systemctl: print a warning when trying to import a nonexistent variable

[thirdparty/systemd.git] / man / systemctl.xml

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<!-- SPDX-License-Identifier: LGPL-2.1-or-later -->

<refentry id="systemctl"
          xmlns:xi="http://www.w3.org/2001/XInclude">

  <refentryinfo>
    <title>systemctl</title>
    <productname>systemd</productname>
  </refentryinfo>

  <refmeta>
    <refentrytitle>systemctl</refentrytitle>
    <manvolnum>1</manvolnum>
  </refmeta>

  <refnamediv>
    <refname>systemctl</refname>
    <refpurpose>Control the systemd system and service manager</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <cmdsynopsis>
      <command>systemctl</command>
      <arg choice="opt" rep="repeat">OPTIONS</arg>
      <arg choice="plain">COMMAND</arg>
      <arg choice="opt" rep="repeat">UNIT</arg>
    </cmdsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Description</title>

    <para><command>systemctl</command> may be used to introspect and
    control the state of the <literal>systemd</literal> system and
    service manager. Please refer to
    <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
    for an introduction into the basic concepts and functionality this
    tool manages.</para>
  </refsect1>

  <refsect1>
    <title>Commands</title>

    <para>The following commands are understood:</para>

    <refsect2>
      <title>Unit Commands (Introspection and Modification)</title>

      <variablelist>
        <varlistentry>
          <term><command>list-units</command> <optional><replaceable>PATTERN</replaceable>…</optional></term>

          <listitem>
            <para>List units that <command>systemd</command> currently has in memory. This includes units that are
            either referenced directly or through a dependency, units that are pinned by applications programmatically,
            or units that were active in the past and have failed. By default only units which are active, have pending
            jobs, or have failed are shown; this can be changed with option <option>--all</option>. If one or more
            <replaceable>PATTERN</replaceable>s are specified, only units matching one of them are shown. The units
            that are shown are additionally filtered by <option>--type=</option> and <option>--state=</option> if those
            options are specified.</para>

            <para>Produces output similar to
            <programlisting>  UNIT                         LOAD   ACTIVE SUB     DESCRIPTION
  sys-module-fuse.device       loaded active plugged /sys/module/fuse
  -.mount                      loaded active mounted Root Mount
  boot-efi.mount               loaded active mounted /boot/efi
  systemd-journald.service     loaded active running Journal Service
  systemd-logind.service       loaded active running Login Service
● user@1000.service            loaded failed failed  User Manager for UID 1000
  …
  systemd-tmpfiles-clean.timer loaded active waiting Daily Cleanup of Temporary Directories

LOAD   = Reflects whether the unit definition was properly loaded.
ACTIVE = The high-level unit activation state, i.e. generalization of SUB.
SUB    = The low-level unit activation state, values depend on unit type.

123 loaded units listed. Pass --all to see loaded but inactive units, too.
To show all installed unit files use 'systemctl list-unit-files'.
            </programlisting>
            The header and the last unit of a given type are underlined if the
            terminal supports that. A colored dot is shown next to services which
            were masked, not found, or otherwise failed.</para>

            <para>The LOAD column shows the load state, one of <constant>loaded</constant>,
            <constant>not-found</constant>, <constant>bad-setting</constant>, <constant>error</constant>,
            <constant>masked</constant>. The ACTIVE columns shows the general unit state, one of
            <constant>active</constant>, <constant>reloading</constant>, <constant>inactive</constant>,
            <constant>failed</constant>, <constant>activating</constant>, <constant>deactivating</constant>. The SUB
            column shows the unit-type-specific detailed state of the unit, possible values vary by unit type. The list
            of possible LOAD, ACTIVE, and SUB states is not constant and new systemd releases may both add and remove
            values. <programlisting>systemctl --state=help</programlisting> command maybe be used to display the
            current set of possible values.</para>

            <para>This is the default command.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>list-sockets</command> <optional><replaceable>PATTERN</replaceable>…</optional></term>

          <listitem>
            <para>List socket units currently in memory, ordered by listening address.  If one or more
            <replaceable>PATTERN</replaceable>s are specified, only socket units matching one of them are
            shown. Produces output similar to
            <programlisting>
LISTEN           UNIT                        ACTIVATES
/dev/initctl     systemd-initctl.socket      systemd-initctl.service
…
[::]:22          sshd.socket                 sshd.service
kobject-uevent 1 systemd-udevd-kernel.socket systemd-udevd.service

5 sockets listed.</programlisting>
            Note: because the addresses might contains spaces, this output
            is not suitable for programmatic consumption.
            </para>

            <para>Also see <option>--show-types</option>, <option>--all</option>, and <option>--state=</option>.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>list-timers</command> <optional><replaceable>PATTERN</replaceable>…</optional></term>

          <listitem>
            <para>List timer units currently in memory, ordered by the time they elapse next. If one or more
            <replaceable>PATTERN</replaceable>s are specified, only units matching one of them are shown.
            Produces output similar to
            <programlisting>
NEXT                         LEFT          LAST                         PASSED     UNIT                         ACTIVATES
n/a                          n/a           Thu 2017-02-23 13:40:29 EST  3 days ago ureadahead-stop.timer        ureadahead-stop.service
Sun 2017-02-26 18:55:42 EST  1min 14s left Thu 2017-02-23 13:54:44 EST  3 days ago systemd-tmpfiles-clean.timer systemd-tmpfiles-clean.service
Sun 2017-02-26 20:37:16 EST  1h 42min left Sun 2017-02-26 11:56:36 EST  6h ago     apt-daily.timer              apt-daily.service
Sun 2017-02-26 20:57:49 EST  2h 3min left  Sun 2017-02-26 11:56:36 EST  6h ago     snapd.refresh.timer          snapd.refresh.service
            </programlisting>
            </para>

            <para><emphasis>NEXT</emphasis> shows the next time the timer will run.</para>
            <para><emphasis>LEFT</emphasis> shows how long till the next time the timer runs.</para>
            <para><emphasis>LAST</emphasis> shows the last time the timer ran.</para>
            <para><emphasis>PASSED</emphasis> shows how long has passed since the timer last ran.</para>
            <para><emphasis>UNIT</emphasis> shows the name of the timer</para>
            <para><emphasis>ACTIVATES</emphasis> shows the name the service the timer activates when it runs.</para>

            <para>Also see <option>--all</option> and <option>--state=</option>.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>is-active <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Check whether any of the specified units are active
            (i.e. running). Returns an exit code
            <constant>0</constant> if at least one is active, or
            non-zero otherwise. Unless <option>--quiet</option> is
            specified, this will also print the current unit state to
            standard output.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>is-failed <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Check whether any of the specified units are in a
            "failed" state. Returns an exit code
            <constant>0</constant> if at least one has failed,
            non-zero otherwise. Unless <option>--quiet</option> is
            specified, this will also print the current unit state to
            standard output.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>status</command> <optional><replaceable>PATTERN</replaceable>…|<replaceable>PID</replaceable>…]</optional></term>

          <listitem>
            <para>Show terse runtime status information about one or
            more units, followed by most recent log data from the
            journal. If no units are specified, show system status. If
            combined with <option>--all</option>, also show the status of
            all units (subject to limitations specified with
            <option>-t</option>). If a PID is passed, show information
            about the unit the process belongs to.</para>

            <para>This function is intended to generate human-readable
            output. If you are looking for computer-parsable output,
            use <command>show</command> instead. By default, this
            function only shows 10 lines of output and ellipsizes
            lines to fit in the terminal window. This can be changed
            with <option>--lines</option> and <option>--full</option>,
            see above. In addition, <command>journalctl
            --unit=<replaceable>NAME</replaceable></command> or
            <command>journalctl
            --user-unit=<replaceable>NAME</replaceable></command> use
            a similar filter for messages and might be more
            convenient.
            </para>

            <para>systemd implicitly loads units as necessary, so just running the <command>status</command> will
            attempt to load a file. The command is thus not useful for determining if something was already loaded or
            not.  The units may possibly also be quickly unloaded after the operation is completed if there's no reason
            to keep it in memory thereafter.
            </para>

            <example>
              <title>Example output from systemctl status </title>

              <programlisting>$ systemctl status bluetooth
● bluetooth.service - Bluetooth service
   Loaded: loaded (/usr/lib/systemd/system/bluetooth.service; enabled; vendor preset: enabled)
   Active: active (running) since Wed 2017-01-04 13:54:04 EST; 1 weeks 0 days ago
     Docs: man:bluetoothd(8)
 Main PID: 930 (bluetoothd)
   Status: "Running"
    Tasks: 1
   Memory: 648.0K
      CPU: 435ms
   CGroup: /system.slice/bluetooth.service
           └─930 /usr/lib/bluetooth/bluetoothd

Jan 12 10:46:45 example.com bluetoothd[8900]: Not enough free handles to register service
Jan 12 10:46:45 example.com bluetoothd[8900]: Current Time Service could not be registered
Jan 12 10:46:45 example.com bluetoothd[8900]: gatt-time-server: Input/output error (5)
</programlisting>

            <para>The dot ("●") uses color on supported terminals to summarize the unit state at a glance. White
            indicates an <literal>inactive</literal> or <literal>deactivating</literal> state. Red indicates a
            <literal>failed</literal> or <literal>error</literal> state and green indicates an
            <literal>active</literal>, <literal>reloading</literal> or <literal>activating</literal> state.
            </para>

            <para>The "Loaded:" line in the output will show <literal>loaded</literal> if the unit has been loaded into
            memory. Other possible values for "Loaded:" include: <literal>error</literal> if there was a problem
            loading it, <literal>not-found</literal> if no unit file was found for this unit,
            <literal>bad-setting</literal> if an essential unit file setting could not be parsed and
            <literal>masked</literal> if the unit file has been masked. Along with showing the path to the unit file,
            this line will also show the enablement state.  Enabled commands start at boot.  See the full table of
            possible enablement states — including the definition of <literal>masked</literal> — in the documentation
            for the <command>is-enabled</command> command.
            </para>

            <para>The "Active:" line shows active state.  The value is usually <literal>active</literal> or
            <literal>inactive</literal>. Active could mean started, bound, plugged in, etc depending on the unit type.
            The unit could also be in process of changing states, reporting a state of <literal>activating</literal> or
            <literal>deactivating</literal>. A special <literal>failed</literal> state is entered when the service
            failed in some way, such as a crash, exiting with an error code or timing out. If the failed state is
            entered the cause will be logged for later reference.</para>
            </example>

