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2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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6 This file is part of systemd.
8 Copyright 2010 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
15 systemd is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public License
21 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24 <refentry id="systemctl">
27 <title>systemctl</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>systemctl</refentrytitle>
42 <manvolnum>1</manvolnum>
46 <refname>systemctl</refname>
47 <refpurpose>Control the systemd system and service manager</refpurpose>
52 <command>systemctl</command>
53 <arg choice="opt" rep="repeat">OPTIONS</arg>
54 <arg choice="plain">COMMAND</arg>
55 <arg choice="opt" rep="repeat">NAME</arg>
60 <title>Description</title>
62 <para><command>systemctl</command> may be used to
63 introspect and control the state of the
64 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
65 system and service manager.</para>
67 <para>For unit commands, the <replaceable>NAME</replaceable> represents full name of the unit.
69 systemctl start foo.service
71 For unit file commands, the <replaceable>NAME</replaceable> represents the full name of the unit file, or the absolute path to the unit file.
73 systemctl start /path/to/foo.service
75 While working with services/service files, <command>systemctl</command> implicitly appends the ".service" suffix when it is missing.
78 </programlisting></para>
82 <title>Options</title>
84 <para>The following options are understood:</para>
88 <term><option>-h</option></term>
89 <term><option>--help</option></term>
91 <listitem><para>Prints a short help
92 text and exits.</para></listitem>
96 <term><option>--version</option></term>
99 <para>Prints a short version string and exits.</para>
104 <term><option>-t</option></term>
105 <term><option>--type=</option></term>
108 <para>The argument should be a comma-separated list of unit
109 types such as <option>service</option> and
110 <option>socket</option>.
113 <para>If one of the arguments is a unit type, when listing
114 units, limit display to certain unit types. Otherwise, units
115 of all types will be shown.</para>
117 <para>As a special case, if one of the arguments is
118 <option>help</option>, a list of allowed values will be
119 printed and the program will exit.</para>
124 <term><option>--state=</option></term>
127 <para>The argument should be a comma-separated list of unit LOAD,
128 SUB, or ACTIVE states. When listing units, show only those
129 in specified states.</para>
134 <term><option>-p</option></term>
135 <term><option>--property=</option></term>
138 <para>When showing unit/job/manager properties with the
139 <command>show</command> command, limit display to certain
140 properties as specified as argument. If not specified, all
141 set properties are shown. The argument should be a
142 comma-separated list of property names, such as
143 <literal>MainPID</literal>. If specified more than once, all
144 properties with the specified names are shown.</para>
149 <term><option>-a</option></term>
150 <term><option>--all</option></term>
153 <para>When listing units, show all loaded units, regardless
154 of their state, including inactive units. When showing
155 unit/job/manager properties, show all properties regardless
156 whether they are set or not.</para>
157 <para>To list all units installed on the system, use the
158 <command>list-unit-files</command> command instead.</para>
163 <term><option>--reverse</option></term>
166 <para>Show reverse dependencies between units with
167 <command>list-dependencies</command>, i.e. units with
168 dependencies of type <varname>Wants=</varname> or
169 <varname>Requires=</varname> on the given unit.
175 <term><option>--after</option></term>
176 <term><option>--before</option></term>
179 <para>Show which units are started after or before
180 with <command>list-dependencies</command>, respectively.
186 <term><option>-l</option></term>
187 <term><option>--full</option></term>
190 <para>Do not ellipsize unit names, process tree entries, and
191 truncate unit descriptions in the output of
192 <command>list-units</command> and
193 <command>list-jobs</command>.</para>
198 <term><option>--fail</option></term>
201 <para>If the requested operation conflicts with a pending
202 unfinished job, fail the command. If this is not specified,
203 the requested operation will replace the pending job, if
204 necessary. Do not confuse with
205 <option>--failed</option>.</para>
210 <term><option>--show-types</option></term>
213 <para>When showing sockets, show the type of the socket.</para>
218 <term><option>--irreversible</option></term>
221 <para>Mark this transaction's jobs as irreversible. This prevents
222 future conflicting transactions from replacing these jobs.
