man/kernel-command-line.xml

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   8   Copyright 2012 Lennart Poettering
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  23
  24 <refentry id="kernel-command-line">
  25
  26   <refentryinfo>
  27     <title>kernel-command-line</title>
  28     <productname>systemd</productname>
  29
  30     <authorgroup>
  31       <author>
  32         <contrib>Developer</contrib>
  33         <firstname>Lennart</firstname>
  34         <surname>Poettering</surname>
  35         <email>lennart@poettering.net</email>
  36       </author>
  37     </authorgroup>
  38   </refentryinfo>
  39
  40   <refmeta>
  41     <refentrytitle>kernel-command-line</refentrytitle>
  42     <manvolnum>7</manvolnum>
  43   </refmeta>
  44
  45   <refnamediv>
  46     <refname>kernel-command-line</refname>
  47     <refpurpose>Kernel command line parameters</refpurpose>
  48   </refnamediv>
  49
  50   <refsynopsisdiv>
  51     <para><filename>/proc/cmdline</filename></para>
  52   </refsynopsisdiv>
  53
  54   <refsect1>
  55     <title>Description</title>
  56
  57     <para>The kernel, the initial RAM disk (initrd) and
  58     basic userspace functionality may be configured at boot via
  59     kernel command line arguments.</para>
  60
  61     <para>For command line parameters understood by the kernel, please
  62     see
  63     <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink>
  64     and
  65     <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
  66
  67     <para>For command line parameters understood by the initial RAM
  68     disk, please see
  69     <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
  70     or the documentation of the specific initrd implementation of your
  71     installation.</para>
  72   </refsect1>
  73
  74   <refsect1>
  75     <title>Core OS Command Line Arguments</title>
  76
  77     <variablelist class='kernel-commandline-options'>
  78       <varlistentry>
  79         <term><varname>systemd.unit=</varname></term>
  80         <term><varname>rd.systemd.unit=</varname></term>
  81         <term><varname>systemd.dump_core</varname></term>
  82         <term><varname>systemd.crash_chvt</varname></term>
  83         <term><varname>systemd.crash_shell</varname></term>
  84         <term><varname>systemd.crash_reboot</varname></term>
  85         <term><varname>systemd.confirm_spawn</varname></term>
  86         <term><varname>systemd.show_status</varname></term>
  87         <term><varname>systemd.log_target=</varname></term>
  88         <term><varname>systemd.log_level=</varname></term>
  89         <term><varname>systemd.log_location=</varname></term>
  90         <term><varname>systemd.log_color</varname></term>
  91         <term><varname>systemd.default_standard_output=</varname></term>
  92         <term><varname>systemd.default_standard_error=</varname></term>
  93         <term><varname>systemd.setenv=</varname></term>
  94         <term><varname>systemd.machine_id=</varname></term>
  95         <term><varname>systemd.unified_cgroup_hierarchy</varname></term>
  96         <term><varname>systemd.legacy_systemd_cgroup_controller</varname></term>
  97         <listitem>
  98           <para>Parameters understood by the system and service
  99           manager to control system behavior. For details, see
 100           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 101         </listitem>
 102       </varlistentry>
 103
 104       <varlistentry>
 105         <term><varname>systemd.mask=</varname></term>
 106         <term><varname>systemd.wants=</varname></term>
 107         <term><varname>systemd.debug_shell</varname></term>
 108         <listitem>
 109           <para>Additional parameters understood by
 110           <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 111           to mask or start specific units at boot, or invoke a debug
 112           shell on tty9.</para>
 113         </listitem>
 114       </varlistentry>
 115
 116       <varlistentry>
 117         <term><varname>systemd.restore_state=</varname></term>
 118         <listitem>
 119           <para>This parameter is understood by several system tools
 120           to control whether or not they should restore system state
 121           from the previous boot. For details, see
 122           <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 123           and
 124           <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 125           </para>
 126         </listitem>
 127       </varlistentry>
 128
 129       <varlistentry>
 130         <term><varname>systemd.volatile=</varname></term>
 131         <listitem>
 132           <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
 133           the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root
 134           directory and <filename>/var</filename> are mounted as specified on the kernel command line or
 135           <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
 136           this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only
 137           <filename>/usr</filename> is mounted from the file system configured as root device, in read-only mode. This
 138           enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
 139           configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as
 140           well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
 141           setting is set to <literal>state</literal> the root file system is mounted as usual, however
 142           <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
 143           system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
 144           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
 273         <listitem>
 274           <para>Parameters understood by the device event managing
 275           daemon. For details, see
 276           <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 277         </listitem>
 278       </varlistentry>
 279
 280       <varlistentry>
 281         <term><varname>plymouth.enable=</varname></term>
 282
 283         <listitem>
 284           <para>May be used to disable the Plymouth boot splash. For
 285           details, see
 286           <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 287         </listitem>
 288       </varlistentry>
 289