          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>show</command> <optional><replaceable>PATTERN</replaceable>…|<replaceable>JOB</replaceable>…</optional></term>

          <listitem>
            <para>Show properties of one or more units, jobs, or the manager itself. If no argument is specified,
            properties of the manager will be shown. If a unit name is specified, properties of the unit are shown, and
            if a job ID is specified, properties of the job are shown. By default, empty properties are suppressed. Use
            <option>--all</option> to show those too. To select specific properties to show, use
            <option>--property=</option>. This command is intended to be used whenever computer-parsable output is
            required. Use <command>status</command> if you are looking for formatted human-readable output.</para>

            <para>Many properties shown by <command>systemctl show</command> map directly to configuration settings of
            the system and service manager and its unit files. Note that the properties shown by the command are
            generally more low-level, normalized versions of the original configuration settings and expose runtime
            state in addition to configuration. For example, properties shown for service units include the service's
            current main process identifier as <literal>MainPID</literal> (which is runtime state), and time settings
            are always exposed as properties ending in the <literal>…USec</literal> suffix even if a matching
            configuration options end in <literal>…Sec</literal>, because microseconds is the normalized time unit used
            internally by the system and service manager.</para>

            <para>For details about many of these properties, see the documentation of the D-Bus interface
            backing these properties, see
            <citerefentry><refentrytitle>org.freedesktop.systemd1</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>cat <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Show backing files of one or more units. Prints the
            "fragment" and "drop-ins" (source files) of units. Each
            file is preceded by a comment which includes the file
            name. Note that this shows the contents of the backing files
            on disk, which may not match the system manager's
            understanding of these units if any unit files were
            updated on disk and the <command>daemon-reload</command>
            command wasn't issued since.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>help <replaceable>PATTERN</replaceable>…|<replaceable>PID</replaceable>…</command></term>

          <listitem>
            <para>Show manual pages for one or more units, if
            available. If a PID is given, the manual pages for the unit
            the process belongs to are shown.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>
            <command>list-dependencies</command>
            <optional><replaceable>UNIT</replaceable>...</optional>
          </term>

          <listitem>
            <para>Shows units required and wanted by the specified
            units. This recursively lists units following the
            <varname>Requires=</varname>,
            <varname>Requisite=</varname>,
            <varname>ConsistsOf=</varname>,
            <varname>Wants=</varname>, <varname>BindsTo=</varname>
            dependencies. If no units are specified,
            <filename>default.target</filename> is implied.</para>

            <para>By default, only target units are recursively
            expanded. When <option>--all</option> is passed, all other
            units are recursively expanded as well.</para>

            <para>Options <option>--reverse</option>,
            <option>--after</option>, <option>--before</option>
            may be used to change what types of dependencies
            are shown.</para>

            <para>Note that this command only lists units currently loaded into memory by the service manager. In
            particular, this command is not suitable to get a comprehensive list at all reverse dependencies on a
            specific unit, as it won't list the dependencies declared by units currently not loaded.</para>
          </listitem>
        </varlistentry>

        <!-- Commands that modify unit state start here -->

        <varlistentry>
          <term><command>start <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Start (activate) one or more units specified on the command line.</para>

            <para>Note that unit glob patterns expand to names of units currently in memory. Units which are
            not active and are not in a failed state usually are not in memory, and will not be matched by
            any pattern. In addition, in case of instantiated units, systemd is often unaware of the instance
            name until the instance has been started. Therefore, using glob patterns with
            <command>start</command> has limited usefulness. Also, secondary alias names of units are not
            considered.</para>

            <para>Option <option>--all</option> may be used to also operate on inactive units which are
            referenced by other loaded units. Note that this is not the same as operating on "all" possible
            units, because as the previous paragraph describes, such a list is ill-defined. Nevertheless,
            <command>systemctl start --all <replaceable>GLOB</replaceable></command> may be useful if all the
            units that should match the pattern are pulled in by some target which is known to be loaded.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>stop <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Stop (deactivate) one or more units specified on the command line.</para>

            <para>This command will fail if the unit does not exist or if stopping of the unit is prohibited (see
            <varname>RefuseManualStop=</varname> in
            <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
            It will <emphasis>not</emphasis> fail if any of the commands configured to stop the unit
            (<varname>ExecStop=</varname>, etc.) fail, because the manager will still forcibly terminate the
            unit.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>reload <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Asks all units listed on the command line to reload
            their configuration. Note that this will reload the
            service-specific configuration, not the unit configuration
            file of systemd. If you want systemd to reload the
            configuration file of a unit, use the
            <command>daemon-reload</command> command. In other words:
            for the example case of Apache, this will reload Apache's
            <filename>httpd.conf</filename> in the web server, not the
            <filename>apache.service</filename> systemd unit
            file.</para>

            <para>This command should not be confused with the
            <command>daemon-reload</command> command.</para>
          </listitem>

        </varlistentry>
        <varlistentry>
          <term><command>restart <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Stop and then start one or more units specified on the command line. If the units are not running
            yet, they will be started.</para>

            <para>Note that restarting a unit with this command does not necessarily flush out all of the unit's
            resources before it is started again. For example, the per-service file descriptor storage facility (see
            <varname>FileDescriptorStoreMax=</varname> in
            <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>) will
            remain intact as long as the unit has a job pending, and is only cleared when the unit is fully stopped and
            no jobs are pending anymore. If it is intended that the file descriptor store is flushed out, too, during a
            restart operation an explicit <command>systemctl stop</command> command followed by <command>systemctl
            start</command> should be issued.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>try-restart <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Stop and then start one or more units specified on the
            command line if the units are running. This does nothing
            if units are not running.</para>
            <!-- Note that we don't document condrestart here, as that is just compatibility support, and we generally
                 don't document that. -->
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>reload-or-restart <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Reload one or more units if they support it. If not, stop and then start them instead. If the units
            are not running yet, they will be started.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>try-reload-or-restart <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Reload one or more units if they support it. If not, stop and then start them instead. This does
            nothing if the units are not running.</para>
            <!-- Note that we don't document force-reload here, as that is just compatibility support, and we generally
                 don't document that. -->
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>isolate <replaceable>UNIT</replaceable></command></term>

          <listitem>
            <para>Start the unit specified on the command line and its dependencies
            and stop all others, unless they have
            <option>IgnoreOnIsolate=yes</option> (see
            <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
            If a unit name with no extension is given, an extension of
            <literal>.target</literal> will be assumed.</para>

            <para>This command is dangerous, since it will immediately stop processes that are not enabled in
            the new target, possibly including the graphical environment or terminal you are currently using.
            </para>

            <para>Note that this is allowed only on units where
            <option>AllowIsolate=</option> is enabled. See
            <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
            for details.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>kill <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Send a signal to one or more processes of the
            unit. Use <option>--kill-who=</option> to select which
            process to kill. Use <option>--signal=</option> to select
            the signal to send.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>clean <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Remove the configuration, state, cache, logs or runtime data of the specified units. Use
            <option>--what=</option> to select which kind of resource to remove. For service units this may
            be used to remove the directories configured with <varname>ConfigurationDirectory=</varname>,
            <varname>StateDirectory=</varname>, <varname>CacheDirectory=</varname>,
            <varname>LogsDirectory=</varname> and <varname>RuntimeDirectory=</varname>, see
            <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
            for details. For timer units this may be used to clear out the persistent timestamp data if
            <varname>Persistent=</varname> is used and <option>--what=state</option> is selected, see
            <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>. This
            command only applies to units that use either of these settings. If <option>--what=</option> is
            not specified, both the cache and runtime data are removed (as these two types of data are
            generally redundant and reproducible on the next invocation of the unit).</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>freeze <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Freeze one or more units specified on the
            command line using cgroup freezer</para>

            <para>Freezing the unit will cause all processes contained within the cgroup corresponding to the unit
            to be suspended. Being suspended means that unit's processes won't be scheduled to run on CPU until thawed.
            Note that this command is supported only on systems that use unified cgroup hierarchy. Unit is automatically
            thawed just before we execute a job against the unit, e.g. before the unit is stopped.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>thaw <replaceable>PATTERN</replaceable>…</command></term>

          <listitem>
            <para>Thaw (unfreeze) one or more units specified on the
            command line.</para>

            <para>This is the inverse operation to the <command>freeze</command> command and resumes the execution of
            processes in the unit's cgroup.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>set-property <replaceable>UNIT</replaceable> <replaceable>PROPERTY</replaceable>=<replaceable>VALUE</replaceable>…</command></term>

          <listitem>
            <para>Set the specified unit properties at runtime where
            this is supported. This allows changing configuration
            parameter properties such as resource control settings at
            runtime. Not all properties may be changed at runtime, but
            many resource control settings (primarily those in
            <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
            may. The changes are applied immediately, and stored on disk
            for future boots, unless <option>--runtime</option> is
            passed, in which case the settings only apply until the
            next reboot. The syntax of the property assignment follows
            closely the syntax of assignments in unit files.</para>

            <para>Example: <command>systemctl set-property foobar.service CPUWeight=200</command></para>

            <para>If the specified unit appears to be inactive, the
            changes will be only stored on disk as described
            previously hence they will be effective when the unit will
            be started.</para>

            <para>Note that this command allows changing multiple properties at the same time, which is
            preferable over setting them individually.</para>

            <para>Example: <command>systemctl set-property foobar.service CPUWeight=200 MemoryMax=2G IPAccounting=yes</command></para>

            <para>Like with unit file configuration settings, assigning an empty setting usually resets a
            property to its defaults.</para>

            <para>Example: <command>systemctl set-property avahi-daemon.service IPAddressDeny=</command></para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>bind</command> <replaceable>UNIT</replaceable> <replaceable>PATH</replaceable> [<replaceable>PATH</replaceable>]</term>

          <listitem><para>Bind mounts a file or directory from the host into the specified unit's view. The first path
          argument is the source file or directory on the host, the second path argument is the destination file or
          directory in the unit's view. When the latter is omitted, the destination path in the unit's view is the same as
          the source path on the host. When combined with the <option>--read-only</option> switch, a ready-only bind
          mount is created. When combined with the <option>--mkdir</option> switch, the destination path is first created
          before the mount is applied. Note that this option is currently only supported for units that run within a mount
          namespace (e.g.: with <option>RootImage=</option>, <option>PrivateMounts=</option>, etc.). This command supports bind
          mounting directories, regular files, device nodes, <constant>AF_UNIX</constant> socket nodes, as well as FIFOs.
          The bind mount is ephemeral, and it is undone as soon as the current unit process exists.
          Note that the namespace mentioned here, where the bind mount will be added to, is the one where the main service
          process runs, as other processes run in distinct namespaces (e.g.: <option>ExecReload=</option>,
          <option>ExecStartPre=</option>, etc.) </para></listitem>
        </varlistentry>

