| <?xml version='1.0'?> <!--*-nxml-*--> |
| <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN" |
| "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
| <!-- SPDX-License-Identifier: LGPL-2.1+ --> |
| |
| <refentry id="kernel-command-line"> |
| |
| <refentryinfo> |
| <title>kernel-command-line</title> |
| <productname>systemd</productname> |
| </refentryinfo> |
| |
| <refmeta> |
| <refentrytitle>kernel-command-line</refentrytitle> |
| <manvolnum>7</manvolnum> |
| </refmeta> |
| |
| <refnamediv> |
| <refname>kernel-command-line</refname> |
| <refpurpose>Kernel command line parameters</refpurpose> |
| </refnamediv> |
| |
| <refsynopsisdiv> |
| <para><filename>/proc/cmdline</filename></para> |
| </refsynopsisdiv> |
| |
| <refsect1> |
| <title>Description</title> |
| |
| <para>The kernel, the initial RAM disk (initrd) and basic userspace functionality may be configured at |
| boot via kernel command line arguments. In addition, various systemd tools look at the EFI variable |
| <literal>SystemdOptions</literal> (if available). Both sources are combined, but the kernel command line |
| has higher priority. Please note that <emphasis>the EFI variable is only used by systemd tools, and is |
| ignored by the kernel and other user space tools</emphasis>, so it is not a replacement for the kernel |
| command line.</para> |
| |
| <para>For command line parameters understood by the kernel, please |
| see |
| <ulink url="https://www.kernel.org/doc/html/latest/admin-guide/kernel-parameters.html"><filename>kernel-parameters.html</filename></ulink> |
| and |
| <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para> |
| |
| <para>For command line parameters understood by the initial RAM |
| disk, please see |
| <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
| or the documentation of the specific initrd implementation of your |
| installation.</para> |
| </refsect1> |
| |
| <refsect1> |
| <title>Core OS Command Line Arguments</title> |
| |
| <variablelist class='kernel-commandline-options'> |
| <varlistentry> |
| <term><varname>systemd.unit=</varname></term> |
| <term><varname>rd.systemd.unit=</varname></term> |
| <term><varname>systemd.dump_core</varname></term> |
| <term><varname>systemd.early_core_pattern=</varname></term> |
| <term><varname>systemd.crash_chvt</varname></term> |
| <term><varname>systemd.crash_shell</varname></term> |
| <term><varname>systemd.crash_reboot</varname></term> |
| <term><varname>systemd.confirm_spawn</varname></term> |
| <term><varname>systemd.service_watchdogs</varname></term> |
| <term><varname>systemd.show_status</varname></term> |
| <term><varname>systemd.status_unit_format=</varname></term> |
| <term><varname>systemd.log_target=</varname></term> |
| <term><varname>systemd.log_level=</varname></term> |
| <term><varname>systemd.log_location=</varname></term> |
| <term><varname>systemd.log_color</varname></term> |
| <term><varname>systemd.default_standard_output=</varname></term> |
| <term><varname>systemd.default_standard_error=</varname></term> |
| <term><varname>systemd.setenv=</varname></term> |
| <term><varname>systemd.machine_id=</varname></term> |
| <term><varname>systemd.unified_cgroup_hierarchy</varname></term> |
| <term><varname>systemd.legacy_systemd_cgroup_controller</varname></term> |
| <listitem> |
| <para>Parameters understood by the system and service |
| manager to control system behavior. For details, see |
| <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.mask=</varname></term> |
| <term><varname>systemd.wants=</varname></term> |
| <term><varname>systemd.debug_shell</varname></term> |
| <listitem> |
| <para>Additional parameters understood by |
| <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| to mask or start specific units at boot, or invoke a debug |
| shell on tty9.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.run=</varname></term> |
| <term><varname>systemd.run_success_action=</varname></term> |
| <term><varname>systemd.run_failure_action=</varname></term> |
| <listitem> |
| <para>Additional parameters understood by |
| <citerefentry><refentrytitle>systemd-run-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, to |
| run a command line specified on the kernel command line as system service after booting up.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.early_core_pattern=</varname></term> |
| <listitem> |
| <para>During early boot, the generation of core dump files is disabled until a core dump handler (if any) |
| takes over. This parameter allows specifying an absolute path where core dump files should be stored until |
| a handler is installed. The path should be absolute and may contain specifiers, see |
| <citerefentry><refentrytitle>core</refentrytitle><manvolnum>5</manvolnum></citerefentry> for details.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.restore_state=</varname></term> |
| <listitem> |
| <para>This parameter is understood by several system tools |
| to control whether or not they should restore system state |
| from the previous boot. For details, see |
| <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
| and |
| <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>. |
| </para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.volatile=</varname></term> |
| <listitem> |
| <para>This parameter controls whether the system shall boot up in volatile mode. Takes a boolean argument, or |
| the special value <literal>state</literal>. If false (the default), normal boot mode is selected, the root |
| directory and <filename>/var</filename> are mounted as specified on the kernel command line or |
| <filename>/etc/fstab</filename>, or otherwise configured. If true, full state-less boot mode is selected. In |
