filename> are mounted as specified on the kernel command line or
 134           <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
 135           this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only
 136           <filename>/usr</filename> is mounted from the file system configured as root device, in read-only mode. This
 137           enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
 138           configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as
 139           well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
 140           setting is set to <literal>state</literal> the root file system is mounted read-only, however
 141           <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
 142           system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. If
 143           this setting is set to <literal>overlay</literal> the root file system is set up as
 144           <literal>overlayfs</literal> mount combining the read-only root directory with a writable
 145           <literal>tmpfs</literal>, so that no modifications are made to disk, but the file system may be modified
 146           nonetheless with all changes being lost at reboot. For details, see
 147           <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 148           and
 149           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 150         </listitem>
 151       </varlistentry>
 152
 153       <varlistentry>
 154         <term><varname>quiet</varname></term>
 155         <listitem>
 156           <para>Parameter understood by both the kernel and the system
 157           and service manager to control console log verbosity. For
 158           details, see
 159           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 160         </listitem>
 161       </varlistentry>
 162
 163       <varlistentry>
 164         <term><varname>debug</varname></term>
 165         <listitem>
 166           <para>Parameter understood by both the kernel and the system
 167           and service manager to control console log verbosity. For
 168           details, see
 169           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 170         </listitem>
 171       </varlistentry>
 172
 173       <varlistentry>
 174         <term><varname>-b</varname></term>
 175         <term><varname>rd.emergency</varname></term>
 176         <term><varname>emergency</varname></term>
 177         <term><varname>rd.rescue</varname></term>
 178         <term><varname>rescue</varname></term>
 179         <term><varname>single</varname></term>
 180         <term><varname>s</varname></term>
 181         <term><varname>S</varname></term>
 182         <term><varname>1</varname></term>
 183         <term><varname>2</varname></term>
 184         <term><varname>3</varname></term>
 185         <term><varname>4</varname></term>
 186         <term><varname>5</varname></term>
 187         <listitem>
 188           <para>Parameters understood by the system and service
 189           manager, as compatibility and convenience options. For details, see
 190           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 191         </listitem>
 192       </varlistentry>
 193
 194       <varlistentry>
 195         <term><varname>locale.LANG=</varname></term>
 196         <term><varname>locale.LANGUAGE=</varname></term>
 197         <term><varname>locale.LC_CTYPE=</varname></term>
 198         <term><varname>locale.LC_NUMERIC=</varname></term>
 199         <term><varname>locale.LC_TIME=</varname></term>
 200         <term><varname>locale.LC_COLLATE=</varname></term>
 201         <term><varname>locale.LC_MONETARY=</varname></term>
 202         <term><varname>locale.LC_MESSAGES=</varname></term>
 203         <term><varname>locale.LC_PAPER=</varname></term>
 204         <term><varname>locale.LC_NAME=</varname></term>
 205         <term><varname>locale.LC_ADDRESS=</varname></term>
 206         <term><varname>locale.LC_TELEPHONE=</varname></term>
 207         <term><varname>locale.LC_MEASUREMENT=</varname></term>
 208         <term><varname>locale.LC_IDENTIFICATION=</varname></term>
 209         <listitem>
 210           <para>Parameters understood by the system and service
 211           manager to control locale and language settings. For
 212           details, see
 213           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 214         </listitem>
 215       </varlistentry>
 216
 217       <varlistentry>
 218         <term><varname>fsck.mode=</varname></term>
 219         <term><varname>fsck.repair=</varname></term>
 220
 221         <listitem>
 222           <para>Parameters understood by the file system checker
 223           services. For details, see
 224           <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 225         </listitem>
 226       </varlistentry>
 227
 228       <varlistentry>
 229         <term><varname>quotacheck.mode=</varname></term>
 230
 231         <listitem>
 232           <para>Parameter understood by the file quota checker
 233           service. For details, see
 234           <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 235         </listitem>
 236       </varlistentry>
 237
 238       <varlistentry>
 239         <term><varname>systemd.journald.forward_to_syslog=</varname></term>
 240         <term><varname>systemd.journald.forward_to_kmsg=</varname></term>
 241         <term><varname>systemd.journald.forward_to_console=</varname></term>
 242         <term><varname>systemd.journald.forward_to_wall=</varname></term>
 243
 244         <listitem>
 245           <para>Parameters understood by the journal service. For
 246           details, see
 247           <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 248         </listitem>
 249       </varlistentry>
 250
 251       <varlistentry>
 252         <term><varname>vconsole.keymap=</varname></term>
 253         <term><varname>vconsole.keymap_toggle=</varname></term>
 254         <term><varname>vconsole.font=</varname></term>
 255         <term><varname>vconsole.font_map=</varname></term>
 256         <term><varname>vconsole.font_unimap=</varname></term>
 257
 258         <listitem>
 259           <para>Parameters understood by the virtual console setup logic. For details, see
 260           <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 261         </listitem>
 262       </varlistentry>
 263
 264       <varlistentry>
 265         <term><varname>udev.log_priority=</varname></term>
 266         <term><varname>rd.udev.log_priority=</varname></term>
 267         <term><varname>udev.children_max=</varname></term>
 268         <term><varname>rd.udev.children_max=</varname></term>
 269         <term><varname>udev.exec_delay=</varname></term>
 270         <term><varname>rd.udev.exec_delay=</varname></term>
 271         <term><varname>udev.event_timeout=</varname></term>
 272         <term><varname>rd.udev.event_timeout=</varname></term>
 273         <term><varname>net.ifnames=</varname></term>
 274         <term><varname>net.naming-scheme=</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-write 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><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 435         <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 436         <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 437         <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 438         <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 439         <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 440         <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 441         <citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 442         <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 443         <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 444         <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 445         <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 446         <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 447         <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 448         <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 449         <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 450         <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 451         <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 452         <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 453         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 454       </para>
 455   </refsect1>
 456
 457 </refentry>