        <varlistentry>
          <term><command>service-log-level</command> <replaceable>SERVICE</replaceable> [<replaceable>LEVEL</replaceable>]</term>

          <listitem><para>If the <replaceable>LEVEL</replaceable> argument is not given, print the current
          log level as reported by service <replaceable>SERVICE</replaceable>.</para>

          <para>If the optional argument <replaceable>LEVEL</replaceable> is provided, then change the
          current log level of the service to <replaceable>LEVEL</replaceable>. The log level should be a
          typical syslog log level, i.e. a value in the range 0…7 or one of the strings
          <constant>emerg</constant>, <constant>alert</constant>, <constant>crit</constant>,
          <constant>err</constant>, <constant>warning</constant>, <constant>notice</constant>,
          <constant>info</constant>, <constant>debug</constant>; see <citerefentry
          project='man-pages'><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry>
          for details.</para>

          <para>The service must have the appropriate
          <varname>BusName=<replaceable>destination</replaceable></varname> property and also implement the
          generic
          <citerefentry><refentrytitle>org.freedesktop.LogControl1</refentrytitle><manvolnum>5</manvolnum></citerefentry>
          interface. (<filename>systemctl</filename> will use the generic D-Bus protocol to access the
          <interfacename>org.freedesktop.LogControl1.LogLevel</interfacename> interface for the D-Bus name
          <replaceable>destination</replaceable>.)</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><command>service-log-target</command> <replaceable>SERVICE</replaceable> [<replaceable>TARGET</replaceable>]</term>

          <listitem><para>If the <replaceable>TARGET</replaceable> argument is not given, print the current
          log target as reported by service <replaceable>SERVICE</replaceable>.</para>

          <para>If the optional argument <replaceable>TARGET</replaceable> is provided, then change the
          current log target of the service to <replaceable>TARGET</replaceable>. The log target should be
          one of the strings <constant>console</constant> (for log output to the service's standard error
          stream), <constant>kmsg</constant> (for log output to the kernel log buffer),
          <constant>journal</constant> (for log output to
          <citerefentry><refentrytitle>systemd-journald.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
          using the native journal protocol), <constant>syslog</constant> (for log output to the classic
          syslog socket <filename>/dev/log</filename>), <constant>null</constant> (for no log output
          whatsoever) or <constant>auto</constant> (for an automatically determined choice, typically
          equivalent to <constant>console</constant> if the service is invoked interactively, and
          <constant>journal</constant> or <constant>syslog</constant> otherwise).</para>

          <para>For most services, only a small subset of log targets make sense. In particular, most
          "normal" services should only implement <constant>console</constant>, <constant>journal</constant>,
          and <constant>null</constant>. Anything else is only appropriate for low-level services that
          are active in very early boot before proper logging is established.</para>

          <para>The service must have the appropriate
          <varname>BusName=<replaceable>destination</replaceable></varname> property and also implement the
          generic
          <citerefentry><refentrytitle>org.freedesktop.LogControl1</refentrytitle><manvolnum>5</manvolnum></citerefentry>
          interface. (<filename>systemctl</filename> will use the generic D-Bus protocol to access the
          <interfacename>org.freedesktop.LogControl1.LogLevel</interfacename> interface for the D-Bus name
          <replaceable>destination</replaceable>.)</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><command>reset-failed [<replaceable>PATTERN</replaceable>…]</command></term>

          <listitem>
            <para>Reset the <literal>failed</literal> state of the specified units, or if no unit name is passed, reset
            the state of all units. When a unit fails in some way (i.e. process exiting with non-zero error code,
            terminating abnormally or timing out), it will automatically enter the <literal>failed</literal> state and
            its exit code and status is recorded for introspection by the administrator until the service is
            stopped/re-started or reset with this command.</para>

            <para>In addition to resetting the <literal>failed</literal> state of a unit it also resets various other
            per-unit properties: the start rate limit counter of all unit types is reset to zero, as is the restart
            counter of service units. Thus, if a unit's start limit (as configured with
            <varname>StartLimitIntervalSec=</varname>/<varname>StartLimitBurst=</varname>) is hit and the unit refuses
            to be started again, use this command to make it startable again.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>Unit File Commands</title>

      <variablelist>
        <varlistentry>
          <term><command>list-unit-files</command> <optional><replaceable>PATTERN…</replaceable></optional></term>

          <listitem>
            <para>List unit files installed on the system, in combination with their enablement state (as reported by
            <command>is-enabled</command>). If one or more <replaceable>PATTERN</replaceable>s are specified, only unit
            files whose name matches one of them are shown (patterns matching unit file system paths are not
            supported).</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>enable <replaceable>UNIT</replaceable>…</command></term>
          <term><command>enable <replaceable>PATH</replaceable>…</command></term>

          <listitem>
            <para>Enable one or more units or unit instances. This will create a set of symlinks, as encoded in the
            [Install] sections of the indicated unit files. After the symlinks have been created,
            the system manager configuration is reloaded (in a way equivalent to <command>daemon-reload</command>), in
            order to ensure the changes are taken into account immediately. Note that this does
            <emphasis>not</emphasis> have the effect of also starting any of the units being enabled. If this is
            desired, combine this command with the <option>--now</option> switch, or invoke <command>start</command>
            with appropriate arguments later. Note that in case of unit instance enablement (i.e. enablement of units of
            the form <filename>foo@bar.service</filename>), symlinks named the same as instances are created in the
            unit configuration directory, however they point to the single template unit file they are instantiated
            from.</para>

            <para>This command expects either valid unit names (in which case various unit file directories are
            automatically searched for unit files with appropriate names), or absolute paths to unit files (in which
            case these files are read directly). If a specified unit file is located outside of the usual unit file
            directories, an additional symlink is created, linking it into the unit configuration path, thus ensuring
            it is found when requested by commands such as <command>start</command>. The file system where the linked
            unit files are located must be accessible when systemd is started (e.g. anything underneath
            <filename>/home/</filename> or <filename>/var/</filename> is not allowed, unless those directories are
            located on the root file system).</para>

            <para>This command will print the file system operations executed. This output may be suppressed by passing
            <option>--quiet</option>.
            </para>

            <para>Note that this operation creates only the symlinks suggested in the [Install]
            section of the unit files. While this command is the recommended way to manipulate the unit configuration
            directory, the administrator is free to make additional changes manually by placing or removing symlinks
            below this directory. This is particularly useful to create configurations that deviate from the suggested
            default installation. In this case, the administrator must make sure to invoke
            <command>daemon-reload</command> manually as necessary, in order to ensure the changes are taken into
            account.
            </para>

            <para>Enabling units should not be confused with starting (activating) units, as done by the
            <command>start</command> command. Enabling and starting units is orthogonal: units may be enabled without
            being started and started without being enabled. Enabling simply hooks the unit into various suggested
            places (for example, so that the unit is automatically started on boot or when a particular kind of
            hardware is plugged in). Starting actually spawns the daemon process (in case of service units), or binds
            the socket (in case of socket units), and so on.</para>

            <para>Depending on whether <option>--system</option>, <option>--user</option>, <option>--runtime</option>,
            or <option>--global</option> is specified, this enables the unit for the system, for the calling user only,
            for only this boot of the system, or for all future logins of all users.  Note that in the last case, no
            systemd daemon configuration is reloaded.</para>

            <para>Using <command>enable</command> on masked units is not supported and results in an error.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>disable <replaceable>UNIT</replaceable>…</command></term>

          <listitem>
            <para>Disables one or more units. This removes all symlinks to the unit files backing the specified units
            from the unit configuration directory, and hence undoes any changes made by <command>enable</command> or
            <command>link</command>. Note that this removes <emphasis>all</emphasis> symlinks to matching unit files,
            including manually created symlinks, and not just those actually created by <command>enable</command> or
            <command>link</command>. Note that while <command>disable</command> undoes the effect of
            <command>enable</command>, the two commands are otherwise not symmetric, as <command>disable</command> may
            remove more symlinks than a prior <command>enable</command> invocation of the same unit created.</para>

            <para>This command expects valid unit names only, it does not accept paths to unit files.</para>

            <para>In addition to the units specified as arguments, all units are disabled that are listed in the
            <varname>Also=</varname> setting contained in the [Install] section of any of the unit
            files being operated on.</para>

            <para>This command implicitly reloads the system manager configuration after completing the operation. Note
            that this command does not implicitly stop the units that are being disabled. If this is desired, either
            combine this command with the <option>--now</option> switch, or invoke the <command>stop</command> command
            with appropriate arguments later.</para>

            <para>This command will print information about the file system operations (symlink removals)
            executed. This output may be suppressed by passing <option>--quiet</option>.
            </para>

            <para>This command honors <option>--system</option>, <option>--user</option>, <option>--runtime</option>
            and <option>--global</option> in a similar way as <command>enable</command>.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>reenable <replaceable>UNIT</replaceable>…</command></term>

          <listitem>
            <para>Reenable one or more units, as specified on the command line. This is a combination of
            <command>disable</command> and <command>enable</command> and is useful to reset the symlinks a unit file is
            enabled with to the defaults configured in its [Install] section. This command expects
            a unit name only, it does not accept paths to unit files.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>preset <replaceable>UNIT</replaceable>…</command></term>

          <listitem>
            <para>Reset the enable/disable status one or more unit files, as specified on
            the command line, to the defaults configured in the preset policy files. This
            has the same effect as <command>disable</command> or
            <command>enable</command>, depending how the unit is listed in the preset
            files.</para>

            <para>Use <option>--preset-mode=</option> to control whether units shall be
            enabled and disabled, or only enabled, or only disabled.</para>

            <para>If the unit carries no install information, it will be silently ignored
            by this command. <replaceable>UNIT</replaceable> must be the real unit name,
            any alias names are ignored silently.</para>

            <para>For more information on the preset policy format, see
            <citerefentry><refentrytitle>systemd.preset</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
            For more information on the concept of presets, please consult the
            <ulink url="https://www.freedesktop.org/wiki/Software/systemd/Preset">Preset</ulink>
            document.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>preset-all</command></term>

          <listitem>
            <para>Resets all installed unit files to the defaults
            configured in the preset policy file (see above).</para>