223 The jobs can still be cancelled using the <command>cancel</command>
229 <term><option>--ignore-dependencies</option></term>
232 <para>When enqueuing a new job, ignore all its dependencies
233 and execute it immediately. If passed, no required units of
234 the unit passed will be pulled in, and no ordering
235 dependencies will be honored. This is mostly a debugging and
236 rescue tool for the administrator and should not be used by
242 <term><option>-i</option></term>
243 <term><option>--ignore-inhibitors</option></term>
246 <para>When system shutdown or a sleep state is requested,
247 ignore inhibitor locks. Applications can establish inhibitor
248 locks to avoid that certain important operations (such as CD
249 burning or suchlike) are interrupted by system shutdown or a
250 sleep state. Any user may take these locks and privileged
251 users may override these locks. If any locks are taken,
252 shutdown and sleep state requests will normally fail
253 (regardless if privileged or not) and a list of active locks
254 is printed. However, if <option>--ignore-inhibitors</option>
255 is specified, the locks are ignored and not printed, and the
256 operation attempted anyway, possibly requiring additional
262 <term><option>-q</option></term>
263 <term><option>--quiet</option></term>
266 <para>Suppress output to standard output in
267 <command>snapshot</command>,
268 <command>is-active</command>,
269 <command>is-failed</command>,
270 <command>enable</command> and
271 <command>disable</command>.</para>
276 <term><option>--no-block</option></term>
279 <para>Do not synchronously wait for the requested operation
280 to finish. If this is not specified, the job will be
281 verified, enqueued and <command>systemctl</command> will
282 wait until it is completed. By passing this argument, it is
283 only verified and enqueued.</para>
288 <term><option>--no-legend</option></term>
291 <para>Do not print a legend, i.e. the column headers and
292 the footer with hints.</para>
297 <term><option>--no-pager</option></term>
300 <para>Do not pipe output into a pager.</para>
305 <term><option>--system</option></term>
308 <para>Talk to the systemd system manager. (Default)</para>
313 <term><option>--user</option></term>
316 <para>Talk to the systemd manager of the calling
322 <term><option>--no-wall</option></term>
325 <para>Do not send wall message before halt, power-off,
331 <term><option>--global</option></term>
334 <para>When used with <command>enable</command> and
335 <command>disable</command>, operate on the global user
336 configuration directory, thus enabling or disabling a unit
337 file globally for all future logins of all users.</para>
342 <term><option>--no-reload</option></term>
345 <para>When used with <command>enable</command> and
346 <command>disable</command>, do not implicitly reload daemon
347 configuration after executing the changes.</para>
352 <term><option>--no-ask-password</option></term>
355 <para>When used with <command>start</command> and related
356 commands, disables asking for passwords. Background services
357 may require input of a password or passphrase string, for
358 example to unlock system hard disks or cryptographic
359 certificates. Unless this option is specified and the
360 command is invoked from a terminal,
361 <command>systemctl</command> will query the user on the
362 terminal for the necessary secrets. Use this option to
363 switch this behavior off. In this case, the password must be
364 supplied by some other means (for example graphical password
365 agents) or the service might fail. This also disables
366 querying the user for authentication for privileged
373 <term><option>--kill-who=</option></term>
376 <para>When used with <command>kill</command>, choose which
377 processes to kill. Must be one of <option>main</option>,
378 <option>control</option> or <option>all</option> to select
379 whether to kill only the main process of the unit, the
380 control process or all processes of the unit. If omitted,
381 defaults to <option>all</option>.</para>
387 <term><option>-s</option></term>
388 <term><option>--signal=</option></term>
