man/kernel-command-line.xml

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   6   SPDX-License-Identifier: LGPL-2.1+
   7
   8   This file is part of systemd.
   9
  10   Copyright 2012 Lennart Poettering
  11 -->
  12
  13 <refentry id="kernel-command-line">
  14
  15   <refentryinfo>
  16     <title>kernel-command-line</title>
  17     <productname>systemd</productname>
  18
  19     <authorgroup>
  20       <author>
  21         <contrib>Developer</contrib>
  22         <firstname>Lennart</firstname>
  23         <surname>Poettering</surname>
  24         <email>lennart@poettering.net</email>
  25       </author>
  26     </authorgroup>
  27   </refentryinfo>
  28
  29   <refmeta>
  30     <refentrytitle>kernel-command-line</refentrytitle>
  31     <manvolnum>7</manvolnum>
  32   </refmeta>
  33
  34   <refnamediv>
  35     <refname>kernel-command-line</refname>
  36     <refpurpose>Kernel command line parameters</refpurpose>
  37   </refnamediv>
  38
  39   <refsynopsisdiv>
  40     <para><filename>/proc/cmdline</filename></para>
  41   </refsynopsisdiv>
  42
  43   <refsect1>
  44     <title>Description</title>
  45
  46     <para>The kernel, the initial RAM disk (initrd) and
  47     basic userspace functionality may be configured at boot via
  48     kernel command line arguments.</para>
  49
  50     <para>For command line parameters understood by the kernel, please
  51     see
  52     <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink>
  53     and
  54     <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
  55
  56     <para>For command line parameters understood by the initial RAM
  57     disk, please see
  58     <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
  59     or the documentation of the specific initrd implementation of your
  60     installation.</para>
  61   </refsect1>
  62
  63   <refsect1>
  64     <title>Core OS Command Line Arguments</title>
  65
  66     <variablelist class='kernel-commandline-options'>
  67       <varlistentry>
  68         <term><varname>systemd.unit=</varname></term>
  69         <term><varname>rd.systemd.unit=</varname></term>
  70         <term><varname>systemd.dump_core</varname></term>
  71         <term><varname>systemd.crash_chvt</varname></term>
  72         <term><varname>systemd.crash_shell</varname></term>
  73         <term><varname>systemd.crash_reboot</varname></term>
  74         <term><varname>systemd.confirm_spawn</varname></term>
  75         <term><varname>systemd.service_watchdogs</varname></term>
  76         <term><varname>systemd.show_status</varname></term>
  77         <term><varname>systemd.log_target=</varname></term>
  78         <term><varname>systemd.log_level=</varname></term>
  79         <term><varname>systemd.log_location=</varname></term>
  80         <term><varname>systemd.log_color</varname></term>
  81         <term><varname>systemd.default_standard_output=</varname></term>
  82         <term><varname>systemd.default_standard_error=</varname></term>
  83         <term><varname>systemd.setenv=</varname></term>
  84         <term><varname>systemd.machine_id=</varname></term>
  85         <term><varname>systemd.unified_cgroup_hierarchy</varname></term>
  86         <term><varname>systemd.legacy_systemd_cgroup_controller</varname></term>
  87         <listitem>
  88           <para>Parameters understood by the system and service
  89           manager to control system behavior. For details, see
  90           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
  91         </listitem>
  92       </varlistentry>
  93
  94       <varlistentry>
  95         <term><varname>systemd.mask=</varname></term>
  96         <term><varname>systemd.wants=</varname></term>
  97         <term><varname>systemd.debug_shell</varname></term>
  98         <listitem>
  99           <para>Additional parameters understood by
 100           <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 101           to mask or start specific units at boot, or invoke a debug
 102           shell on tty9.</para>
 103         </listitem>
 104       </varlistentry>
 105
 106       <varlistentry>
 107         <term><varname>systemd.restore_state=</varname></term>
 108         <listitem>
 109           <para>This parameter is understood by several system tools
 110           to control whether or not they should restore system state
 111           from the previous boot. For details, see
 112           <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 113           and
 114           <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 115           </para>
 116         </listitem>
 117       </varlistentry>
 118
 119       <varlistentry>
 120         <term><varname>systemd.volatile=</varname></term>
 121         <listitem>
 122           <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
 123           the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root
 124           directory and <filename>/var</filename> are mounted as specified on the kernel command line or
 125           <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
 126           this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only
 127           <filename>/usr</filename> is mounted from the file system configured as root device, in read-only mode. This
 128           enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
 129           configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as
 130           well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
 131           setting is set to <literal>state</literal> the root file system is mounted as usual, however
 132           <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
 133           system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
 134           see
 135           <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 136           and
 137           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 138         </listitem>
 139       </varlistentry>
 140
 141       <varlistentry>
 142         <term><varname>quiet</varname></term>
 143         <listitem>
 144           <para>Parameter understood by both the kernel and the system
 145           and service manager to control console log verbosity. For
 146           details, see
 147           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 148         </listitem>
