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<refentry id="kernel-command-line">

        <refentryinfo>
                <title>kernel-command-line</title>
                <productname>systemd</productname>

                <authorgroup>
                        <author>
                                <contrib>Developer</contrib>
                                <firstname>Lennart</firstname>
                                <surname>Poettering</surname>
                                <email>lennart@poettering.net</email>
                        </author>
                </authorgroup>
        </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.</para>

                <para>For command line parameters understood by the
                kernel, please see <ulink
                url="https://www.kernel.org/doc/Documentation/kernel-parameters.txt"><filename>kernel-parameters.txt</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='die-net'><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.crash_shell=</varname></term>
                                <term><varname>systemd.crash_chvt=</varname></term>
                                <term><varname>systemd.confirm_spawn=</varname></term>
                                <term><varname>systemd.show_status=</varname></term>
                                <term><varname>systemd.log_target=</varname></term>
                                <term><varname>systemd.log_level=</varname></term>
                                <term><varname>systemd.log_color=</varname></term>
                                <term><varname>systemd.log_location=</varname></term>
                                <term><varname>systemd.default_standard_output=</varname></term>
                                <term><varname>systemd.default_standard_error=</varname></term>
                                <term><varname>systemd.setenv=</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.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>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>emergency</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
                                        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>systemd-vconsole-setup.service</refentrytitle><manvolnum>8</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>

                                <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.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>rootfsflags=</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-writable initially. For
                                        details, see
                                        <citerefentry><refentrytitle>systemd-fstab-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>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>

                                <listitem>
                                        <para>Enables resume from hibernation
                                        using the specified device.
                                        All <citerefentry><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>
                </variablelist>

        </refsect1>

        <refsect1>
                  <title>See Also</title>
                  <para>
                          <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                          <citerefentry project='man-pages'><refentrytitle>bootparam</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                          <citerefentry project='die-net'><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-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                          <citerefentry><refentrytitle>systemd-gpt-auto-generator</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>
                  </para>
        </refsect1>

</refentry>