391 <para>When used with <command>kill</command>, choose which
392 signal to send to selected processes. Must be one of the
393 well known signal specifiers such as <constant>SIGTERM</constant>, <constant>SIGINT</constant> or
394 <constant>SIGSTOP</constant>. If omitted, defaults to
395 <option>SIGTERM</option>.</para>
400 <term><option>-f</option></term>
401 <term><option>--force</option></term>
404 <para>When used with <command>enable</command>, overwrite
405 any existing conflicting symlinks.</para>
407 <para>When used with <command>halt</command>,
408 <command>poweroff</command>, <command>reboot</command> or
409 <command>kexec</command>, execute the selected operation
410 without shutting down all units. However, all processes will
411 be killed forcibly and all file systems are unmounted or
412 remounted read-only. This is hence a drastic but relatively
413 safe option to request an immediate reboot. If
414 <option>--force</option> is specified twice for these
415 operations, they will be executed immediately without
416 terminating any processes or umounting any file
417 systems. Warning: specifying <option>--force</option> twice
418 with any of these operations might result in data
424 <term><option>--root=</option></term>
428 <command>enable</command>/<command>disable</command>/<command>is-enabled</command>
429 (and related commands), use alternative root path when
430 looking for unit files.</para>
436 <term><option>--runtime</option></term>
439 <para>When used with <command>enable</command>,
440 <command>disable</command>, <command>is-enabled</command>
441 (and related commands), make changes only temporarily, so
442 that they are lost on the next reboot. This will have the
443 effect that changes are not made in subdirectories of
444 <filename>/etc</filename> but in <filename>/run</filename>,
445 with identical immediate effects, however, since the latter
446 is lost on reboot, the changes are lost too.</para>
448 <para>Similar, when used with
449 <command>set-property</command>, make changes only
450 temporarily, so that they are lost on the next
456 <term><option>-H</option></term>
457 <term><option>--host</option></term>
460 <para>Execute the operation remotely. Specify a hostname, or
461 username and hostname separated by <literal>@</literal>, to
462 connect to. This will use SSH to talk to the remote systemd
468 <term><option>-M</option></term>
469 <term><option>--machine=</option></term>
471 <listitem><para>Execute the operation on a local
472 container. Specify a container name to connect
473 to.</para></listitem>
477 <term><option>-n</option></term>
478 <term><option>--lines=</option></term>
481 <para>When used with <command>status</command>, controls the
482 number of journal lines to show, counting from the most
483 recent ones. Takes a positive integer argument. Defaults to
489 <term><option>-o</option></term>
490 <term><option>--output=</option></term>
493 <para>When used with <command>status</command>, controls the
494 formatting of the journal entries that are shown. For the
495 available choices, see
496 <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
497 Defaults to <literal>short</literal>.</para>
502 <term><option>--plain</option></term>
505 <para>When used with <command>list-dependencies</command>,
506 the output is printed as a list instead of a tree.</para>
514 <title>Commands</title>
516 <para>The following commands are understood:</para>
519 <title>Unit Commands</title>
523 <term><command>list-units</command></term>
526 <para>List known units (subject to limitations specified
527 with <option>-t</option>).</para>
529 <para>This is the default command.</para>
534 <term><command>list-sockets</command></term>
537 <para>List socket units ordered by the listening address. Produces output
540 LISTEN UNIT ACTIVATES
541 /dev/initctl systemd-initctl.socket systemd-initctl.service
543 [::]:22 sshd.socket sshd.service
544 kobject-uevent 1 systemd-udevd-kernel.socket systemd-udevd.service
548 Note: because the addresses might contains spaces, this output
549 is not suitable for programmatic consumption.