 149       </varlistentry>
 150
 151       <varlistentry>
 152         <term><varname>debug</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>-b</varname></term>
 163         <term><varname>rd.emergency</varname></term>
 164         <term><varname>emergency</varname></term>
 165         <term><varname>rd.rescue</varname></term>
 166         <term><varname>rescue</varname></term>
 167         <term><varname>single</varname></term>
 168         <term><varname>s</varname></term>
 169         <term><varname>S</varname></term>
 170         <term><varname>1</varname></term>
 171         <term><varname>2</varname></term>
 172         <term><varname>3</varname></term>
 173         <term><varname>4</varname></term>
 174         <term><varname>5</varname></term>
 175         <listitem>
 176           <para>Parameters understood by the system and service
 177           manager, as compatibility and convenience options. For details, see
 178           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 179         </listitem>
 180       </varlistentry>
 181
 182       <varlistentry>
 183         <term><varname>locale.LANG=</varname></term>
 184         <term><varname>locale.LANGUAGE=</varname></term>
 185         <term><varname>locale.LC_CTYPE=</varname></term>
 186         <term><varname>locale.LC_NUMERIC=</varname></term>
 187         <term><varname>locale.LC_TIME=</varname></term>
 188         <term><varname>locale.LC_COLLATE=</varname></term>
 189         <term><varname>locale.LC_MONETARY=</varname></term>
 190         <term><varname>locale.LC_MESSAGES=</varname></term>
 191         <term><varname>locale.LC_PAPER=</varname></term>
 192         <term><varname>locale.LC_NAME=</varname></term>
 193         <term><varname>locale.LC_ADDRESS=</varname></term>
 194         <term><varname>locale.LC_TELEPHONE=</varname></term>
 195         <term><varname>locale.LC_MEASUREMENT=</varname></term>
 196         <term><varname>locale.LC_IDENTIFICATION=</varname></term>
 197         <listitem>
 198           <para>Parameters understood by the system and service
 199           manager to control locale and language settings. For
 200           details, see
 201           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 202         </listitem>
 203       </varlistentry>
 204
 205       <varlistentry>
 206         <term><varname>fsck.mode=</varname></term>
 207         <term><varname>fsck.repair=</varname></term>
 208
 209         <listitem>
 210           <para>Parameters understood by the file system checker
 211           services. For details, see
 212           <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 213         </listitem>
 214       </varlistentry>
 215
 216       <varlistentry>
 217         <term><varname>quotacheck.mode=</varname></term>
 218
 219         <listitem>
 220           <para>Parameter understood by the file quota checker
 221           service. For details, see
 222           <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 223         </listitem>
 224       </varlistentry>
 225
 226       <varlistentry>
 227         <term><varname>systemd.journald.forward_to_syslog=</varname></term>
 228         <term><varname>systemd.journald.forward_to_kmsg=</varname></term>
 229         <term><varname>systemd.journald.forward_to_console=</varname></term>
 230         <term><varname>systemd.journald.forward_to_wall=</varname></term>
 231
 232         <listitem>
 233           <para>Parameters understood by the journal service. For
 234           details, see
 235           <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 236         </listitem>
 237       </varlistentry>
 238
 239       <varlistentry>
 240         <term><varname>vconsole.keymap=</varname></term>
 241         <term><varname>vconsole.keymap_toggle=</varname></term>
 242         <term><varname>vconsole.font=</varname></term>
 243         <term><varname>vconsole.font_map=</varname></term>
 244         <term><varname>vconsole.font_unimap=</varname></term>
 245
 246         <listitem>
 247           <para>Parameters understood by the virtual console setup logic. For details, see
 248           <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 249         </listitem>
 250       </varlistentry>
 251
 252       <varlistentry>
 253         <term><varname>udev.log_priority=</varname></term>
 254         <term><varname>rd.udev.log_priority=</varname></term>
 255         <term><varname>udev.children_max=</varname></term>
 256         <term><varname>rd.udev.children_max=</varname></term>
 257         <term><varname>udev.exec_delay=</varname></term>
 258         <term><varname>rd.udev.exec_delay=</varname></term>
 259         <term><varname>udev.event_timeout=</varname></term>
 260         <term><varname>rd.udev.event_timeout=</varname></term>
 261         <term><varname>net.ifnames=</varname></term>
 262
 263         <listitem>
 264           <para>Parameters understood by the device event managing
 265           daemon. For details, see
 266           <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 267         </listitem>
 268       </varlistentry>
 269
 270       <varlistentry>
 271         <term><varname>plymouth.enable=</varname></term>
 272
 273         <listitem>
 274           <para>May be used to disable the Plymouth boot splash. For
 275           details, see
 276           <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 277         </listitem>
 278       </varlistentry>
 279
 280       <varlistentry>
 281         <term><varname>luks=</varname></term>
 282         <term><varname>rd.luks=</varname></term>
 283         <term><varname>luks.crypttab=</varname></term>
 284         <term><varname>rd.luks.crypttab=</varname></term>
 285         <term><varname>luks.name=</varname></term>
 286         <term><varname>rd.luks.name=</varname></term>
 287         <term><varname>luks.uuid=</varname></term>
 288         <term><varname>rd.luks.uuid=</varname></term>
 289         <term><varname>luks.options=</varname></term>
 290         <term><varname>rd.luks.options=</varname></term>
 291         <term><varname>luks.key=</varname></term>
 292         <term><varname>rd.luks.key=</varname></term>
 293
 294         <listitem>
 295           <para>Configures the LUKS full-disk encryption logic at
 296           boot. For details, see