            <para>Use <option>--preset-mode=</option> to control
            whether units shall be enabled and disabled, or only
            enabled, or only disabled.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>is-enabled <replaceable>UNIT</replaceable>…</command></term>

          <listitem>
            <para>Checks whether any of the specified unit files are
            enabled (as with <command>enable</command>). Returns an
            exit code of 0 if at least one is enabled, non-zero
            otherwise. Prints the current enable status (see table).
            To suppress this output, use <option>--quiet</option>.
            To show installation targets, use <option>--full</option>.
            </para>

            <table>
              <title>
                <command>is-enabled</command> output
              </title>

              <tgroup cols='3'>
                <thead>
                  <row>
                    <entry>Name</entry>
                    <entry>Description</entry>
                    <entry>Exit Code</entry>
                  </row>
                </thead>
                <tbody>
                  <row>
                    <entry><literal>enabled</literal></entry>
                    <entry morerows='1'>Enabled via <filename>.wants/</filename>, <filename>.requires/</filename> or <varname>Alias=</varname> symlinks (permanently in <filename>/etc/systemd/system/</filename>, or transiently in <filename>/run/systemd/system/</filename>).</entry>
                    <entry morerows='1'>0</entry>
                  </row>
                  <row>
                    <entry><literal>enabled-runtime</literal></entry>
                  </row>
                  <row>
                    <entry><literal>linked</literal></entry>
                    <entry morerows='1'>Made available through one or more symlinks to the unit file (permanently in <filename>/etc/systemd/system/</filename> or transiently in <filename>/run/systemd/system/</filename>), even though the unit file might reside outside of the unit file search path.</entry>
                    <entry morerows='1'>&gt; 0</entry>
                  </row>
                  <row>
                    <entry><literal>linked-runtime</literal></entry>
                  </row>
                  <row>
                    <entry><literal>alias</literal></entry>
                    <entry>The name is an alias (symlink to another unit file).</entry>
                    <entry>0</entry>
                  </row>
                  <row>
                    <entry><literal>masked</literal></entry>
                    <entry morerows='1'>Completely disabled, so that any start operation on it fails (permanently in <filename>/etc/systemd/system/</filename> or transiently in <filename>/run/systemd/systemd/</filename>).</entry>
                    <entry morerows='1'>&gt; 0</entry>
                  </row>
                  <row>
                    <entry><literal>masked-runtime</literal></entry>
                  </row>
                  <row>
                    <entry><literal>static</literal></entry>
                    <entry>The unit file is not enabled, and has no provisions for enabling in the [Install] unit file section.</entry>
                    <entry>0</entry>
                  </row>
                  <row>
                    <entry><literal>indirect</literal></entry>
                    <entry>The unit file itself is not enabled, but it has a non-empty <varname>Also=</varname> setting in the [Install] unit file section, listing other unit files that might be enabled, or it has an alias under a different name through a symlink that is not specified in <varname>Also=</varname>. For template unit files, an instance different than the one specified in <varname>DefaultInstance=</varname> is enabled.</entry>
                    <entry>0</entry>
                  </row>
                  <row>
                    <entry><literal>disabled</literal></entry>
                    <entry>The unit file is not enabled, but contains an [Install] section with installation instructions.</entry>
                    <entry>&gt; 0</entry>
                  </row>
                  <row>
                    <entry><literal>generated</literal></entry>
                    <entry>The unit file was generated dynamically via a generator tool. See <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>. Generated unit files may not be enabled, they are enabled implicitly by their generator.</entry>
                    <entry>0</entry>
                  </row>
                  <row>
                    <entry><literal>transient</literal></entry>
                    <entry>The unit file has been created dynamically with the runtime API. Transient units may not be enabled.</entry>
                    <entry>0</entry>
                  </row>
                  <row>
                    <entry><literal>bad</literal></entry>
                    <entry>The unit file is invalid or another error occurred. Note that <command>is-enabled</command> will not actually return this state, but print an error message instead. However the unit file listing printed by <command>list-unit-files</command> might show it.</entry>
                    <entry>&gt; 0</entry>
                  </row>
                </tbody>
              </tgroup>
            </table>

          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>mask <replaceable>UNIT</replaceable>…</command></term>

          <listitem>
            <para>Mask one or more units, as specified on the command line. This will link these unit files to
            <filename>/dev/null</filename>, making it impossible to start them. This is a stronger version of
            <command>disable</command>, since it prohibits all kinds of activation of the unit, including enablement
            and manual activation. Use this option with care. This honors the <option>--runtime</option> option to only
            mask temporarily until the next reboot of the system. The <option>--now</option> option may be used to
            ensure that the units are also stopped. This command expects valid unit names only, it does not accept unit
            file paths.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>unmask <replaceable>UNIT</replaceable>…</command></term>

          <listitem>
            <para>Unmask one or more unit files, as specified on the command line. This will undo the effect of
            <command>mask</command>. This command expects valid unit names only, it does not accept unit file
            paths.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>link <replaceable>PATH</replaceable>…</command></term>

          <listitem>
            <para>Link a unit file that is not in the unit file search paths into the unit file search path. This
            command expects an absolute path to a unit file. The effect of this may be undone with
            <command>disable</command>. The effect of this command is that a unit file is made available for commands
            such as <command>start</command>, even though it is not installed directly in the unit search path. The
            file system where the linked unit files are located must be accessible when systemd is started
            (e.g. anything underneath <filename>/home/</filename> or <filename>/var/</filename> is not allowed, unless
            those directories are located on the root file system).</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>revert <replaceable>UNIT</replaceable>…</command></term>

          <listitem>
            <para>Revert one or more unit files to their vendor versions. This command removes drop-in configuration
            files that modify the specified units, as well as any user-configured unit file that overrides a matching
            vendor supplied unit file. Specifically, for a unit <literal>foo.service</literal> the matching directories
            <literal>foo.service.d/</literal> with all their contained files are removed, both below the persistent and
            runtime configuration directories (i.e. below <filename>/etc/systemd/system</filename> and
            <filename>/run/systemd/system</filename>); if the unit file has a vendor-supplied version (i.e. a unit file
            located below <filename>/usr/</filename>) any matching persistent or runtime unit file that overrides it is
            removed, too. Note that if a unit file has no vendor-supplied version (i.e. is only defined below
            <filename>/etc/systemd/system</filename> or <filename>/run/systemd/system</filename>, but not in a unit
            file stored below <filename>/usr/</filename>), then it is not removed. Also, if a unit is masked, it is
            unmasked.</para>

            <para>Effectively, this command may be used to undo all changes made with <command>systemctl
            edit</command>, <command>systemctl set-property</command> and <command>systemctl mask</command> and puts
            the original unit file with its settings back in effect.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>add-wants <replaceable>TARGET</replaceable>
          <replaceable>UNIT</replaceable>…</command></term>
          <term><command>add-requires <replaceable>TARGET</replaceable>
          <replaceable>UNIT</replaceable>…</command></term>

          <listitem>
            <para>Adds <literal>Wants=</literal> or <literal>Requires=</literal>
            dependencies, respectively, to the specified
            <replaceable>TARGET</replaceable> for one or more units. </para>

            <para>This command honors <option>--system</option>,
            <option>--user</option>, <option>--runtime</option> and
            <option>--global</option> in a way similar to
            <command>enable</command>.</para>

          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>edit <replaceable>UNIT</replaceable>…</command></term>

          <listitem>
            <para>Edit a drop-in snippet or a whole replacement file if
            <option>--full</option> is specified, to extend or override the
            specified unit.</para>

            <para>Depending on whether <option>--system</option> (the default),
            <option>--user</option>, or <option>--global</option> is specified,
            this command creates a drop-in file for each unit either for the system,
            for the calling user, or for all futures logins of all users. Then,
            the editor (see the "Environment" section below) is invoked on
            temporary files which will be written to the real location if the
            editor exits successfully.</para>

            <para>If <option>--full</option> is specified, this will copy the
            original units instead of creating drop-in files.</para>

            <para>If <option>--force</option> is specified and any units do
            not already exist, new unit files will be opened for editing.</para>

            <para>If <option>--runtime</option> is specified, the changes will
            be made temporarily in <filename>/run/</filename> and they will be
            lost on the next reboot.</para>

            <para>If the temporary file is empty upon exit, the modification of
            the related unit is canceled.</para>

            <para>After the units have been edited, systemd configuration is
            reloaded (in a way that is equivalent to <command>daemon-reload</command>).
            </para>

            <para>Note that this command cannot be used to remotely edit units
            and that you cannot temporarily edit units which are in
            <filename>/etc/</filename>, since they take precedence over
            <filename>/run/</filename>.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>get-default</command></term>

          <listitem>
            <para>Return the default target to boot into. This returns
            the target unit name <filename>default.target</filename>
            is aliased (symlinked) to.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>set-default <replaceable>TARGET</replaceable></command></term>

          <listitem>
            <para>Set the default target to boot into. This sets
            (symlinks) the <filename>default.target</filename> alias
            to the given target unit.</para>
          </listitem>
        </varlistentry>

      </variablelist>
    </refsect2>

    <refsect2>
      <title>Machine Commands</title>

      <variablelist>
        <varlistentry>
          <term><command>list-machines</command> <optional><replaceable>PATTERN</replaceable>…</optional></term>

          <listitem>
            <para>List the host and all running local containers with
            their state. If one or more
            <replaceable>PATTERN</replaceable>s are specified, only
            containers matching one of them are shown.
            </para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>Job Commands</title>

      <variablelist>
        <varlistentry>
          <term><command>list-jobs <optional><replaceable>PATTERN…</replaceable></optional></command></term>

          <listitem>
            <para>List jobs that are in progress. If one or more
            <replaceable>PATTERN</replaceable>s are specified, only
            jobs for units matching one of them are shown.</para>

            <para>When combined with <option>--after</option> or <option>--before</option> the list is augmented with
            information on which other job each job is waiting for, and which other jobs are waiting for it, see
            above.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>cancel <replaceable>JOB</replaceable>…</command></term>

          <listitem>
            <para>Cancel one or more jobs specified on the command line
            by their numeric job IDs. If no job ID is specified, cancel
            all pending jobs.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>Environment Commands</title>

      <para><command>systemd</command> supports an environment block that is passed to processes the manager
      spawns. The names of the variables can contain ASCII letters, digits, and the underscore
      character. Variable names cannot be empty or start with a digit. In variable values, most characters
      are allowed, but non-printable characters are currently rejected. The total length of the environment
      block is limited to <constant>_SC_ARG_MAX</constant> value defined by
      <citerefentry project='man-pages'><refentrytitle>sysconf</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
      </para>