552 <para>See also the options <option>--show-types</option>,
553 <option>--all</option>, and <option>--failed</option>.</para>
558 <term><command>start <replaceable>NAME</replaceable>...</command></term>
561 <para>Start (activate) one or more units specified on the
566 <term><command>stop <replaceable>NAME</replaceable>...</command></term>
569 <para>Stop (deactivate) one or more units specified on the
574 <term><command>reload <replaceable>NAME</replaceable>...</command></term>
577 <para>Asks all units listed on the command line to reload
578 their configuration. Note that this will reload the
579 service-specific configuration, not the unit configuration
580 file of systemd. If you want systemd to reload the
581 configuration file of a unit, use the
582 <command>daemon-reload</command> command. In other words:
583 for the example case of Apache, this will reload Apache's
584 <filename>httpd.conf</filename> in the web server, not the
585 <filename>apache.service</filename> systemd unit
588 <para>This command should not be confused with the
589 <command>daemon-reload</command> or <command>load</command>
595 <term><command>restart <replaceable>NAME</replaceable>...</command></term>
598 <para>Restart one or more units specified on the command
599 line. If the units are not running yet, they will be
604 <term><command>try-restart <replaceable>NAME</replaceable>...</command></term>
607 <para>Restart one or more units specified on the command
608 line if the units are running. This does nothing if units are not
609 running. Note that, for compatibility with Red Hat init
610 scripts, <command>condrestart</command> is equivalent to this
615 <term><command>reload-or-restart <replaceable>NAME</replaceable>...</command></term>
618 <para>Reload one or more units if they support it. If not,
619 restart them instead. If the units are not running yet, they
620 will be started.</para>
624 <term><command>reload-or-try-restart <replaceable>NAME</replaceable>...</command></term>
627 <para>Reload one or more units if they support it. If not,
628 restart them instead. This does nothing if the units are not
629 running. Note that, for compatibility with SysV init scripts,
630 <command>force-reload</command> is equivalent to this
635 <term><command>isolate <replaceable>NAME</replaceable></command></term>
638 <para>Start the unit specified on the command line and its
639 dependencies and stop all others.</para>
641 <para>This is similar to changing the runlevel in a
642 traditional init system. The <command>isolate</command>
643 command will immediately stop processes that are not enabled
644 in the new unit, possibly including the graphical
645 environment or terminal you are currently using.</para>
647 <para>Note that this is allowed only on units where
648 <option>AllowIsolate=</option> is enabled. See
649 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
654 <term><command>kill <replaceable>NAME</replaceable>...</command></term>
657 <para>Send a signal to one or more processes of the
658 unit. Use <option>--kill-who=</option> to select which
659 process to kill. Use <option>--kill-mode=</option> to select
660 the kill mode and <option>--signal=</option> to select the
661 signal to send.</para>
665 <term><command>is-active <replaceable>NAME</replaceable>...</command></term>
668 <para>Check whether any of the specified units are active
669 (i.e. running). Returns an exit code 0 if at least one is
670 active, non-zero otherwise. Unless <option>--quiet</option>
671 is specified, this will also print the current unit state to
676 <term><command>is-failed <replaceable>NAME</replaceable>...</command></term>
679 <para>Check whether any of the specified units are in a "failed" state.
680 Returns an exit code 0 if at least one has failed, non-zero
681 otherwise. Unless <option>--quiet</option> is specified, this
682 will also print the current unit state to
687 <term><command>status [<replaceable>NAME</replaceable>...|<replaceable>PID</replaceable>...]</command></term>
690 <para>Show terse runtime status information about one or
691 more units, followed by most recent log data from the
692 journal. If no units are specified, show all units (subject
693 to limitations specified with <option>-t</option>). If a PID
694 is passed, show information about the unit the process
697 <para>This function is intended to generate human-readable
698 output. If you are looking for computer-parsable output, use
699 <command>show</command> instead.</para>
703 <term><command>show [<replaceable>NAME</replaceable>...|<replaceable>JOB</replaceable>...]</command></term>
706 <para>Show properties of one or more units, jobs, or the
707 manager itself. If no argument is specified, properties of
708 the manager will be shown. If a unit name is specified,
709 properties of the unit is shown, and if a job id is
710 specified, properties of the job is shown. By default, empty
711 properties are suppressed. Use <option>--all</option> to
712 show those too. To select specific properties to show, use
713 <option>--property=</option>. This command is intended to be
714 used whenever computer-parsable output is required. Use
715 <command>status</command> if you are looking for formatted
716 human-readable output.</para>
721 <term><command>set-property <replaceable>NAME</replaceable> <replaceable>ASSIGNMENT</replaceable>...</command></term>
724 <para>Set the specified unit properties at runtime where
725 this is supported. This allows changing configuration
726 parameter properties such as resource control settings at
727 runtime. Not all properties may be changed at runtime, but
728 many resource control settings (primarily those in
