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 <ulink
  63     url="https://www.kernel.org/doc/Documentation/kernel-parameters.txt"><filename>kernel-parameters.txt</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_color=</varname></term>
  90         <term><varname>systemd.log_location=</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         <listitem>
  96           <para>Parameters understood by the system and service
  97           manager to control system behavior. For details, see
  98           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
  99         </listitem>
 100       </varlistentry>
 101
 102       <varlistentry>
 103         <term><varname>systemd.mask=</varname></term>
 104         <term><varname>systemd.wants=</varname></term>
 105         <term><varname>systemd.debug_shell</varname></term>
 106         <listitem>
 107           <para>Additional parameters understood by
 108           <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 109           to mask or start specific units at boot, or invoke a debug
 110           shell on tty9.</para>
 111         </listitem>
 112       </varlistentry>
 113
 114       <varlistentry>
 115         <term><varname>systemd.restore_state=</varname></term>
 116         <listitem>
 117           <para>This parameter is understood by several system tools
 118           to control whether or not they should restore system state
 119           from the previous boot. For details, see
 120           <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 121           and
 122           <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.
 123           </para>
 124         </listitem>
 125       </varlistentry>
 126
 127       <varlistentry>
 128         <term><varname>systemd.volatile=</varname></term>
 129         <listitem>
 130           <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or
 131           the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root
 132           directory and <filename>/var</filename> are mounted as specified on the kernel command line or
 133           <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In
 134           this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only
 135           <filename>/usr</filename> is mounted from the file system configured as root device, in read-only mode. This
 136           enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default
 137           configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as
 138           well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this
 139           setting is set to <literal>state</literal> the root file system is mounted as usual, however
 140           <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the
 141           system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. For details,
 142           see
 143           <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 144           and
 145           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 146         </listitem>
 147       </varlistentry>
 148
 149       <varlistentry>
 150         <term><varname>quiet</varname></term>
 151         <listitem>
 152           <para>Parameter understood by both the kernel and the system
 153           and service manager to control console log verbosity. For
 154           details, see
 155           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 156         </listitem>
 157       </varlistentry>
 158
 159       <varlistentry>
 160         <term><varname>debug</varname></term>
 161         <listitem>
 162           <para>Parameter understood by both the kernel and the system
 163           and service manager to control console log verbosity. For
 164           details, see
 165           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 166         </listitem>
 167       </varlistentry>
 168
 169       <varlistentry>
 170         <term><varname>-b</varname></term>
 171         <term><varname>rd.emergency</varname></term>
 172         <term><varname>emergency</varname></term>
 173         <term><varname>rd.rescue</varname></term>
 174         <term><varname>rescue</varname></term>
 175         <term><varname>single</varname></term>
 176         <term><varname>s</varname></term>
 177         <term><varname>S</varname></term>
 178         <term><varname>1</varname></term>
 179         <term><varname>2</varname></term>
 180         <term><varname>3</varname></term>
 181         <term><varname>4</varname></term>
 182         <term><varname>5</varname></term>
 183         <listitem>
 184           <para>Parameters understood by the system and service
 185           manager, as compatibility and convenience options. For details, see
 186           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 187         </listitem>
 188       </varlistentry>
 189
 190       <varlistentry>
 191         <term><varname>locale.LANG=</varname></term>
 192         <term><varname>locale.LANGUAGE=</varname></term>
 193         <term><varname>locale.LC_CTYPE=</varname></term>
 194         <term><varname>locale.LC_NUMERIC=</varname></term>
 195         <term><varname>locale.LC_TIME=</varname></term>
 196         <term><varname>locale.LC_COLLATE=</varname></term>
 197         <term><varname>locale.LC_MONETARY=</varname></term>
 198         <term><varname>locale.LC_MESSAGES=</varname></term>
 199         <term><varname>locale.LC_PAPER=</varname></term>
 200         <term><varname>locale.LC_NAME=</varname></term>
 201         <term><varname>locale.LC_ADDRESS=</varname></term>
 202         <term><varname>locale.LC_TELEPHONE=</varname></term>
 203         <term><varname>locale.LC_MEASUREMENT=</varname></term>
 204         <term><varname>locale.LC_IDENTIFICATION=</varname></term>
 205         <listitem>
 206           <para>Parameters understood by the system and service
 207           manager to control locale and language settings. For
 208           details, see
 209           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 210         </listitem>
 211       </varlistentry>
 212
 213       <varlistentry>
 214         <term><varname>fsck.mode=</varname></term>
 215         <term><varname>fsck.repair=</varname></term>
 216
 217         <listitem>
 218           <para>Parameters understood by the file system checker
 219           services. For details, see
 220           <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 221         </listitem>
 222       </varlistentry>
 223
 224       <varlistentry>
 225         <term><varname>quotacheck.mode=</varname></term>
 226
 227         <listitem>
 228           <para>Parameter understood by the file quota checker
 229           service. For details, see
 230           <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 231         </listitem>
 232       </varlistentry>
 233
 234       <varlistentry>
 235         <term><varname>systemd.journald.forward_to_syslog=</varname></term>
 236         <term><varname>systemd.journald.forward_to_kmsg=</varname></term>