      <variablelist>
        <varlistentry>
          <term><command>show-environment</command></term>

          <listitem>
            <para>Dump the systemd manager environment block. This is the environment
            block that is passed to all processes the manager spawns. The environment
            block will be dumped in straight-forward form suitable for sourcing into
            most shells. If no special characters or whitespace is present in the variable
            values, no escaping is performed, and the assignments have the form
            <literal>VARIABLE=value</literal>. If whitespace or characters which have
            special meaning to the shell are present, dollar-single-quote escaping is
            used, and assignments have the form <literal>VARIABLE=$'value'</literal>.
            This syntax is known to be supported by
            <citerefentry project='die-net'><refentrytitle>bash</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
            <citerefentry project='die-net'><refentrytitle>zsh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
            <citerefentry project='die-net'><refentrytitle>ksh</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
            and
            <citerefentry project='die-net'><refentrytitle>busybox</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
            <citerefentry project='die-net'><refentrytitle>ash</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
            but not
            <citerefentry project='die-net'><refentrytitle>dash</refentrytitle><manvolnum>1</manvolnum></citerefentry>
            or
            <citerefentry project='die-net'><refentrytitle>fish</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
            </para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>set-environment <replaceable>VARIABLE=VALUE</replaceable>…</command></term>

          <listitem>
            <para>Set one or more systemd manager environment variables, as specified on the command
            line. This command will fail if variable names and values do not conform to the rules listed
            above.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>unset-environment <replaceable>VARIABLE</replaceable>…</command></term>

          <listitem>
            <para>Unset one or more systemd manager environment
            variables. If only a variable name is specified, it will be
            removed regardless of its value. If a variable and a value
            are specified, the variable is only removed if it has the
            specified value.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term>
            <command>import-environment</command>
            <replaceable>VARIABLE…</replaceable>
          </term>

          <listitem>
            <para>Import all, one or more environment variables set on the client into the systemd manager
            environment block. If a list of environment variable names is passed, client-side values are then
            imported into the manager's environment block. If any names are not valid environment variable
            names or have invalid values according to the rules described above, an error is raised. If no
            arguments are passed, the entire environment block inherited by the <command>systemctl</command>
            process is imported. In this mode, any inherited invalid environment variables are quietly
            ignored.</para>

            <para>Importing of the full inherited environment block (calling this command without any
            arguments) is deprecated. A shell will set dozens of variables which only make sense locally and
            are only meant for processes which are descendants of the shell. Such variables in the global
            environment block are confusing to other processes.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>Manager State Commands</title>

      <variablelist>
        <varlistentry>
          <term><command>daemon-reload</command></term>

          <listitem>
            <para>Reload the systemd manager configuration. This will
            rerun all generators (see
            <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>),
            reload all unit files, and recreate the entire dependency
            tree. While the daemon is being reloaded, all sockets
            systemd listens on behalf of user configuration will stay
            accessible.</para>

            <para>This command should not be confused with the
            <command>reload</command> command.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>daemon-reexec</command></term>

          <listitem>
            <para>Reexecute the systemd manager. This will serialize the
            manager state, reexecute the process and deserialize the
            state again. This command is of little use except for
            debugging and package upgrades. Sometimes, it might be
            helpful as a heavy-weight <command>daemon-reload</command>.
            While the daemon is being reexecuted, all sockets systemd listening
            on behalf of user configuration will stay accessible.
            </para>
          </listitem>
        </varlistentry>

        <varlistentry id='log-level'>
          <term><command>log-level</command> [<replaceable>LEVEL</replaceable>]</term>

          <listitem><para>If no argument is given, print the current log level of the manager. If an
          optional argument <replaceable>LEVEL</replaceable> is provided, then the command changes the
          current log level of the manager to <replaceable>LEVEL</replaceable> (accepts the same values as
          <option>--log-level=</option> described in
          <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>).
          </para></listitem>
        </varlistentry>

        <varlistentry>
          <term><command>log-target</command> [<replaceable>TARGET</replaceable>]</term>

          <listitem><para>If no argument is given, print the current log target of the manager. If an
          optional argument <replaceable>TARGET</replaceable> is provided, then the command changes the
          current log target of the manager to <replaceable>TARGET</replaceable> (accepts the same values as
          <option>--log-target=</option>, described in
          <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>).
          </para></listitem>
        </varlistentry>

        <varlistentry>
          <term><command>service-watchdogs</command> [yes|no]</term>

          <listitem><para>If no argument is given, print the current state of service runtime watchdogs of
          the manager. If an optional boolean argument is provided, then globally enables or disables the
          service runtime watchdogs (<option>WatchdogSec=</option>) and emergency actions (e.g.
          <option>OnFailure=</option> or <option>StartLimitAction=</option>); see
          <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
          The hardware watchdog is not affected by this setting.</para></listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>System Commands</title>

      <variablelist>
        <varlistentry>
          <term><command>is-system-running</command></term>

          <listitem>
            <para>Checks whether the system is operational. This
            returns success (exit code 0) when the system is fully up
            and running, specifically not in startup, shutdown or
            maintenance mode, and with no failed services. Failure is
            returned otherwise (exit code non-zero). In addition, the
            current state is printed in a short string to standard
            output, see the table below. Use <option>--quiet</option> to
            suppress this output.</para>

            <para>Use <option>--wait</option> to wait until the boot
            process is completed before printing the current state and
            returning the appropriate error status. If <option>--wait</option>
            is in use, states <varname>initializing</varname> or
            <varname>starting</varname> will not be reported, instead
            the command will block until a later state (such as
            <varname>running</varname> or <varname>degraded</varname>)
            is reached.</para>

            <table>
              <title><command>is-system-running</command> output</title>
              <tgroup cols='3'>
                <colspec colname='name'/>
                <colspec colname='description'/>
                <colspec colname='exit-code'/>
                <thead>
                  <row>
                    <entry>Name</entry>
                    <entry>Description</entry>
                    <entry>Exit Code</entry>
                  </row>
                </thead>
                <tbody>
                  <row>
                    <entry><varname>initializing</varname></entry>
                    <entry><para>Early bootup, before
                    <filename>basic.target</filename> is reached
                    or the <varname>maintenance</varname> state entered.
                    </para></entry>
                    <entry>&gt; 0</entry>
                  </row>
                  <row>
                    <entry><varname>starting</varname></entry>
                    <entry><para>Late bootup, before the job queue
                    becomes idle for the first time, or one of the
                    rescue targets are reached.</para></entry>
                    <entry>&gt; 0</entry>
                  </row>
                  <row>
                    <entry><varname>running</varname></entry>
                    <entry><para>The system is fully
                    operational.</para></entry>
                    <entry>0</entry>
                  </row>
                  <row>
                    <entry><varname>degraded</varname></entry>
                    <entry><para>The system is operational but one or more
                    units failed.</para></entry>
                    <entry>&gt; 0</entry>
                  </row>
                  <row>
                    <entry><varname>maintenance</varname></entry>
                    <entry><para>The rescue or emergency target is
                    active.</para></entry>
                    <entry>&gt; 0</entry>
                  </row>
                  <row>
                    <entry><varname>stopping</varname></entry>
                    <entry><para>The manager is shutting
                    down.</para></entry>
                    <entry>&gt; 0</entry>
                  </row>
                  <row>
                    <entry><varname>offline</varname></entry>
                    <entry><para>The manager is not
                    running. Specifically, this is the operational
                    state if an incompatible program is running as
                    system manager (PID 1).</para></entry>
                    <entry>&gt; 0</entry>
                  </row>
                  <row>
                    <entry><varname>unknown</varname></entry>
                    <entry><para>The operational state could not be
                    determined, due to lack of resources or another
                    error cause.</para></entry>
                    <entry>&gt; 0</entry>
                  </row>
                </tbody>
              </tgroup>
            </table>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>default</command></term>

          <listitem>
            <para>Enter default mode. This is equivalent to <command>systemctl isolate default.target</command>. This
            operation is blocking by default, use <option>--no-block</option> to request asynchronous behavior.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>rescue</command></term>

          <listitem>
            <para>Enter rescue mode. This is equivalent to <command>systemctl isolate rescue.target</command>. This
            operation is blocking by default, use <option>--no-block</option> to request asynchronous behavior.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>emergency</command></term>

          <listitem>
            <para>Enter emergency mode. This is equivalent to <command>systemctl isolate
            emergency.target</command>. This operation is blocking by default, use <option>--no-block</option> to
            request asynchronous behavior.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>halt</command></term>

          <listitem>
            <para>Shut down and halt the system. This is mostly equivalent to <command>systemctl start halt.target
            --job-mode=replace-irreversibly --no-block</command>, but also prints a wall message to all users. This command is
            asynchronous; it will return after the halt operation is enqueued, without waiting for it to complete. Note
            that this operation will simply halt the OS kernel after shutting down, leaving the hardware powered
            on. Use <command>systemctl poweroff</command> for powering off the system (see below).</para>

            <para>If combined with <option>--force</option>, shutdown of all running services is skipped, however all
            processes are killed and all file systems are unmounted or mounted read-only, immediately followed by the
            system halt.  If <option>--force</option> is specified twice, the operation is immediately executed without
            terminating any processes or unmounting any file systems. This may result in data loss. Note that when
            <option>--force</option> is specified twice the halt operation is executed by <command>systemctl</command>
            itself, and the system manager is not contacted. This means the command should succeed even when the system
            manager has crashed.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>poweroff</command></term>

          <listitem>
            <para>Shut down and power-off the system. This is mostly equivalent to <command>systemctl start
            poweroff.target --job-mode=replace-irreversibly --no-block</command>, but also prints a wall message to all
            users. This command is asynchronous; it will return after the power-off operation is enqueued, without
            waiting for it to complete.</para>

            <para>If combined with <option>--force</option>, shutdown of all running services is skipped, however all
            processes are killed and all file systems are unmounted or mounted read-only, immediately followed by the
            powering off. If <option>--force</option> is specified twice, the operation is immediately executed without
            terminating any processes or unmounting any file systems. This may result in data loss. Note that when
            <option>--force</option> is specified twice the power-off operation is executed by
            <command>systemctl</command> itself, and the system manager is not contacted. This means the command should
            succeed even when the system manager has crashed.</para>
          </listitem>
        </varlistentry>
        <varlistentry>
          <term><command>reboot</command></term>