 297           <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 298         </listitem>
 299       </varlistentry>
 300
 301       <varlistentry>
 302         <term><varname>fstab=</varname></term>
 303         <term><varname>rd.fstab=</varname></term>
 304
 305         <listitem>
 306           <para>Configures the <filename>/etc/fstab</filename> logic
 307           at boot. For details, see
 308           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 309         </listitem>
 310       </varlistentry>
 311
 312       <varlistentry>
 313         <term><varname>root=</varname></term>
 314         <term><varname>rootfstype=</varname></term>
 315         <term><varname>rootflags=</varname></term>
 316         <term><varname>ro</varname></term>
 317         <term><varname>rw</varname></term>
 318
 319         <listitem>
 320           <para>Configures the root file system and its file system
 321           type and mount options, as well as whether it shall be
 322           mounted read-only or read-writable initially. For details,
 323           see
 324           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 325         </listitem>
 326       </varlistentry>
 327
 328       <varlistentry>
 329         <term><varname>mount.usr=</varname></term>
 330         <term><varname>mount.usrfstype=</varname></term>
 331         <term><varname>mount.usrflags=</varname></term>
 332
 333         <listitem>
 334           <para>Configures the /usr file system (if required) and
 335           its file system type and mount options. For details, see
 336           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 337         </listitem>
 338       </varlistentry>
 339
 340       <varlistentry>
 341         <term><varname>roothash=</varname></term>
 342         <term><varname>systemd.verity=</varname></term>
 343         <term><varname>rd.systemd.verity=</varname></term>
 344         <term><varname>systemd.verity_root_data=</varname></term>
 345         <term><varname>systemd.verity_root_hash=</varname></term>
 346         <listitem>
 347           <para>Configures the integrity protection root hash for the root file system, and other related
 348           parameters. For details, see
 349           <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 350         </listitem>
 351       </varlistentry>
 352
 353       <varlistentry>
 354         <term><varname>systemd.gpt_auto=</varname></term>
 355         <term><varname>rd.systemd.gpt_auto=</varname></term>
 356
 357         <listitem>
 358           <para>Configures whether GPT based partition auto-discovery
 359           shall be attempted. For details, see
 360           <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 361         </listitem>
 362       </varlistentry>
 363
 364       <varlistentry>
 365         <term><varname>systemd.default_timeout_start_sec=</varname></term>
 366
 367         <listitem>
 368           <para>Overwrites the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at boot. For details,
 369           see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 370         </listitem>
 371       </varlistentry>
 372
 373       <varlistentry>
 374         <term><varname>systemd.watchdog_device=</varname></term>
 375
 376         <listitem>
 377           <para>Overwrites the watchdog device path <varname>WatchdogDevice=</varname>. For details, see
 378           <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 379         </listitem>
 380       </varlistentry>
 381
 382       <varlistentry>
 383         <term><varname>modules_load=</varname></term>
 384         <term><varname>rd.modules_load=</varname></term>
 385
 386         <listitem>
 387           <para>Load a specific kernel module early at boot. For
 388           details, see
 389           <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 390         </listitem>
 391       </varlistentry>
 392
 393       <varlistentry>
 394         <term><varname>resume=</varname></term>
 395
 396         <listitem>
 397           <para>Enables resume from hibernation using the specified
 398           device. All
 399           <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
 400           paths are supported. For details, see
 401           <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 402         </listitem>
 403       </varlistentry>
 404
 405       <varlistentry>
 406         <term><varname>systemd.firstboot=</varname></term>
 407
 408         <listitem><para>Takes a boolean argument, defaults to on. If off,
 409         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 410         will not query the user for basic system settings, even if the system boots up for the first time and the
 411         relevant settings are not initialized yet.</para></listitem>
 412       </varlistentry>
 413     </variablelist>
 414
 415   </refsect1>
 416
 417   <refsect1>
 418       <title>See Also</title>
 419       <para>
 420         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 421         <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 422         <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 423         <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 424         <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 425         <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 426         <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 427         <citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 428         <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 429         <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 430         <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 431         <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 432         <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 433         <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 434         <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 435         <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 436         <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 437         <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 438         <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 439         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 440       </para>
 441   </refsect1>
 442
 443 </refentry>