729 <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
730 may. The changes are applied instantly, and stored on disk
731 for future boots, unless <option>--runtime</option> is
732 passed, in which case the settings only apply until the
733 next reboot. The syntax of the property assignment follows
734 closely the syntax of assignments in unit files.</para>
736 <para>Example: <command>systemctl set-property foobar.service CPUShares=777</command></para>
738 <para>Note that this command allows changing multiple
739 properties at the same time, which is preferable over
740 setting them individually. Like unit file configuration
741 settings, assigning the empty list to list parameters will
742 reset the list.</para>
747 <term><command>help <replaceable>NAME</replaceable>...|<replaceable>PID</replaceable>...</command></term>
750 <para>Show manual pages for one or more units, if
751 available. If a PID is given, the manual pages for the unit
752 the process belongs to are shown.</para>
757 <term><command>reset-failed [<replaceable>NAME</replaceable>...]</command></term>
760 <para>Reset the <literal>failed</literal> state of the
761 specified units, or if no unit name is passed, reset the state of all
762 units. When a unit fails in some way (i.e. process exiting
763 with non-zero error code, terminating abnormally or timing
764 out), it will automatically enter the
765 <literal>failed</literal> state and its exit code and status
766 is recorded for introspection by the administrator until the
767 service is restarted or reset with this command.</para>
772 <term><command>list-dependencies <replaceable>NAME</replaceable></command></term>
775 <para>Shows required and wanted units of the specified
776 unit. If no unit is specified,
777 <filename>default.target</filename> is implied. Target units
778 are recursively expanded. When <option>--all</option> is
779 passed, all other units are recursively expanded as
787 <title>Unit File Commands</title>
791 <term><command>list-unit-files</command></term>
794 <para>List installed unit files.</para>
799 <term><command>enable <replaceable>NAME</replaceable>...</command></term>
802 <para>Enable one or more unit files or unit file instances,
803 as specified on the command line. This will create a number
804 of symlinks as encoded in the <literal>[Install]</literal>
805 sections of the unit files. After the symlinks have been
806 created, the systemd configuration is reloaded (in a way that
807 is equivalent to <command>daemon-reload</command>) to ensure
808 the changes are taken into account immediately. Note that
809 this does <emphasis>not</emphasis> have the effect of also
810 starting any of the units being enabled. If this
811 is desired, a separate <command>start</command> command must
812 be invoked for the unit. Also note that in case of instance
813 enablement, symlinks named the same as instances are created in
814 the install location, however they all point to the same
815 template unit file.</para>
817 <para>This command will print the actions executed. This
818 output may be suppressed by passing <option>--quiet</option>.
821 <para>Note that this operation creates only the suggested
822 symlinks for the units. While this command is the
823 recommended way to manipulate the unit configuration
824 directory, the administrator is free to make additional
825 changes manually by placing or removing symlinks in the
826 directory. This is particularly useful to create
827 configurations that deviate from the suggested default
828 installation. In this case, the administrator must make sure
829 to invoke <command>daemon-reload</command> manually as
830 necessary to ensure the changes are taken into account.
833 <para>Enabling units should not be confused with starting
834 (activating) units, as done by the <command>start</command>
835 command. Enabling and starting units is orthogonal: units
836 may be enabled without being started and started without
837 being enabled. Enabling simply hooks the unit into various
838 suggested places (for example, so that the unit is
839 automatically started on boot or when a particular kind of
840 hardware is plugged in). Starting actually spawns the daemon
841 process (in case of service units), or binds the socket (in
842 case of socket units), and so on.</para>
844 <para>Depending on whether <option>--system</option>,
845 <option>--user</option>, <option>--runtime</option>,
846 or <option>--global</option> is specified, this enables the unit
847 for the system, for the calling user only, for only this boot of
848 the system, or for all future logins of all users, or only this
849 boot. Note that in the last case, no systemd daemon
850 configuration is reloaded.</para>
855 <term><command>disable <replaceable>NAME</replaceable>...</command></term>
858 <para>Disables one or more units. This removes all symlinks
859 to the specified unit files from the unit configuration
860 directory, and hence undoes the changes made by
861 <command>enable</command>. Note however that this removes
862 all symlinks to the unit files (i.e. including manual
863 additions), not just those actually created by
864 <command>enable</command>. This call implicitly reloads the
865 systemd daemon configuration after completing the disabling
866 of the units. Note that this command does not implicitly
867 stop the units that are being disabled. If this is desired,
868 an additional <command>stop</command> command should be
869 executed afterwards.</para>
871 <para>This command will print the actions executed. This
872 output may be suppressed by passing <option>--quiet</option>.
