path: root/man/systemctl.xml

<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<!--
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->

<refentry id="systemctl">

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

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

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

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

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

        <refsect1>
                <title>Description</title>

                <para><command>systemctl</command> may be used to
                introspect and control the state of the
                <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                system and service manager.</para>
        </refsect1>

        <refsect1>
                <title>Options</title>

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

                <variablelist>
                        <varlistentry>
                                <term><option>--help</option></term>
                                <term><option>-h</option></term>

                                <listitem><para>Prints a short help
                                text and exits.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--version</option></term>

                                <listitem><para>Prints a short version
                                string and exits.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>When listing units,
                                limit display to certain unit
                                types. If not specified units of all
                                types will be shown. The argument
                                should be a unit type name such as
                                <option>service</option>,
                                <option>socket</option> and
                                similar.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>When showing
                                unit/job/manager properties, limit
                                display to certain properties as
                                specified as argument. If not
                                specified all set properties are
                                shown. The argument should be a
                                property name, such as
                                <literal>MainPID</literal>. If
                                specified more than once all
                                properties with the specified names
                                are shown.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>When listing units,
                                show all units, regardless of their
                                state, including inactive units. When
                                showing unit/job/manager properties,
                                show all properties regardless whether
                                they are set or not.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>When listing units,
                                show only failed units. Do not confuse
                                with
                                <option>--fail</option>.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Do not ellipsize unit
                                names and truncate unit descriptions
                                in the output of
                                <command>list-units</command> and
                                <command>list-jobs</command>.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>If the requested
                                operation conflicts with a pending
                                unfinished job, fail the command. If
                                this is not specified the requested
                                operation will replace the pending job,
                                if necessary. Do not confuse
                                with
                                <option>--failed</option>.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>When enqueuing a new
                                job ignore all its dependencies and
                                execute it immediately. If passed no
                                required units of the unit passed will
                                be pulled in, and no ordering
                                dependencies will be honoured. This is
                                mostly a debugging and rescue tool for
                                the administrator and should not be
                                used by
                                applications.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Suppress output to
                                STDOUT in
                                <command>snapshot</command>,
                                <command>is-active</command>,
                                <command>enable</command> and
                                <command>disable</command>.</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 it is completed. By passing this
                                argument it is only verified and
                                enqueued.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Do not print a legend, i.e.
                                the column headers and the footer with hints.
                                </para></listitem>
                        </varlistentry>

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

                                <listitem><para>Do not pipe output into a
                                pager.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--system</option></term>

                                <listitem><para>Talk to the systemd
                                system manager. (Default)</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--user</option></term>

                                <listitem><para>Talk to the systemd
                                manager of the calling user.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--order</option></term>
                                <term><option>--require</option></term>

                                <listitem><para>When used in
                                conjunction with the
                                <command>dot</command> command (see
                                below), selects which dependencies are
                                shown in the dependency graph. If
                                <option>--order</option> is passed
                                only dependencies of type
                                <varname>After=</varname> or
                                <varname>Before=</varname> are
                                shown. If <option>--require</option>
                                is passed only dependencies of type
                                <varname>Requires=</varname>,
                                <varname>RequiresOverridable=</varname>,
                                <varname>Requisite=</varname>,
                                <varname>RequisiteOverridable=</varname>,
                                <varname>Wants=</varname> and
                                <varname>Conflicts=</varname> are
                                shown. If neither is passed, shows
                                dependencies of all these
                                types.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Don't send wall
                                message before
                                halt, power-off, 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 kill. Must be one of
                                <option>main</option>,
                                <option>control</option> or
                                <option>all</option> to select whether
                                to kill only the main process of the
                                unit, the control process or all
                                processes of the unit. If omitted
                                defaults to
                                <option>all</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--signal=</option></term>
                                <term><option>-s</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
                                SIGTERM, SIGINT or SIGSTOP. If
                                omitted defaults to
                                <option>SIGTERM</option>.</para></listitem>
                        </varlistentry>

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

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

                                <listitem><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, they will
                                be executed immediately without
                                terminating any processes or umounting
                                any file systems. Warning: specifying
                                <option>--force</option> twice with
                                any of these operations might result
                                in data loss.</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 alternative
                                root path when looking for unit
                                files.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>When used with
                                <command>enable</command>/<command>disable</command>/<command>is-enabled</command> (and related commands), make
                                changes only temporarily, so that they
                                are dropped 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></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>-H</option></term>
                                <term><option>--host</option></term>