| this case the root directory is mounted as volatile memory file system (<literal>tmpfs</literal>), and only |
| <filename>/usr</filename> is mounted from the file system configured as root device, in read-only mode. This |
| enables fully state-less boots were the vendor-supplied OS is used as shipped, with only default |
| configuration and no stored state in effect, as <filename>/etc</filename> and <filename>/var</filename> (as |
| well as all other resources shipped in the root file system) are reset at boot and lost on shutdown. If this |
| setting is set to <literal>state</literal> the root file system is mounted read-only, however |
| <filename>/var</filename> is mounted as a volatile memory file system (<literal>tmpfs</literal>), so that the |
| system boots up with the normal configuration applied, but all state reset at boot and lost at shutdown. If |
| this setting is set to <literal>overlay</literal> the root file system is set up as |
| <literal>overlayfs</literal> mount combining the read-only root directory with a writable |
| <literal>tmpfs</literal>, so that no modifications are made to disk, but the file system may be modified |
| nonetheless with all changes being lost at reboot. For details, see |
| <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
| and |
| <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>quiet</varname></term> |
| <listitem> |
| <para>Parameter understood by both the kernel and the system |
| and service manager to control console log verbosity. For |
| details, see |
| <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>debug</varname></term> |
| <listitem> |
| <para>Parameter understood by both the kernel and the system |
| and service manager to control console log verbosity. For |
| details, see |
| <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>-b</varname></term> |
| <term><varname>rd.emergency</varname></term> |
| <term><varname>emergency</varname></term> |
| <term><varname>rd.rescue</varname></term> |
| <term><varname>rescue</varname></term> |
| <term><varname>single</varname></term> |
| <term><varname>s</varname></term> |
| <term><varname>S</varname></term> |
| <term><varname>1</varname></term> |
| <term><varname>2</varname></term> |
| <term><varname>3</varname></term> |
| <term><varname>4</varname></term> |
| <term><varname>5</varname></term> |
| <listitem> |
| <para>Parameters understood by the system and service |
| manager, as compatibility and convenience options. For details, see |
| <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>locale.LANG=</varname></term> |
| <term><varname>locale.LANGUAGE=</varname></term> |
| <term><varname>locale.LC_CTYPE=</varname></term> |
| <term><varname>locale.LC_NUMERIC=</varname></term> |
| <term><varname>locale.LC_TIME=</varname></term> |
| <term><varname>locale.LC_COLLATE=</varname></term> |
| <term><varname>locale.LC_MONETARY=</varname></term> |
| <term><varname>locale.LC_MESSAGES=</varname></term> |
| <term><varname>locale.LC_PAPER=</varname></term> |
| <term><varname>locale.LC_NAME=</varname></term> |
| <term><varname>locale.LC_ADDRESS=</varname></term> |
| <term><varname>locale.LC_TELEPHONE=</varname></term> |
| <term><varname>locale.LC_MEASUREMENT=</varname></term> |
| <term><varname>locale.LC_IDENTIFICATION=</varname></term> |
| <listitem> |
| <para>Parameters understood by the system and service |
| manager to control locale and language settings. For |
| details, see |
| <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>fsck.mode=</varname></term> |
| <term><varname>fsck.repair=</varname></term> |
| |
| <listitem> |
| <para>Parameters understood by the file system checker |
| services. For details, see |
| <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>quotacheck.mode=</varname></term> |
| |
| <listitem> |
| <para>Parameter understood by the file quota checker |
| service. For details, see |
| <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.journald.forward_to_syslog=</varname></term> |
| <term><varname>systemd.journald.forward_to_kmsg=</varname></term> |
| <term><varname>systemd.journald.forward_to_console=</varname></term> |
| <term><varname>systemd.journald.forward_to_wall=</varname></term> |
| |
| <listitem> |
| <para>Parameters understood by the journal service. For |
| details, see |
| <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>vconsole.keymap=</varname></term> |
| <term><varname>vconsole.keymap_toggle=</varname></term> |
| <term><varname>vconsole.font=</varname></term> |
| <term><varname>vconsole.font_map=</varname></term> |
| <term><varname>vconsole.font_unimap=</varname></term> |
| |
| <listitem> |
| <para>Parameters understood by the virtual console setup logic. For details, see |
| <citerefentry><refentrytitle>vconsole.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>udev.log_priority=</varname></term> |
| <term><varname>rd.udev.log_priority=</varname></term> |
| <term><varname>udev.children_max=</varname></term> |
| <term><varname>rd.udev.children_max=</varname></term> |
| <term><varname>udev.exec_delay=</varname></term> |
| <term><varname>rd.udev.exec_delay=</varname></term> |
| <term><varname>udev.event_timeout=</varname></term> |
| <term><varname>rd.udev.event_timeout=</varname></term> |
| <term><varname>net.ifnames=</varname></term> |
| <term><varname>net.naming-scheme=</varname></term> |
| |
| <listitem> |
| <para>Parameters understood by the device event managing |
| daemon. For details, see |
| <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>plymouth.enable=</varname></term> |
| |
| <listitem> |
| <para>May be used to disable the Plymouth boot splash. For |
| details, see |
| <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>luks=</varname></term> |