 237         <term><varname>systemd.journald.forward_to_console=</varname></term>
 238         <term><varname>systemd.journald.forward_to_wall=</varname></term>
 239
 240         <listitem>
 241           <para>Parameters understood by the journal service. For
 242           details, see
 243           <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 244         </listitem>
 245       </varlistentry>
 246
 247       <varlistentry>
 248         <term><varname>vconsole.keymap=</varname></term>
 249         <term><varname>vconsole.keymap_toggle=</varname></term>
 250         <term><varname>vconsole.font=</varname></term>
 251         <term><varname>vconsole.font_map=</varname></term>
 252         <term><varname>vconsole.font_unimap=</varname></term>
 253
 254         <listitem>
 255           <para>Parameters understood by the virtual console setup logic. For details, see
 256           <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
 257         </listitem>
 258       </varlistentry>
 259
 260       <varlistentry>
 261         <term><varname>udev.log_priority=</varname></term>
 262         <term><varname>rd.udev.log_priority=</varname></term>
 263         <term><varname>udev.children_max=</varname></term>
 264         <term><varname>rd.udev.children_max=</varname></term>
 265         <term><varname>udev.exec_delay=</varname></term>
 266         <term><varname>rd.udev.exec_delay=</varname></term>
 267         <term><varname>udev.event_timeout=</varname></term>
 268         <term><varname>rd.udev.event_timeout=</varname></term>
 269         <term><varname>net.ifnames=</varname></term>
 270
 271         <listitem>
 272           <para>Parameters understood by the device event managing
 273           daemon. For details, see
 274           <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 275         </listitem>
 276       </varlistentry>
 277
 278       <varlistentry>
 279         <term><varname>plymouth.enable=</varname></term>
 280
 281         <listitem>
 282           <para>May be used to disable the Plymouth boot splash. For
 283           details, see
 284           <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 285         </listitem>
 286       </varlistentry>
 287
 288       <varlistentry>
 289         <term><varname>luks=</varname></term>
 290         <term><varname>rd.luks=</varname></term>
 291         <term><varname>luks.crypttab=</varname></term>
 292         <term><varname>rd.luks.crypttab=</varname></term>
 293         <term><varname>luks.name=</varname></term>
 294         <term><varname>rd.luks.name=</varname></term>
 295         <term><varname>luks.uuid=</varname></term>
 296         <term><varname>rd.luks.uuid=</varname></term>
 297         <term><varname>luks.options=</varname></term>
 298         <term><varname>rd.luks.options=</varname></term>
 299         <term><varname>luks.key=</varname></term>
 300         <term><varname>rd.luks.key=</varname></term>
 301
 302         <listitem>
 303           <para>Configures the LUKS full-disk encryption logic at
 304           boot. For details, see
 305           <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 306         </listitem>
 307       </varlistentry>
 308
 309       <varlistentry>
 310         <term><varname>fstab=</varname></term>
 311         <term><varname>rd.fstab=</varname></term>
 312
 313         <listitem>
 314           <para>Configures the <filename>/etc/fstab</filename> logic
 315           at boot. For details, see
 316           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 317         </listitem>
 318       </varlistentry>
 319
 320       <varlistentry>
 321         <term><varname>root=</varname></term>
 322         <term><varname>rootfstype=</varname></term>
 323         <term><varname>rootflags=</varname></term>
 324         <term><varname>ro</varname></term>
 325         <term><varname>rw</varname></term>
 326
 327         <listitem>
 328           <para>Configures the root file system and its file system
 329           type and mount options, as well as whether it shall be
 330           mounted read-only or read-writable initially. For details,
 331           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>modules_load=</varname></term>
 371         <term><varname>rd.modules_load=</varname></term>
 372
 373         <listitem>
 374           <para>Load a specific kernel module early at boot. For
 375           details, see
 376           <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 377         </listitem>
 378       </varlistentry>
 379
 380       <varlistentry>
 381         <term><varname>resume=</varname></term>
 382
 383         <listitem>
 384           <para>Enables resume from hibernation using the specified
 385           device. All
 386           <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like
 387           paths are supported. For details, see
 388           <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para>
 389         </listitem>
 390       </varlistentry>
 391
 392       <varlistentry>
 393         <term><varname>systemd.firstboot=</varname></term>
 394
 395         <listitem><para>Takes a boolean argument, defaults to on. If off,
 396         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 397         will not query the user for basic system settings, even if the system boots up for the first time and the
 398         relevant settings are not initialized yet.</para></listitem>
 399       </varlistentry>
 400     </variablelist>
 401
 402   </refsect1>
 403
 404   <refsect1>
 405       <title>See Also</title>
 406       <para>
 407         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 408         <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 409         <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
 410         <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 411         <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 412         <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 413         <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 414         <citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 415         <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 416         <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 417         <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 418         <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 419         <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 420         <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 421         <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 422         <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 423         <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 424         <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 425         <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 426         <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 427       </para>
 428   </refsect1>
 429
 430 </refentry>