875 <para>This command honors <option>--system</option>,
876 <option>--user</option>, <option>--runtime</option> and
877 <option>--global</option> in a similar way as
878 <command>enable</command>.</para>
883 <term><command>is-enabled <replaceable>NAME</replaceable>...</command></term>
886 <para>Checks whether any of the specified unit files are
887 enabled (as with <command>enable</command>). Returns an exit
888 code of 0 if at least one is enabled, non-zero
889 otherwise. Prints the current enable status. To suppress
890 this output, use <option>--quiet</option>.</para>
895 <term><command>reenable <replaceable>NAME</replaceable>...</command></term>
898 <para>Reenable one or more unit files, as specified on the
899 command line. This is a combination of
900 <command>disable</command> and <command>enable</command> and
901 is useful to reset the symlinks a unit is enabled with to
902 the defaults configured in the <literal>[Install]</literal>
903 section of the unit file.</para>
908 <term><command>preset <replaceable>NAME</replaceable>...</command></term>
911 <para>Reset one or more unit files, as specified on the
912 command line, to the defaults configured in the preset
913 policy files. This has the same effect as
914 <command>disable</command> or <command>enable</command>,
915 depending how the unit is listed in the preset files. For
916 more information on the preset policy format, see
917 <citerefentry><refentrytitle>systemd.preset</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
918 For more information on the concept of presets, please
920 <ulink url="http://freedesktop.org/wiki/Software/systemd/Preset">Preset</ulink>
926 <term><command>mask <replaceable>NAME</replaceable>...</command></term>
929 <para>Mask one or more unit files, as specified on the
930 command line. This will link these units to
931 <filename>/dev/null</filename>, making it impossible to
932 start them. This is a stronger version of
933 <command>disable</command>, since it prohibits all kinds of
934 activation of the unit, including manual activation. Use
935 this option with care. This honors the
936 <option>--runtime</option> option to only mask temporarily
937 until the next reoobt of the system.</para>
942 <term><command>unmask <replaceable>NAME</replaceable>...</command></term>
945 <para>Unmask one or more unit files, as specified on the
946 command line. This will undo the effect of
947 <command>mask</command>.</para>
952 <term><command>link <replaceable>FILENAME</replaceable>...</command></term>
955 <para>Link a unit file that is not in the unit file search
956 paths into the unit file search path. This requires an
957 absolute path to a unit file. The effect of this can be
958 undone with <command>disable</command>. The effect of this
959 command is that a unit file is available for
960 <command>start</command> and other commands although it
961 is not installed directly in the unit search path.</para>
966 <term><command>get-default</command></term>
969 <para>Get the default target specified
970 via <filename>default.target</filename> link.</para>
975 <term><command>set-default <replaceable>NAME</replaceable></command></term>
978 <para>Set the default target to boot into. Command links
979 <filename>default.target</filename> to the given unit.</para>
986 <title>Job Commands</title>
990 <term><command>list-jobs</command></term>
993 <para>List jobs that are in progress.</para>
997 <term><command>cancel <replaceable>JOB</replaceable>...</command></term>
1000 <para>Cancel one or more jobs specified on the command line
1001 by their numeric job IDs. If no job ID is specified, cancel
1002 all pending jobs.</para>
1009 <title>Snapshot Commands</title>
1013 <term><command>snapshot [<replaceable>NAME</replaceable>]</command></term>
1016 <para>Create a snapshot. If a snapshot name is specified,
1017 the new snapshot will be named after it. If none is
1018 specified, an automatic snapshot name is generated. In either
1019 case, the snapshot name used is printed to STDOUT, unless
1020 <option>--quiet</option> is specified.</para>
1022 <para>A snapshot refers to a saved state of the systemd
1023 manager. It is implemented itself as a unit that is
1024 generated dynamically with this command and has dependencies
1025 on all units active at the time. At a later time, the user
1026 may return to this state by using the
1027 <command>isolate</command> command on the snapshot unit.