                                <listitem><para>Execute operation
                                remotely. Specify a hostname, or
                                username and hostname separated by @,
                                to connect to. This will use SSH to
                                talk to the remote systemd
                                instance.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>Acquire privileges via
                                PolicyKit before executing the
                                operation.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><option>--lines=</option></term>
                                <term><option>-n</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. Defaults to
                                10.</para></listitem>
                        </varlistentry>

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

                                <listitem><para>When used with
                                <command>status</command> continously
                                prints new journal entries as they are
                                appended to the
                                journal.</para></listitem>
                        </varlistentry>

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

                </variablelist>

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

                <variablelist>
                        <varlistentry>
                                <term><command>list-units</command></term>

                                <listitem><para>List known units.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>start [NAME...]</command></term>

                                <listitem><para>Start (activate) one
                                or more units specified on the command
                                line.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>stop [NAME...]</command></term>

                                <listitem><para>Stop (deactivate) one
                                or more units specified on the command
                                line.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>reload [NAME...]</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> or
                                <command>load</command>
                                commands.</para></listitem>

                        </varlistentry>
                        <varlistentry>
                                <term><command>restart [NAME...]</command></term>

                                <listitem><para>Restart one or more
                                units specified on the command
                                line. If the units are not running yet
                                they will be
                                started.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>try-restart [NAME...]</command></term>

                                <listitem><para>Restart one or more
                                units specified on the command
                                line if the units are running. Do
                                nothing if units are not running.
                                Note that for compatibility
                                with Red Hat init scripts
                                <command>condrestart</command> is
                                equivalent to this command.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>reload-or-restart [NAME...]</command></term>

                                <listitem><para>Reload one or more
                                units if they support it. If not,
                                restart them instead. If the units
                                are not running yet they will be
                                started.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>reload-or-try-restart [NAME...]</command></term>

                                <listitem><para>Reload one or more
                                units if they support it. If not,
                                restart them instead. Do nothing if
                                the units are not running. Note that
                                for compatibility with SysV init
                                scripts
                                <command>force-reload</command> is
                                equivalent to this
                                command.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>isolate [NAME]</command></term>

                                <listitem><para>Start the unit
                                specified on the command line and its
                                dependencies and stop all others.</para>

                                <para>This is similar to changing the
                                runlevel in a traditional init system. The
                                <command>isolate</command> command will
                                immediately stop processes that are not
                                enabled in the new unit, possibly including
                                the graphical environment or terminal you
                                are currently using.</para>

                                <para>Note that this works 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 [NAME...]</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>--kill-mode=</option> to
                                select the kill mode and
                                <option>--signal=</option> to select
                                the signal to send.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>is-active [NAME...]</command></term>

                                <listitem><para>Check whether any of
                                the specified units are active
                                (i.e. running). Returns an exit code
                                0 if at least one is active, non-zero
                                otherwise. Unless
                                <option>--quiet</option> is specified
                                this will also print the current unit
                                state to STDOUT.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>status [NAME...|PID...]</command></term>

                                <listitem><para>Show terse runtime
                                status information about one or more
                                units, followed by its most recent log
                                data from the journal. This function
                                is intended to generate human-readable
                                output. If you are looking for
                                computer-parsable output, use
                                <command>show</command> instead. If a
                                PID is passed information about the
                                unit the process of the PID belongs to
                                is shown.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>show [NAME...|JOB...]</command></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 is shown, and
                                if a job id is specified properties of
                                the job is 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></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>help [NAME...|PID...]</command></term>

                                <listitem><para>Show manual pages for
                                one or more units, if available. If a
                                PID is passed the manual pages for the
                                unit the process of the PID belongs to
                                is shown.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>reset-failed [NAME...]</command></term>

                                <listitem><para>Reset the
                                '<literal>failed</literal>' state of the
                                specified units, or if no unit name is
                                passed 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 restarted or
                                reset with this
                                command.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><command>list-unit-files</command></term>

                                <listitem><para>List installed unit files.
                                </para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><command>enable [NAME...]</command></term>

                                <listitem><para>Enable one or more
                                unit files, as specified on the
                                command line. This will create a
                                number of symlinks as encoded in the
                                <literal>[Install]</literal> sections
                                of the unit files. After the symlinks
                                have been created the systemd
                                configuration is reloaded (in a way
                                that is equivalent to
                                <command>daemon-reload</command>) to
                                ensure the changes are taken into
                                account immediately. Note that this
                                does not have the effect that any of
                                the units enabled are also started at
                                the same time. If this is desired a
                                separate <command>start</command>
                                command must be invoked for the
                                unit.</para>