          <listitem>
            <para>Shut down and reboot the system. This is mostly equivalent to <command>systemctl start reboot.target
            --job-mode=replace-irreversibly --no-block</command>, but also prints a wall message to all users. This
            command is asynchronous; it will return after the reboot operation is enqueued, without waiting for it to
            complete.</para>

            <para>If combined with <option>--force</option>, shutdown of all running services is skipped, however all
            processes are killed and all file systems are unmounted or mounted read-only, immediately followed by the
            reboot. If <option>--force</option> is specified twice, the operation is immediately executed without
            terminating any processes or unmounting any file systems. This may result in data loss. Note that when
            <option>--force</option> is specified twice the reboot operation is executed by
            <command>systemctl</command> itself, and the system manager is not contacted. This means the command should
            succeed even when the system manager has crashed.</para>

            <para>If the switch <option>--reboot-argument=</option> is given, it will be passed as the optional
            argument to the <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
            system call.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>kexec</command></term>

          <listitem>
            <para>Shut down and reboot the system via <command>kexec</command>. This is equivalent to
            <command>systemctl start kexec.target --job-mode=replace-irreversibly --no-block</command>. This command is
            asynchronous; it will return after the reboot operation is enqueued, without waiting for it to
            complete.</para>

            <para>If combined with <option>--force</option>, shutdown of all running services is skipped, however all
            processes are killed and all file systems are unmounted or mounted read-only, immediately followed by the
            reboot.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>exit</command> <optional><replaceable>EXIT_CODE</replaceable></optional></term>

          <listitem>
            <para>Ask the service manager to quit. This is only supported for user service managers (i.e. in
            conjunction with the <option>--user</option> option) or in containers and is equivalent to
            <command>poweroff</command> otherwise. This command is asynchronous; it will return after the exit
            operation is enqueued, without waiting for it to complete.</para>

            <para>The service manager will exit with the specified exit code, if
            <replaceable>EXIT_CODE</replaceable> is passed.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>switch-root</command> <replaceable>ROOT</replaceable> <optional><replaceable>INIT</replaceable></optional></term>

          <listitem>
            <para>Switches to a different root directory and executes a new system manager process below it. This is
            intended for usage in initial RAM disks ("initrd"), and will transition from the initrd's system manager
            process (a.k.a. "init" process) to the main system manager process which is loaded from the actual host
            volume. This call takes two arguments: the directory that is to become the new root directory, and the path
            to the new system manager binary below it to execute as PID 1. If the latter is omitted or the empty
            string, a systemd binary will automatically be searched for and used as init. If the system manager path is
            omitted, equal to the empty string or identical to the path to the systemd binary, the state of the
            initrd's system manager process is passed to the main system manager, which allows later introspection of
            the state of the services involved in the initrd boot phase.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>suspend</command></term>

          <listitem>
            <para>Suspend the system. This will trigger activation of the special target unit
            <filename>suspend.target</filename>. This command is asynchronous, and will return after the suspend
            operation is successfully enqueued. It will not wait for the suspend/resume cycle to complete.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>hibernate</command></term>

          <listitem>
            <para>Hibernate the system. This will trigger activation of the special target unit
            <filename>hibernate.target</filename>. This command is asynchronous, and will return after the hibernation
            operation is successfully enqueued. It will not wait for the hibernate/thaw cycle to complete.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>hybrid-sleep</command></term>

          <listitem>
            <para>Hibernate and suspend the system. This will trigger activation of the special target unit
            <filename>hybrid-sleep.target</filename>. This command is asynchronous, and will return after the hybrid
            sleep operation is successfully enqueued. It will not wait for the sleep/wake-up cycle to complete.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term><command>suspend-then-hibernate</command></term>

          <listitem>
            <para>Suspend the system and hibernate it after the delay specified in <filename>systemd-sleep.conf</filename>.
            This will trigger activation of the special target unit <filename>suspend-then-hibernate.target</filename>.
            This command is asynchronous, and will return after the hybrid sleep operation is successfully enqueued.
            It will not wait for the sleep/wake-up or hibernate/thaw cycle to complete.</para>
          </listitem>
        </varlistentry>
      </variablelist>
    </refsect2>

    <refsect2>
      <title>Parameter Syntax</title>

      <para>Unit commands listed above take either a single unit name (designated as <replaceable>UNIT</replaceable>),
      or multiple unit specifications (designated as <replaceable>PATTERN</replaceable>…). In the first case, the
      unit name with or without a suffix must be given. If the suffix is not specified (unit name is "abbreviated"),
      systemctl will append a suitable suffix, <literal>.service</literal> by default, and a type-specific suffix in
      case of commands which operate only on specific unit types. For example,
      <programlisting># systemctl start sshd</programlisting> and
      <programlisting># systemctl start sshd.service</programlisting>
      are equivalent, as are
      <programlisting># systemctl isolate default</programlisting>
      and
      <programlisting># systemctl isolate default.target</programlisting>
      Note that (absolute) paths to device nodes are automatically converted to device unit names, and other (absolute)
      paths to mount unit names.
      <programlisting># systemctl status /dev/sda
# systemctl status /home</programlisting>
      are equivalent to:
      <programlisting># systemctl status dev-sda.device
# systemctl status home.mount</programlisting>
      In the second case, shell-style globs will be matched against the primary names of all units currently in memory;
      literal unit names, with or without a suffix, will be treated as in the first case. This means that literal unit
      names always refer to exactly one unit, but globs may match zero units and this is not considered an
      error.</para>

      <para>Glob patterns use
      <citerefentry project='man-pages'><refentrytitle>fnmatch</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
      so normal shell-style globbing rules are used, and
      <literal>*</literal>, <literal>?</literal>,
      <literal>[]</literal> may be used. See
      <citerefentry project='man-pages'><refentrytitle>glob</refentrytitle><manvolnum>7</manvolnum></citerefentry>
      for more details. The patterns are matched against the primary names of
      units currently in memory, and patterns which do not match anything
      are silently skipped. For example:
      <programlisting># systemctl stop sshd@*.service</programlisting>
      will stop all <filename>sshd@.service</filename> instances. Note that alias names of units, and units that aren't
      in memory are not considered for glob expansion.
      </para>

      <para>For unit file commands, the specified <replaceable>UNIT</replaceable> should be the name of the unit file
      (possibly abbreviated, see above), or the absolute path to the unit file:
      <programlisting># systemctl enable foo.service</programlisting>
      or
      <programlisting># systemctl link /path/to/foo.service</programlisting>
      </para>
    </refsect2>

  </refsect1>

  <refsect1>
    <title>Options</title>

    <para>The following options are understood:</para>

    <variablelist>
      <varlistentry>
        <term><option>-t</option></term>
        <term><option>--type=</option></term>

        <listitem>
          <para>The argument should be a comma-separated list of unit
          types such as <option>service</option> and
          <option>socket</option>.
          </para>

          <para>If one of the arguments is a unit type, when listing
          units, limit display to certain unit types. Otherwise, units
          of all types will be shown.</para>

          <para>As a special case, if one of the arguments is
          <option>help</option>, a list of allowed values will be
          printed and the program will exit.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--state=</option></term>

        <listitem>
          <para>The argument should be a comma-separated list of unit
          LOAD, SUB, or ACTIVE states. When listing units, show only
          those in the specified states. Use <option>--state=failed</option>
          to show only failed units.</para>

          <para>As a special case, if one of the arguments is
          <option>help</option>, a list of allowed values will be
          printed and the program will exit.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-p</option></term>
        <term><option>--property=</option></term>

        <listitem>
          <para>When showing unit/job/manager properties with the
          <command>show</command> command, limit display to properties
          specified in the argument. The argument should be a
          comma-separated list of property names, such as
          <literal>MainPID</literal>. Unless specified, all known
          properties are shown. If specified more than once, all
          properties with the specified names are shown. Shell
          completion is implemented for property names.</para>

          <para>For the manager itself,
          <command>systemctl show</command> will show all available
          properties. Those properties are documented in
          <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
          </para>

          <para>Properties for units vary by unit type, so showing any
          unit (even a non-existent one) is a way to list properties
          pertaining to this type. Similarly, showing any job will list
          properties pertaining to all jobs. Properties for units are
          documented in
          <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
          and the pages for individual unit types
          <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
          <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
          etc.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-P</option></term>

        <listitem>
          <para>Equivalent to <option>--value</option> <option>--property=</option>, i.e. shows the
          value of the property without the property name or <literal>=</literal>. Note that using
          <option>-P</option> once will also affect all properties listed with
          <option>-p</option>/<option>--property=</option>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-a</option></term>
        <term><option>--all</option></term>

        <listitem>
          <para>When listing units with <command>list-units</command>, also show inactive units and
          units which are following other units. When showing unit/job/manager properties, show all
          properties regardless whether they are set or not.</para>

          <para>To list all units installed in the file system, use the
          <command>list-unit-files</command> command instead.</para>

          <para>When listing units with <command>list-dependencies</command>, recursively show
          dependencies of all dependent units (by default only dependencies of target units are
          shown).</para>

          <para>When used with <command>status</command>, show journal messages in full, even if they include
          unprintable characters or are very long. By default, fields with unprintable characters are
          abbreviated as "blob data". (Note that the pager may escape unprintable characters again.)</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-r</option></term>
        <term><option>--recursive</option></term>

        <listitem>
          <para>When listing units, also show units of local
          containers. Units of local containers will be prefixed with
          the container name, separated by a single colon character
          (<literal>:</literal>).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--reverse</option></term>

        <listitem>
          <para>Show reverse dependencies between units with
          <command>list-dependencies</command>, i.e. follow
          dependencies of type <varname>WantedBy=</varname>,
          <varname>RequiredBy=</varname>,
          <varname>PartOf=</varname>, <varname>BoundBy=</varname>,
          instead of <varname>Wants=</varname> and similar.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--after</option></term>

        <listitem>
          <para>With <command>list-dependencies</command>, show the
          units that are ordered before the specified unit. In other
          words, recursively list units following the
          <varname>After=</varname> dependency.</para>

          <para>Note that any <varname>After=</varname> dependency is
          automatically mirrored to create a
          <varname>Before=</varname> dependency. Temporal dependencies
          may be specified explicitly, but are also created implicitly
          for units which are <varname>WantedBy=</varname> targets
          (see
          <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>),
          and as a result of other directives (for example
          <varname>RequiresMountsFor=</varname>). Both explicitly
          and implicitly introduced dependencies are shown with
          <command>list-dependencies</command>.</para>