1030 <para>Snapshots are only useful for saving and restoring
1031 which units are running or are stopped, they do not
1032 save/restore any other state. Snapshots are dynamic and lost
1037 <term><command>delete <replaceable>NAME</replaceable>...</command></term>
1040 <para>Remove a snapshot previously created with
1041 <command>snapshot</command>.</para>
1048 <title>Environment Commands</title>
1052 <term><command>show-environment</command></term>
1055 <para>Dump the systemd manager environment block. The
1056 environment block will be dumped in straight-forward form
1057 suitable for sourcing into a shell script. This environment
1058 block will be passed to all processes the manager
1063 <term><command>set-environment <replaceable>VARIABLE=VALUE</replaceable>...</command></term>
1066 <para>Set one or more systemd manager environment variables,
1067 as specified on the command line.</para>
1071 <term><command>unset-environment <replaceable>VARIABLE</replaceable>...</command></term>
1074 <para>Unset one or more systemd manager environment
1075 variables. If only a variable name is specified, it will be
1076 removed regardless of its value. If a variable and a value
1077 are specified, the variable is only removed if it has the
1078 specified value.</para>
1085 <title>Manager Lifecycle Commands</title>
1089 <term><command>daemon-reload</command></term>
1092 <para>Reload systemd manager configuration. This will reload
1093 all unit files and recreate the entire dependency
1094 tree. While the daemon is being reloaded, all sockets systemd
1095 listens on on behalf of user configuration will stay
1096 accessible.</para> <para>This command should not be confused
1097 with the <command>load</command> or
1098 <command>reload</command> commands.</para>
1102 <term><command>daemon-reexec</command></term>
1105 <para>Reexecute the systemd manager. This will serialize the
1106 manager state, reexecute the process and deserialize the
1107 state again. This command is of little use except for
1108 debugging and package upgrades. Sometimes, it might be
1109 helpful as a heavy-weight <command>daemon-reload</command>.
1110 While the daemon is being reexecuted, all sockets systemd listening
1111 on behalf of user configuration will stay accessible.
1119 <title>System Commands</title>
1123 <term><command>default</command></term>
1126 <para>Enter default mode. This is mostly equivalent to
1127 <command>isolate default.target</command>.</para>
1131 <term><command>rescue</command></term>
1134 <para>Enter rescue mode. This is mostly equivalent to
1135 <command>isolate rescue.target</command>, but also prints a
1136 wall message to all users.</para>
1140 <term><command>emergency</command></term>
1143 <para>Enter emergency mode. This is mostly equivalent to
1144 <command>isolate emergency.target</command>, but also prints
1145 a wall message to all users.</para>
1149 <term><command>halt</command></term>
1152 <para>Shut down and halt the system. This is mostly equivalent to
1153 <command>start halt.target --irreversible</command>, but also
1154 prints a wall message to all users. If combined with
1155 <option>--force</option>, shutdown of all running services is
1156 skipped, however all processes are killed and all file
1157 systems are unmounted or mounted read-only, immediately
1158 followed by the system halt. If <option>--force</option> is
1159 specified twice, the operation is immediately executed
1160 without terminating any processes or unmounting any file
1161 systems. This may result in data loss.</para>
1165 <term><command>poweroff</command></term>
1168 <para>Shut down and power-off the system. This is mostly
1169 equivalent to <command>start poweroff.target --irreversible</command>,
1170 but also prints a wall message to all users. If combined with
1171 <option>--force</option>, shutdown of all running services is
1172 skipped, however all processes are killed and all file
1173 systems are unmounted or mounted read-only, immediately
1174 followed by the powering off. If <option>--force</option> is
1175 specified twice, the operation is immediately executed
1176 without terminating any processes or unmounting any file
1177 systems. This may result in data loss.</para>
1181 <term><command>reboot <optional><replaceable>arg</replaceable></optional></command></term>
1184 <para>Shut down and reboot the system. This is mostly
1185 equivalent to <command>start reboot.target --irreversible</command>,