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

                                <para>Note that this operation creates
                                only the suggested symlinks for the
                                units. 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 in the
                                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, to ensure his
                                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> or
                                <option>--global</option> is specified
                                this enables the unit for the system,
                                for the calling user only
                                or for all future logins of all
                                users. Note that in the latter case no
                                systemd daemon configuration is
                                reloaded.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><command>disable [NAME...]</command></term>

                                <listitem><para>Disables one or more
                                units. This removes all symlinks to
                                the specified unit files from the unit
                                configuration directory, and hence
                                undoes the changes made by
                                <command>enable</command>. Note
                                however that this removes
                                all symlinks to the unit files
                                (i.e. including manual additions), not
                                just those actually created by
                                <command>enable</command>. This call
                                implicitly reloads the systemd daemon
                                configuration after completing the
                                disabling of the units. Note that this
                                command does not implicitly stop the
                                units that is being disabled. If this
                                is desired an additional
                                <command>stop</command> command should
                                be executed afterwards.</para>

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

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

                        <varlistentry>
                                <term><command>is-enabled [NAME...]</command></term>

                                <listitem><para>Checks whether any of
                                the specified unit files is 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. To suppress
                                this output use
                                <option>--quiet</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><command>reenable [NAME...]</command></term>

                                <listitem><para>Reenable one or more
                                unit files, 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 is
                                enabled with to the defaults
                                configured in the
                                <literal>[Install]</literal> section
                                of the unit file.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><command>preset [NAME...]</command></term>

                                <listitem><para>Reset 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. For more information on preset
                                policy see
                                <citerefentry><refentrytitle>systemd.preset</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><command>mask [NAME...]</command></term>

                                <listitem><para>Mask one or more unit
                                files, as specified on the command
                                line. This will link these units 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 manual
                                activation. Use this option with
                                care.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><command>unmask [NAME...]</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>.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><command>link [NAME...]</command></term>

                                <listitem><para>Link a unit file that
                                is not in the unit file search paths
                                into the unit file search path. This
                                requires an absolute path to a unit
                                file. The effect of this can be undone
                                with <command>disable</command>. The
                                effect of this command is that a unit
                                file is available for
                                <command>start</command> and other
                                commands although it isn't installed
                                directly in the unit search
                                path.</para>
                                </listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><command>load [NAME...]</command></term>

                                <listitem><para>Load one or more units
                                specified on the command line. This
                                will simply load their configuration
                                from disk, but not start them. To
                                start them you need to use the
                                <command>start</command> command which
                                will implicitly load a unit that has
                                not been loaded yet. Note that systemd
                                garbage collects loaded units that are
                                not active or referenced by an active
                                unit. This means that units loaded
                                this way will usually not stay loaded
                                for long. Also note that this command
                                cannot be used to reload unit
                                configuration. Use the
                                <command>daemon-reload</command>
                                command for that. All in all, this
                                command is of little use except for
                                debugging.</para>
                                <para>This command should not be
                                confused with the
                                <command>daemon-reload</command> or
                                <command>reload</command>
                                commands.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>list-jobs</command></term>

                                <listitem><para>List jobs that are in progress.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>cancel [JOB...]</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>
                        <varlistentry>
                                <term><command>dump</command></term>

                                <listitem><para>Dump server
                                status. This will output a (usually
                                very long) human readable manager
                                status dump. Its format is subject to
                                change without notice and should not
                                be parsed by
                                applications.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>dot</command></term>

                                <listitem><para>Generate textual
                                dependency graph description in dot
                                format for further processing with the
                                GraphViz
                                <citerefentry><refentrytitle>dot</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                                tool. Use a command line like
                                <command>systemctl dot | dot -Tsvg >
                                systemd.svg</command> to generate a
                                graphical dependency tree. Unless
                                <option>--order</option> or
                                <option>--require</option> is passed
                                the generated graph will show both
                                ordering and requirement
                                dependencies.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>snapshot [NAME]</command></term>

                                <listitem><para>Create a snapshot. If
                                a snapshot name is specified, the new
                                snapshot will be named after it. If
                                none is specified an automatic
                                snapshot name is generated. In either
                                case, the snapshot name used is
                                printed to STDOUT, unless
                                <option>--quiet</option> is
                                specified.</para>

                                <para>A snapshot refers to a saved
                                state of the systemd manager. It is
                                implemented itself as a unit that is
                                generated dynamically with this
                                command and has dependencies on all
                                units active at the time. At a later
                                time the user may return to this state
                                by using the
                                <command>isolate</command> command on
                                the snapshot unit.</para></listitem>

                                <para>Snapshots are only useful for
                                saving and restoring which units are
                                running or are stopped, they do not
                                save/restore any other
                                state. Snapshots are dynamic and lost
                                on reboot.</para>
                        </varlistentry>
                        <varlistentry>
                                <term><command>delete [NAME...]</command></term>