          <para>When passed to the <command>list-jobs</command> command, for each printed job show which other jobs are
          waiting for it. May be combined with <option>--before</option> to show both the jobs waiting for each job as
          well as all jobs each job is waiting for.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--before</option></term>

        <listitem>
          <para>With <command>list-dependencies</command>, show the
          units that are ordered after the specified unit. In other
          words, recursively list units following the
          <varname>Before=</varname> dependency.</para>

          <para>When passed to the <command>list-jobs</command> command, for each printed job show which other jobs it
          is waiting for. May be combined with <option>--after</option> to show both the jobs waiting for each job as
          well as all jobs each job is waiting for.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--with-dependencies</option></term>

        <listitem>
          <para>When used with <command>status</command>,
          <command>cat</command>, <command>list-units</command>, and
          <command>list-unit-files</command>, those commands print all
          specified units and the dependencies of those units.</para>

          <para>Options <option>--reverse</option>,
          <option>--after</option>, <option>--before</option>
          may be used to change what types of dependencies
          are shown.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-l</option></term>
        <term><option>--full</option></term>

        <listitem>
          <para>Do not ellipsize unit names, process tree entries,
          journal output, or truncate unit descriptions in the output
          of <command>status</command>, <command>list-units</command>,
          <command>list-jobs</command>, and
          <command>list-timers</command>.</para>
          <para>Also, show installation targets in the output of
          <command>is-enabled</command>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--value</option></term>

        <listitem>
          <para>When printing properties with <command>show</command>, only print the value, and skip the
          property name and <literal>=</literal>. Also see option <option>-P</option> above.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--show-types</option></term>

        <listitem>
          <para>When showing sockets, show the type of the socket.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--job-mode=</option></term>

        <listitem>
        <para>When queuing a new job, this option controls how to deal with
        already queued jobs. It takes one of <literal>fail</literal>,
        <literal>replace</literal>,
        <literal>replace-irreversibly</literal>,
        <literal>isolate</literal>,
        <literal>ignore-dependencies</literal>,
        <literal>ignore-requirements</literal>,
        <literal>flush</literal>, or
        <literal>triggering</literal>. Defaults to
        <literal>replace</literal>, except when the
        <command>isolate</command> command is used which implies the
        <literal>isolate</literal> job mode.</para>

        <para>If <literal>fail</literal> is specified and a requested
        operation conflicts with a pending job (more specifically:
        causes an already pending start job to be reversed into a stop
        job or vice versa), cause the operation to fail.</para>

        <para>If <literal>replace</literal> (the default) is
        specified, any conflicting pending job will be replaced, as
        necessary.</para>

        <para>If <literal>replace-irreversibly</literal> is specified,
        operate like <literal>replace</literal>, but also mark the new
        jobs as irreversible. This prevents future conflicting
        transactions from replacing these jobs (or even being enqueued
        while the irreversible jobs are still pending). Irreversible
        jobs can still be cancelled using the <command>cancel</command>
        command. This job mode should be used on any transaction which
        pulls in <filename>shutdown.target</filename>.</para>

        <para><literal>isolate</literal> is only valid for start
        operations and causes all other units to be stopped when the
        specified unit is started. This mode is always used when the
        <command>isolate</command> command is used.</para>

        <para><literal>flush</literal> will cause all queued jobs to
        be canceled when the new job is enqueued.</para>

        <para>If <literal>ignore-dependencies</literal> is specified,
        then all unit dependencies are ignored for this new job and
        the operation is executed immediately. If passed, no required
        units of the unit passed will be pulled in, and no ordering
        dependencies will be honored. This is mostly a debugging and
        rescue tool for the administrator and should not be used by
        applications.</para>

        <para><literal>ignore-requirements</literal> is similar to
        <literal>ignore-dependencies</literal>, but only causes the
        requirement dependencies to be ignored, the ordering
        dependencies will still be honored.</para>
        </listitem>

        <para><literal>triggering</literal> may only be used with
        <command>systemctl stop</command>. In this mode, the specified
        unit and any active units that trigger it are stopped. See the
        discussion of
        <varname>Triggers=</varname> in <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
        for more information about triggering units.</para>

      </varlistentry>

      <varlistentry>
        <term><option>-T</option></term>
        <term><option>--show-transaction</option></term>

        <listitem>
          <para>When enqueuing a unit job (for example as effect of a <command>systemctl start</command>
          invocation or similar), show brief information about all jobs enqueued, covering both the requested
          job and any added because of unit dependencies. Note that the output will only include jobs
          immediately part of the transaction requested. It is possible that service start-up program code
          run as effect of the enqueued jobs might request further jobs to be pulled in. This means that
          completion of the listed jobs might ultimately entail more jobs than the listed ones.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--fail</option></term>

        <listitem>
          <para>Shorthand for <option>--job-mode=</option>fail.</para>
          <para>When used with the <command>kill</command> command,
          if no units were killed, the operation results in an error.
          </para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--check-inhibitors=</option></term>

        <listitem>
          <para>When system shutdown or sleep state is request, this option controls how to deal with
          inhibitor locks. It takes one of <literal>auto</literal>, <literal>yes</literal> or
          <literal>no</literal>. Defaults to <literal>auto</literal>, which will behave like
          <literal>yes</literal> for interactive invocations (i.e. from a TTY) and <literal>no</literal>
          for non-interactive invocations.
          <literal>yes</literal> will let the request respect inhibitor locks.
          <literal>no</literal> will let the request ignore inhibitor locks.
          </para>
          <para>Applications can establish inhibitor locks to avoid that certain important operations
          (such as CD burning or suchlike) are interrupted by system shutdown or a sleep state. Any user may
          take these locks and privileged users may override these locks.
          If any locks are taken, shutdown and sleep state requests will normally fail (unless privileged)
          and a list of active locks is printed.
          However, if <literal>no</literal> is specified or <literal>auto</literal> is specified on a
          non-interactive requests, the established locks are ignored and not shown, and the operation
          attempted anyway, possibly requiring additional privileges.
          May be overridden by <option>--force</option>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-i</option></term>

        <listitem>
          <para>Shortcut for <option>--check-inhibitors=no</option>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--dry-run</option></term>

        <listitem>
          <para>Just print what would be done. Currently supported by verbs
          <command>halt</command>, <command>poweroff</command>, <command>reboot</command>,
          <command>kexec</command>, <command>suspend</command>, <command>hibernate</command>,
          <command>hybrid-sleep</command>, <command>suspend-then-hibernate</command>,
          <command>default</command>, <command>rescue</command>,
          <command>emergency</command>, and <command>exit</command>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-q</option></term>
        <term><option>--quiet</option></term>

        <listitem>
          <para>Suppress printing of the results of various commands
          and also the hints about truncated log lines. This does not
          suppress output of commands for which the printed output is
          the only result (like <command>show</command>). Errors are
          always printed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--no-block</option></term>

        <listitem>
          <para>Do not synchronously wait for the requested operation
          to finish. If this is not specified, the job will be
          verified, enqueued and <command>systemctl</command> will
          wait until the unit's start-up is completed. By passing this
          argument, it is only verified and enqueued. This option may not be
          combined with <option>--wait</option>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--wait</option></term>

        <listitem>
          <para>Synchronously wait for started units to terminate again.
          This option may not be combined with <option>--no-block</option>.
          Note that this will wait forever if any given unit never terminates
          (by itself or by getting stopped explicitly); particularly services
          which use <literal>RemainAfterExit=yes</literal>.</para>

          <para>When used with <command>is-system-running</command>, wait
          until the boot process is completed before returning.</para>
        </listitem>
      </varlistentry>

      <xi:include href="user-system-options.xml" xpointer="user" />
      <xi:include href="user-system-options.xml" xpointer="system" />

      <varlistentry>
        <term><option>--failed</option></term>

        <listitem>
          <para>List units in failed state. This is equivalent to
          <option>--state=failed</option>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--no-wall</option></term>

        <listitem>
          <para>Do not send wall message before halt, power-off and reboot.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--global</option></term>

        <listitem>
          <para>When used with <command>enable</command> and
          <command>disable</command>, operate on the global user
          configuration directory, thus enabling or disabling a unit
          file globally for all future logins of all users.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--no-reload</option></term>

        <listitem>
          <para>When used with <command>enable</command> and
          <command>disable</command>, do not implicitly reload daemon
          configuration after executing the changes.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--no-ask-password</option></term>

        <listitem>
          <para>When used with <command>start</command> and related
          commands, disables asking for passwords. Background services
          may require input of a password or passphrase string, for
          example to unlock system hard disks or cryptographic
          certificates. Unless this option is specified and the
          command is invoked from a terminal,
          <command>systemctl</command> will query the user on the
          terminal for the necessary secrets. Use this option to
          switch this behavior off. In this case, the password must be
          supplied by some other means (for example graphical password
          agents) or the service might fail. This also disables
          querying the user for authentication for privileged
          operations.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--kill-who=</option></term>

        <listitem>
          <para>When used with <command>kill</command>, choose which
          processes to send a signal to. Must be one of
          <option>main</option>, <option>control</option> or
          <option>all</option> to select whether to kill only the main
          process, the control process or all processes of the
          unit. The main process of the unit is the one that defines
          the life-time of it. A control process of a unit is one that
          is invoked by the manager to induce state changes of it. For
          example, all processes started due to the
          <varname>ExecStartPre=</varname>,
          <varname>ExecStop=</varname> or
          <varname>ExecReload=</varname> settings of service units are
          control processes. Note that there is only one control
          process per unit at a time, as only one state change is
          executed at a time. For services of type
          <varname>Type=forking</varname>, the initial process started
          by the manager for <varname>ExecStart=</varname> is a
          control process, while the process ultimately forked off by
          that one is then considered the main process of the unit (if
          it can be determined). This is different for service units
          of other types, where the process forked off by the manager
          for <varname>ExecStart=</varname> is always the main process
          itself. A service unit consists of zero or one main process,
          zero or one control process plus any number of additional
          processes. Not all unit types manage processes of these
          types however. For example, for mount units, control processes
          are defined (which are the invocations of
          <filename>&MOUNT_PATH;</filename> and
          <filename>&UMOUNT_PATH;</filename>), but no main process
          is defined. If omitted, defaults to
          <option>all</option>.</para>
        </listitem>

      </varlistentry>

      <varlistentry>
        <term><option>-s</option></term>
        <term><option>--signal=</option></term>

        <listitem>
          <para>When used with <command>kill</command>, choose which
          signal to send to selected processes. Must be one of the
          well-known signal specifiers such as <constant>SIGTERM</constant>, <constant>SIGINT</constant> or
          <constant>SIGSTOP</constant>. If omitted, defaults to
          <option>SIGTERM</option>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--what=</option></term>