 290       <varlistentry>
 291         <term><varname>luks=</varname></term>
 292         <term><varname>rd.luks=</varname></term>
 293         <term><varname>luks.crypttab=</varname></term>
 294         <term><varname>rd.luks.crypttab=</varname></term>
 295         <term><varname>luks.name=</varname></term>
 296         <term><varname>rd.luks.name=</varname></term>
 297         <term><varname>luks.uuid=</varname></term>
 298         <term><varname>rd.luks.uuid=</varname></term>
 299         <term><varname>luks.options=</varname></term>
 300         <term><varname>rd.luks.options=</varname></term>
 301         <term><varname>luks.key=</varname></term>
 302         <term><varname>rd.luks.key=</varname></term>
 303
 304         <listitem>
 305           <para>Configures the LUKS full-disk encryption logic at
 306           boot. For details, see
 307           <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 308         </listitem>
 309       </varlistentry>
 310
 311       <varlistentry>
 312         <term><varname>fstab=</varname></term>
 313         <term><varname>rd.fstab=</varname></term>
 314
 315         <listitem>
 316           <para>Configures the <filename>/etc/fstab</filename> logic
 317           at boot. For details, see
 318           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 319         </listitem>
 320       </varlistentry>
 321
 322       <varlistentry>
 323         <term><varname>root=</varname></term>
 324         <term><varname>rootfstype=</varname></term>
 325         <term><varname>rootflags=</varname></term>
 326         <term><varname>ro</varname></term>
 327         <term><varname>rw</varname></term>
 328
 329         <listitem>
 330           <para>Configures the root file system and its file system
 331           type and mount options, as well as whether it shall be
 332           mounted read-only or read-writable initially. For details,
 333           see
 334           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 335         </listitem>
 336       </varlistentry>
 337
 338       <varlistentry>
 339         <term><varname>roothash=</varname></term>
 340         <term><varname>systemd.verity=</varname></term>
 341         <term><varname>rd.systemd.verity=</varname></term>
 342         <term><varname>systemd.verity_root_data=</varname></term>
 343         <term><varname>systemd.verity_root_hash=</varname></term>
 344         <listitem>
 345           <para>Configures the integrity protection root hash for the root file system, and other related
 346           parameters. For details, see
 347           <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 348         </listitem>
 349       </varlistentry>
 350
 351       <varlistentry>
 352         <term><varname>systemd.gpt_auto=</varname></term>
 353         <term><varname>rd.systemd.gpt_auto=</varname></term>
 354
 355         <listitem>
 356           <para>Configures whether GPT based partition auto-discovery
 357           shall be attempted. For details, see
 358           <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 359         </listitem>
 360       </varlistentry>
 361
 362       <varlistentry>
 363         <term><varname>systemd.default_timeout_start_sec=</varname></term>
 364
 365         <listitem>
 366           <para>Overwrites the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at boot. For details,
 367           see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 368         </listitem>
 369       </varlistentry>
 370
 371       <varlistentry>
 372         <term><varname>modules_load=</varname></term>
 373         <term><varname>rd.modules_load=</varname></term>
 374
 375         <listitem>
 376           <para>Load a specific kernel module early at boot. For
 377           details, see
 378           <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 379         </listitem>
 380       </varlistentry>
 381
 382       <varlistentry>
 383         <term><varname>resume=</varname></term>
 384
 385         <listitem>
 386           <para>Enables resume from hibernation using the specified
 387           device. All
 388           <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
 389           paths are supported. For details, see
 390           <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 391         </listitem>
 392       </varlistentry>
 393
 394       <varlistentry>
 395         <term><varname>systemd.firstboot=</varname></term>
 396
 397         <listitem><para>Takes a boolean argument, defaults to on. If off,
 398         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 399         will not query the user for basic system settings, even if the system boots up for the first time and the
 400         relevant settings are not initialized yet.</para></listitem>
 401       </varlistentry>
 402     </variablelist>
 403
 404   </refsect1>
 405
 406   <refsect1>
 407       <title>See Also</title>
 408       <para>
 409         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 410         <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 411         <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 412         <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 413         <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 414         <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 415         <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 416         <citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 417         <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 418         <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 419         <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 420         <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 421         <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 422         <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 423         <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 424         <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 425         <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 426         <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 427         <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 428         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 429       </para>
 430   </refsect1>
 431
 432 </refentry>