                                <listitem><para>Remove a snapshot
                                previously created with
                                <command>snapshot</command>.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>daemon-reload</command></term>

                                <listitem><para>Reload systemd manager
                                configuration. This will reload all
                                unit files and recreate the entire
                                dependency tree. While the daemon is
                                reloaded, all sockets systemd listens
                                on on behalf of user configuration will
                                stay accessible.</para> <para>This
                                command should not be confused with
                                the <command>load</command> or
                                <command>reload</command>
                                commands.</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 reexecuted all sockets
                                systemd listens on on behalf of user
                                configuration will stay
                                accessible.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>show-environment</command></term>

                                <listitem><para>Dump the systemd
                                manager environment block. The
                                environment block will be dumped in
                                straight-forward form suitable for
                                sourcing into a shell script. This
                                environment block will be passed to
                                all processes the manager
                                spawns.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>set-environment [NAME=VALUE...]</command></term>

                                <listitem><para>Set one or more
                                systemd manager environment variables,
                                as specified on the command
                                line.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>unset-environment [NAME...]</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>default</command></term>

                                <listitem><para>Enter default
                                mode. This is mostly equivalent to
                                <command>start
                                default.target</command>.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>rescue</command></term>

                                <listitem><para>Enter rescue
                                mode. This is mostly equivalent to
                                <command>isolate
                                rescue.target</command> but also
                                prints a wall message to all
                                users.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>emergency</command></term>

                                <listitem><para>Enter emergency
                                mode. This is mostly equivalent to
                                <command>isolate
                                emergency.target</command> but also
                                prints a wall message to all
                                users.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>halt</command></term>

                                <listitem><para>Shut down and halt the
                                system. This is mostly equivalent to
                                <command>start halt.target</command>
                                but also prints a wall message to all
                                users.  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 the operation is immediately
                                executed without terminating any
                                processes or unmounting any file
                                systems. This may result in data
                                loss.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>poweroff</command></term>

                                <listitem><para>Shut down and
                                power-off the system. This is mostly
                                equivalent to <command>start
                                poweroff.target</command> but also
                                prints a wall message to all users. 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 the operation is
                                immediately executed without
                                terminating any processes or
                                unmounting any file systems. This may
                                result in data loss.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>reboot</command></term>

                                <listitem><para>Shut down and reboot
                                the system. This is mostly equivalent
                                to <command>start
                                reboot.target</command> but also
                                prints a wall message to all users. 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 the operation is immediately
                                executed without terminating any
                                processes or unmounting any file
                                systems. This may result in data
                                loss.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>kexec</command></term>

                                <listitem><para>Shut down and reboot
                                the system via kexec. This is mostly
                                equivalent to <command>start
                                kexec.target</command> but also prints
                                a wall message to all users. 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></term>

                                <listitem><para>Ask the systemd
                                manager to quit. This is only
                                supported for user service managers
                                (i.e. in conjunction with the
                                <option>--user</option> option) and
                                will fail otherwise.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>suspend</command></term>

                                <listitem><para>Suspend the system.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>hibernate</command></term>

                                <listitem><para>Hibernate the system.</para></listitem>
                        </varlistentry>
                        <varlistentry>
                                <term><command>switch-root [ROOT] [INIT]</command></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. Takes two arguments: the
                                directory to make the new root
                                directory, and the path to the new
                                system manager binary below it to
                                execute as PID 1. If the latter is
                                ommitted or the empty string, a
                                systemd binary will automatically be
                                searched for and used as init. If the
                                system manager path is ommitted or
                                equal the empty string 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.</para></listitem>
                        </varlistentry>
                </variablelist>

        </refsect1>

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

                <para>On success 0 is returned, a non-zero failure
                code otherwise.</para>
        </refsect1>

        <refsect1>
                <title>Environment</title>

                <variablelist>
                        <varlistentry>
                                <term><varname>$SYSTEMD_PAGER</varname></term>
                                <listitem><para>Pager to use when
                                <option>--no-pager</option> is not given;
                                overrides <varname>$PAGER</varname>.  Setting
                                this to an empty string or the value
                                <literal>cat</literal> is equivalent to passing
                                <option>--no-pager</option>.</para></listitem>
                        </varlistentry>
                </variablelist>
        </refsect1>

        <refsect1>
                <title>See Also</title>
                <para>
                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>loginctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.preset</refentrytitle><manvolnum>5</manvolnum></citerefentry>
                </para>
        </refsect1>

</refentry>