| <term><varname>rd.luks=</varname></term> |
| <term><varname>luks.crypttab=</varname></term> |
| <term><varname>rd.luks.crypttab=</varname></term> |
| <term><varname>luks.name=</varname></term> |
| <term><varname>rd.luks.name=</varname></term> |
| <term><varname>luks.uuid=</varname></term> |
| <term><varname>rd.luks.uuid=</varname></term> |
| <term><varname>luks.options=</varname></term> |
| <term><varname>rd.luks.options=</varname></term> |
| <term><varname>luks.key=</varname></term> |
| <term><varname>rd.luks.key=</varname></term> |
| |
| <listitem> |
| <para>Configures the LUKS full-disk encryption logic at |
| boot. For details, see |
| <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>fstab=</varname></term> |
| <term><varname>rd.fstab=</varname></term> |
| |
| <listitem> |
| <para>Configures the <filename>/etc/fstab</filename> logic |
| at boot. For details, see |
| <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>root=</varname></term> |
| <term><varname>rootfstype=</varname></term> |
| <term><varname>rootflags=</varname></term> |
| <term><varname>ro</varname></term> |
| <term><varname>rw</varname></term> |
| |
| <listitem> |
| <para>Configures the root file system and its file system |
| type and mount options, as well as whether it shall be |
| mounted read-only or read-write initially. For details, |
| see |
| <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>mount.usr=</varname></term> |
| <term><varname>mount.usrfstype=</varname></term> |
| <term><varname>mount.usrflags=</varname></term> |
| |
| <listitem> |
| <para>Configures the /usr file system (if required) and |
| its file system type and mount options. For details, see |
| <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>roothash=</varname></term> |
| <term><varname>systemd.verity=</varname></term> |
| <term><varname>rd.systemd.verity=</varname></term> |
| <term><varname>systemd.verity_root_data=</varname></term> |
| <term><varname>systemd.verity_root_hash=</varname></term> |
| <listitem> |
| <para>Configures the integrity protection root hash for the root file system, and other related |
| parameters. For details, see |
| <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.gpt_auto=</varname></term> |
| <term><varname>rd.systemd.gpt_auto=</varname></term> |
| |
| <listitem> |
| <para>Configures whether GPT based partition auto-discovery |
| shall be attempted. For details, see |
| <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.default_timeout_start_sec=</varname></term> |
| |
| <listitem> |
| <para>Overwrites the default start job timeout <varname>DefaultTimeoutStartSec=</varname> at boot. For details, |
| see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.watchdog_device=</varname></term> |
| |
| <listitem> |
| <para>Overwrites the watchdog device path <varname>WatchdogDevice=</varname>. For details, see |
| <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.cpu_affinity=</varname></term> |
| |
| <listitem> |
| <para>Overrides the CPU affinity mask for the service manager and the default for all child |
| processes it forks. This takes precedence over <varname>CPUAffinity=</varname>, see |
| <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> |
| for details.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>modules_load=</varname></term> |
| <term><varname>rd.modules_load=</varname></term> |
| |
| <listitem> |
| <para>Load a specific kernel module early at boot. For |
| details, see |
| <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>resume=</varname></term> |
| <term><varname>resumeflags=</varname></term> |
| |
| <listitem> |
| <para>Enables resume from hibernation using the specified |
| device and mount options. All |
| <citerefentry project='man-pages'><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>-like |
| paths are supported. For details, see |
| <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>.</para> |
| </listitem> |
| </varlistentry> |
| |
| <varlistentry> |
| <term><varname>systemd.firstboot=</varname></term> |
| |
| <listitem><para>Takes a boolean argument, defaults to on. If off, |
| <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry> |
| will not query the user for basic system settings, even if the system boots up for the first time and the |
| relevant settings are not initialized yet.</para></listitem> |
| </varlistentry> |
| </variablelist> |
| |
| </refsect1> |
| |
| <refsect1> |
| <title>See Also</title> |
| <para> |
| <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, |
| <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
| <citerefentry project='man-pages'><refentrytitle>dracut.cmdline</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-debug-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-fsck@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-quotacheck.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-udevd.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry project='die-net'><refentrytitle>plymouth</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-cryptsetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-veritysetup-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-volatile-root.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-modules-load.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-backlight@.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-rfkill.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-hibernate-resume-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>systemd-firstboot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>, |
| <citerefentry><refentrytitle>bootctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> |
| </para> |
| </refsect1> |
| |
| </refentry> |