man/kernel-command-line.xml

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  10   Copyright 2012 Lennart Poettering
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  25
  26 <refentry id="kernel-command-line">
  27
  28   <refentryinfo>
  29     <title>kernel-command-line</title>
  30     <productname>systemd</productname>
  31
  32     <authorgroup>
  33       <author>
  34         <contrib>Developer</contrib>
  35         <firstname>Lennart</firstname>
  36         <surname>Poettering</surname>
  37         <email>lennart@poettering.net</email>
  38       </author>
  39     </authorgroup>
  40   </refentryinfo>
  41
  42   <refmeta>
  43     <refentrytitle>kernel-command-line</refentrytitle>
  44     <manvolnum>7</manvolnum>
  45   </refmeta>
  46
  47   <refnamediv>
  48     <refname>kernel-command-line</refname>
  49     <refpurpose>Kernel command line parameters</refpurpose>
  50   </refnamediv>
  51
  52   <refsynopsisdiv>
  53     <para><filename>/proc/cmdline</filename></para>
  54   </refsynopsisdiv>
  55
  56   <refsect1>
  57     <title>Description</title>
  58
  59     <para>The kernel, the initial RAM disk (initrd) and
  60     basic userspace functionality may be configured at boot via
  61     kernel command line arguments.</para>
  62
  63     <para>For command line parameters understood by the kernel, please
  64     see
  65     <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink>
  66     and
  67     <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
  68
  69     <para>For command line parameters understood by the initial RAM
  70     disk, please see
  71     <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
  72     or the documentation of the specific initrd implementation of your
  73     installation.</para>
  74   </refsect1>
  75
  76   <refsect1>
  77     <title>Core OS Command Line Arguments</title>
  78
  79     <variablelist class='kernel-commandline-options'>
  80       <varlistentry>
  81         <term><varname>systemd.unit=</varname></term>
  82         <term><varname>rd.systemd.unit=</varname></term>
  83         <term><varname>systemd.dump_core</varname></term>
  84         <term><varname>systemd.crash_chvt</varname></term>
  85         <term><varname>systemd.crash_shell</varname></term>
  86         <term><varname>systemd.crash_reboot</varname></term>
  87         <term><varname>systemd.confirm_spawn</varname></term>
  88         <term><varname>systemd.show_status</varname></term>
  89         <term><varname>systemd.log_target=</varname></term>
  90         <term><varname>systemd.log_level=</varname></term>
  91         <term><varname>systemd.log_location=</varname></term>
  92         <term><varname>systemd.log_color</varname></term>
  93         <term><varname>systemd.default_standard_output=</varname></term>
  94         <term><varname>systemd.default_standard_error=</varname></term>
  95         <term><varname>systemd.setenv=</varname></term>
  96         <term><varname>systemd.machine_id=</varname></term>
  97         <term><varname>systemd.unified_cgroup_hierarchy</varname></term>
  98         <term><varname>systemd.legacy_systemd_cgroup_controller</varname></term>
  99         <listitem>
 100           <para>Parameters understood by the system and service
 101           manager to control system behavior. For details, see
 102           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 103         </listitem>
 104       </varlistentry>
 105
 106       <varlistentry>
 107         <term><varname>systemd.mask=</varname></term>
 108         <term><varname>systemd.wants=</varname></term>
 109         <term><varname>systemd.debug_shell</varname></term>
 110         <listitem>
 111           <para>Additional parameters understood by
 112           <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 113           to mask or start specific units at boot, or invoke a debug
 114           shell on tty9.</para>
 115         </listitem>
 116       </varlistentry>
 117
 118       <varlistentry>
 119         <term><varname>systemd.restore_state=</varname></term>
 120         <listitem>
 121           <para>This parameter is understood by several system tools
 122           to control whether or not they should restore system state
 123           from the previous boot. For details, see
 124           <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 125           and
 126           <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 127           </para>
 128         </listitem>
 129       </varlistentry>
 130
 131       <varlistentry>
 132         <term><varname>systemd.volatile=</varname></term>
 133         <listitem>
 134           <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
 135           the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root
 136           directory and <filename>/var</filename> are mounted as specified on the kernel command line or
 137           <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
 138           this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only
 139           <filename>/usr</filename> is mounted from the file system configured as root device, in read-only mode. This
 140           enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
 141           configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as
 142           well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
 143           setting is set to <literal>state</literal> the root file system is mounted as usual, however
 144           <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
 145           system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
 146           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
 275         <listitem>
 276           <para>Parameters understood by the device event managing
 277           daemon. For details, see
 278           <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 279         </listitem>
 280       </varlistentry>
 281
 282       <varlistentry>
 283         <term><varname>plymouth.enable=</varname></term>
 284
 285         <listitem>
 286           <para>May be used to disable the Plymouth boot splash. For
 287           details, see
 288           <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 289         </listitem>
 290       </varlistentry>
 291
 292       <varlistentry>
 293         <term><varname>luks=</varname></term>
 294         <term><varname>rd.luks=</varname></term>
 295         <term><varname>luks.crypttab=</varname></term>
 296         <term><varname>rd.luks.crypttab=</varname></term>