        <listitem>
          <para>Select what type of per-unit resources to remove when the <command>clean</command> command is
          invoked, see below. Takes one of <constant>configuration</constant>, <constant>state</constant>,
          <constant>cache</constant>, <constant>logs</constant>, <constant>runtime</constant> to select the
          type of resource. This option may be specified more than once, in which case all specified resource
          types are removed. Also accepts the special value <constant>all</constant> as a shortcut for
          specifying all five resource types. If this option is not specified defaults to the combination of
          <constant>cache</constant> and <constant>runtime</constant>, i.e. the two kinds of resources that
          are generally considered to be redundant and can be reconstructed on next invocation.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-f</option></term>
        <term><option>--force</option></term>

        <listitem>
          <para>When used with <command>enable</command>, overwrite
          any existing conflicting symlinks.</para>

          <para>When used with <command>edit</command>, create all of the
          specified units which do not already exist.</para>

          <para>When used with <command>halt</command>, <command>poweroff</command>, <command>reboot</command> or
          <command>kexec</command>, execute the selected operation without shutting down all units. However, all
          processes will be killed forcibly and all file systems are unmounted or remounted read-only. This is hence a
          drastic but relatively safe option to request an immediate reboot. If <option>--force</option> is specified
          twice for these operations (with the exception of <command>kexec</command>), they will be executed
          immediately, without terminating any processes or unmounting any file systems. Warning: specifying
          <option>--force</option> twice with any of these operations might result in data loss. Note that when
          <option>--force</option> is specified twice the selected operation is executed by
          <command>systemctl</command> itself, and the system manager is not contacted. This means the command should
          succeed even when the system manager has crashed.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--message=</option></term>

        <listitem>
          <para>When used with <command>halt</command>, <command>poweroff</command> or <command>reboot</command>, set a
          short message explaining the reason for the operation. The message will be logged together with the default
          shutdown message.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--now</option></term>

        <listitem>
          <para>When used with <command>enable</command>, the units
          will also be started. When used with <command>disable</command> or
          <command>mask</command>, the units will also be stopped. The start
          or stop operation is only carried out when the respective enable or
          disable operation has been successful.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--root=</option></term>

        <listitem>
          <para>When used with
          <command>enable</command>/<command>disable</command>/<command>is-enabled</command>
          (and related commands), use the specified root path when looking for unit
          files. If this option is present, <command>systemctl</command> will operate on
          the file system directly, instead of communicating with the <command>systemd</command>
          daemon to carry out changes.</para>
        </listitem>

      </varlistentry>

      <varlistentry>
        <term><option>--runtime</option></term>

        <listitem>
          <para>When used with <command>enable</command>,
          <command>disable</command>, <command>edit</command>,
          (and related commands), make changes only temporarily, so
          that they are lost on the next reboot. This will have the
          effect that changes are not made in subdirectories of
          <filename>/etc/</filename> but in <filename>/run/</filename>,
          with identical immediate effects, however, since the latter
          is lost on reboot, the changes are lost too.</para>

          <para>Similarly, when used with
          <command>set-property</command>, make changes only
          temporarily, so that they are lost on the next
          reboot.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--preset-mode=</option></term>

        <listitem>
          <para>Takes one of <literal>full</literal> (the default),
          <literal>enable-only</literal>,
          <literal>disable-only</literal>. When used with the
          <command>preset</command> or <command>preset-all</command>
          commands, controls whether units shall be disabled and
          enabled according to the preset rules, or only enabled, or
          only disabled.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-n</option></term>
        <term><option>--lines=</option></term>

        <listitem>
          <para>When used with <command>status</command>, controls the number of journal lines to show, counting from
          the most recent ones. Takes a positive integer argument, or 0 to disable journal output. Defaults to
          10.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>-o</option></term>
        <term><option>--output=</option></term>

        <listitem>
          <para>When used with <command>status</command>, controls the
          formatting of the journal entries that are shown. For the
          available choices, see
          <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
          Defaults to <literal>short</literal>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--firmware-setup</option></term>

        <listitem>
          <para>When used with the <command>reboot</command> command, indicate to the system's firmware to reboot into
          the firmware setup interface. Note that this functionality is not available on all systems.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--boot-loader-menu=</option></term>

        <listitem>
          <para>When used with the <command>reboot</command> command, indicate to the system's boot loader to show the
          boot loader menu on the following boot. Takes a time value as parameter — indicating the menu timeout. Pass
          zero in order to disable the menu timeout. Note that not all boot loaders support this
          functionality.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--boot-loader-entry=</option></term>

        <listitem>
          <para>When used with the <command>reboot</command> command, indicate to the system's boot loader to boot into
          a specific boot loader entry on the following boot. Takes a boot loader entry identifier as argument, or
          <literal>help</literal> in order to list available entries. Note that not all boot loaders support this
          functionality.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--reboot-argument=</option></term>

        <listitem>
          <para>This switch is used with <command>reboot</command>. The value is architecture and firmware specific. As an example, <literal>recovery</literal>
            might be used to trigger system recovery, and <literal>fota</literal> might be used to trigger a
            <quote>firmware over the air</quote> update.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--plain</option></term>

        <listitem>
          <para>When used with <command>list-dependencies</command>,
          <command>list-units</command> or <command>list-machines</command>,
          the output is printed as a list instead of a tree, and the bullet
          circles are omitted.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--timestamp=</option></term>

        <listitem>
          <para>Takes one of <literal>pretty</literal> (the default),
          <literal>us</literal>, <literal>µs</literal>, <literal>utc</literal>.
          Changes the format of printed timestamps.
          <literal>pretty</literal>: <literal>Day YYYY-MM-DD HH:MM:SS TZ</literal>
          <literal>us</literal> or <literal>µs</literal>: <literal>Day YYYY-MM-DD HH:MM:SS.UUUUUU TZ</literal>
          <literal>utc</literal>: <literal>Day YYYY-MM-DD HH:MM:SS UTC</literal></para>
          <literal>us+utc</literal> or <literal>µs+utc</literal>: <literal>Day YYYY-MM-DD HH:MM:SS.UUUUUU UTC</literal>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--mkdir</option></term>

        <listitem><para>When used with <command>bind</command>, creates the destination file or directory before
        applying the bind mount. Note that even though the name of this option suggests that it is suitable only for
        directories, this option also creates the destination file node to mount over if the object to mount is not
        a directory, but a regular file, device node, socket or FIFO.</para></listitem>
      </varlistentry>

      <varlistentry>
        <term><option>--read-only</option></term>

        <listitem><para>When used with <command>bind</command>, creates a read-only bind mount.</para></listitem>
      </varlistentry>

      <xi:include href="user-system-options.xml" xpointer="host" />
      <xi:include href="user-system-options.xml" xpointer="machine" />

      <xi:include href="standard-options.xml" xpointer="no-pager" />
      <xi:include href="standard-options.xml" xpointer="no-legend" />
      <xi:include href="standard-options.xml" xpointer="help" />
      <xi:include href="standard-options.xml" xpointer="version" />
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Exit status</title>

    <para>On success, 0 is returned, a non-zero failure code otherwise.</para>

    <para><command>systemctl</command> uses the return codes defined by LSB, as defined in
    <ulink url="http://refspecs.linuxbase.org/LSB_3.0.0/LSB-PDA/LSB-PDA/iniscrptact.html">LSB 3.0.0</ulink>.
    </para>

    <table>
      <title>LSB return codes</title>

      <tgroup cols='3'>
        <thead>
          <row>
            <entry>Value</entry>
            <entry>Description in LSB</entry>
            <entry>Use in systemd</entry>
          </row>
        </thead>
        <tbody>
          <row>
            <entry><constant>0</constant></entry>
            <entry>"program is running or service is OK"</entry>
            <entry>unit is active</entry>
          </row>
          <row>
            <entry><constant>1</constant></entry>
            <entry>"program is dead and <filename>/var/run</filename> pid file exists"</entry>
            <entry>unit <emphasis>not</emphasis> failed (used by <command>is-failed</command>)</entry>
          </row>
          <row>
            <entry><constant>2</constant></entry>
            <entry>"program is dead and <filename>/var/lock</filename> lock file exists"</entry>
            <entry>unused</entry>
          </row>
          <row>
            <entry><constant>3</constant></entry>
            <entry>"program is not running"</entry>
            <entry>unit is not active</entry>
          </row>
          <row>
            <entry><constant>4</constant></entry>
            <entry>"program or service status is unknown"</entry>
            <entry>no such unit</entry>
          </row>
        </tbody>
      </tgroup>
    </table>

    <para>The mapping of LSB service states to systemd unit states is imperfect, so it is better to
    not rely on those return values but to look for specific unit states and substates instead.
    </para>
  </refsect1>

  <refsect1>
    <title>Environment</title>

    <variablelist class='environment-variables'>
      <varlistentry>
        <term><varname>$SYSTEMD_EDITOR</varname></term>

        <listitem><para>Editor to use when editing units; overrides
        <varname>$EDITOR</varname> and <varname>$VISUAL</varname>. If neither
        <varname>$SYSTEMD_EDITOR</varname> nor <varname>$EDITOR</varname> nor
        <varname>$VISUAL</varname> are present or if it is set to an empty
        string or if their execution failed, systemctl will try to execute well
        known editors in this order:
        <citerefentry project='die-net'><refentrytitle>editor</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
        <citerefentry project='die-net'><refentrytitle>nano</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
        <citerefentry project='die-net'><refentrytitle>vim</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
        <citerefentry project='die-net'><refentrytitle>vi</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
        </para></listitem>
      </varlistentry>
    </variablelist>
    <xi:include href="less-variables.xml" xpointer="pager"/>
    <xi:include href="less-variables.xml" xpointer="less"/>
    <xi:include href="less-variables.xml" xpointer="lesscharset"/>
    <xi:include href="less-variables.xml" xpointer="lesssecure"/>
    <xi:include href="less-variables.xml" xpointer="colors"/>
    <xi:include href="less-variables.xml" xpointer="urlify"/>
  </refsect1>

  <refsect1>
    <title>See Also</title>
    <para>
      <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>loginctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>machinectl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.preset</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
      <citerefentry><refentrytitle>systemd.generator</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
      <citerefentry project='man-pages'><refentrytitle>glob</refentrytitle><manvolnum>7</manvolnum></citerefentry>
    </para>
  </refsect1>

</refentry>