1186 but also prints a wall message to all users. If combined with
1187 <option>--force</option>, shutdown of all running services is
1188 skipped, however all processes are killed and all file
1189 systems are unmounted or mounted read-only, immediately
1190 followed by the reboot. If <option>--force</option> is
1191 specified twice, the operation is immediately executed
1192 without terminating any processes or unmounting any file
1193 systems. This may result in data loss.</para>
1195 <para>If the optional argument
1196 <replaceable>arg</replaceable> is given, it will be passed
1197 as the optional argument to the
1198 <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1199 system call. The value is architecture and firmware
1200 specific. As an example, <literal>recovery</literal> might
1201 be used to trigger system recovery, and
1202 <literal>fota</literal> might be used to trigger a
1203 <quote>firmware over the air</quote> update.</para>
1207 <term><command>kexec</command></term>
1210 <para>Shut down and reboot the system via kexec. This is
1211 mostly equivalent to <command>start kexec.target --irreversible</command>,
1212 but also prints a wall message to all users. If combined
1213 with <option>--force</option>, shutdown of all running
1214 services is skipped, however all processes are killed and
1215 all file systems are unmounted or mounted read-only,
1216 immediately followed by the reboot.</para>
1220 <term><command>exit</command></term>
1223 <para>Ask the systemd manager to quit. This is only
1224 supported for user service managers (i.e. in conjunction
1225 with the <option>--user</option> option) and will fail
1231 <term><command>suspend</command></term>
1234 <para>Suspend the system. This will trigger activation of
1235 the special <filename>suspend.target</filename> target.
1240 <term><command>hibernate</command></term>
1243 <para>Hibernate the system. This will trigger activation of
1244 the special <filename>hibernate.target</filename> target.
1249 <term><command>hybrid-sleep</command></term>
1252 <para>Hibernate and suspend the system. This will trigger
1253 activation of the special
1254 <filename>hybrid-sleep.target</filename> target.</para>
1258 <term><command>switch-root <replaceable>ROOT</replaceable> [<replaceable>INIT</replaceable>]</command></term>
1261 <para>Switches to a different root directory and executes a
1262 new system manager process below it. This is intended for
1263 usage in initial RAM disks ("initrd"), and will transition
1264 from the initrd's system manager process (a.k.a "init"
1265 process) to the main system manager process. This call takes two
1266 arguments: the directory that is to become the new root directory, and
1267 the path to the new system manager binary below it to
1268 execute as PID 1. If the latter is omitted or the empty
1269 string, a systemd binary will automatically be searched for
1270 and used as init. If the system manager path is omitted or
1271 equal to the empty string, the state of the initrd's system
1272 manager process is passed to the main system manager, which
1273 allows later introspection of the state of the services
1274 involved in the initrd boot.</para>
1283 <title>Exit status</title>
1285 <para>On success, 0 is returned, a non-zero failure
1286 code otherwise.</para>
1290 <title>Environment</title>
1292 <variablelist class='environment-variables'>
1294 <term><varname>$SYSTEMD_PAGER</varname></term>
1297 <para>Pager to use when <option>--no-pager</option> is not
1298 given; overrides <varname>$PAGER</varname>. Setting this to
1299 an empty string or the value <literal>cat</literal> is
1300 equivalent to passing
1301 <option>--no-pager</option>.</para>
1308 <title>See Also</title>
1310 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1311 <citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1312 <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1313 <citerefentry><refentrytitle>loginctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1314 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1315 <citerefentry><refentrytitle>systemd.resource-management</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1316 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1317 <citerefentry><refentrytitle>wall</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1318 <citerefentry><refentrytitle>systemd.preset</refentrytitle><manvolnum>5</manvolnum></citerefentry>