 297         <term><varname>luks.name=</varname></term>
 298         <term><varname>rd.luks.name=</varname></term>
 299         <term><varname>luks.uuid=</varname></term>
 300         <term><varname>rd.luks.uuid=</varname></term>
 301         <term><varname>luks.options=</varname></term>
 302         <term><varname>rd.luks.options=</varname></term>
 303         <term><varname>luks.key=</varname></term>
 304         <term><varname>rd.luks.key=</varname></term>
 305
 306         <listitem>
 307           <para>Configures the LUKS full-disk encryption logic at
 308           boot. For details, see
 309           <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 310         </listitem>
 311       </varlistentry>
 312
 313       <varlistentry>
 314         <term><varname>fstab=</varname></term>
 315         <term><varname>rd.fstab=</varname></term>
 316
 317         <listitem>
 318           <para>Configures the <filename>/etc/fstab</filename> logic
 319           at boot. For details, see
 320           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 321         </listitem>
 322       </varlistentry>
 323
 324       <varlistentry>
 325         <term><varname>root=</varname></term>
 326         <term><varname>rootfstype=</varname></term>
 327         <term><varname>rootflags=</varname></term>
 328         <term><varname>ro</varname></term>
 329         <term><varname>rw</varname></term>
 330
 331         <listitem>
 332           <para>Configures the root file system and its file system
 333           type and mount options, as well as whether it shall be
 334           mounted read-only or read-writable initially. For details,
 335           see
 336           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 337         </listitem>
 338       </varlistentry>
 339
 340       <varlistentry>
 341         <term><varname>mount.usr=</varname></term>
 342         <term><varname>mount.usrfstype=</varname></term>
 343         <term><varname>mount.usrflags=</varname></term>
 344
 345         <listitem>
 346           <para>Configures the /usr file system (if required) and
 347           its file system type and mount options. For details, see
 348           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 349         </listitem>
 350       </varlistentry>
 351
 352       <varlistentry>
 353         <term><varname>roothash=</varname></term>
 354         <term><varname>systemd.verity=</varname></term>
 355         <term><varname>rd.systemd.verity=</varname></term>
 356         <term><varname>systemd.verity_root_data=</varname></term>
 357         <term><varname>systemd.verity_root_hash=</varname></term>
 358         <listitem>
 359           <para>Configures the integrity protection root hash for the root file system, and other related
 360           parameters. For details, see
 361           <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 362         </listitem>
 363       </varlistentry>
 364
 365       <varlistentry>
 366         <term><varname>systemd.gpt_auto=</varname></term>
 367         <term><varname>rd.systemd.gpt_auto=</varname></term>
 368
 369         <listitem>
 370           <para>Configures whether GPT based partition auto-discovery
 371           shall be attempted. For details, see
 372           <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 373         </listitem>
 374       </varlistentry>
 375
 376       <varlistentry>
 377         <term><varname>systemd.default_timeout_start_sec=</varname></term>
 378
 379         <listitem>
 380           <para>Overwrites the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at boot. For details,
 381           see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 382         </listitem>
 383       </varlistentry>
 384
 385       <varlistentry>
 386         <term><varname>modules_load=</varname></term>
 387         <term><varname>rd.modules_load=</varname></term>
 388
 389         <listitem>
 390           <para>Load a specific kernel module early at boot. For
 391           details, see
 392           <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 393         </listitem>
 394       </varlistentry>
 395
 396       <varlistentry>
 397         <term><varname>resume=</varname></term>
 398
 399         <listitem>
 400           <para>Enables resume from hibernation using the specified
 401           device. All
 402           <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
 403           paths are supported. For details, see
 404           <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 405         </listitem>
 406       </varlistentry>
 407
 408       <varlistentry>
 409         <term><varname>systemd.firstboot=</varname></term>
 410
 411         <listitem><para>Takes a boolean argument, defaults to on. If off,
 412         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 413         will not query the user for basic system settings, even if the system boots up for the first time and the
 414         relevant settings are not initialized yet.</para></listitem>
 415       </varlistentry>
 416     </variablelist>
 417
 418   </refsect1>
 419
 420   <refsect1>
 421       <title>See Also</title>
 422       <para>
 423         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 424         <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 425         <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 426         <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 427         <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 428         <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 429         <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 430         <citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 431         <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 432         <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 433         <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 434         <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 435         <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 436         <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 437         <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 438         <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 439         <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 440         <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 441         <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 442         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 443       </para>
 444   </refsect1>
 445
 446 </refentry>