1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3 "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
4 <!ENTITY % entities SYSTEM "custom-entities.ent" >
9 This file is part of systemd.
11 Copyright 2010 Lennart Poettering
13 systemd is free software; you can redistribute it and/or modify it
14 under the terms of the GNU Lesser General Public License as published by
15 the Free Software Foundation; either version 2.1 of the License, or
16 (at your option) any later version.
18 systemd is distributed in the hope that it will be useful, but
19 WITHOUT ANY WARRANTY; without even the implied warranty of
20 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 Lesser General Public License for more details.
23 You should have received a copy of the GNU Lesser General Public License
24 along with systemd; If not, see <http://www.gnu.org/licenses/>.
27 <refentry id="systemd.unit">
30 <title>systemd.unit</title>
31 <productname>systemd</productname>
35 <contrib>Developer</contrib>
36 <firstname>Lennart</firstname>
37 <surname>Poettering</surname>
38 <email>lennart@poettering.net</email>
44 <refentrytitle>systemd.unit</refentrytitle>
45 <manvolnum>5</manvolnum>
49 <refname>systemd.unit</refname>
50 <refpurpose>Unit configuration</refpurpose>
54 <para><filename><replaceable>service</replaceable>.service</filename>,
55 <filename><replaceable>socket</replaceable>.socket</filename>,
56 <filename><replaceable>device</replaceable>.device</filename>,
57 <filename><replaceable>mount</replaceable>.mount</filename>,
58 <filename><replaceable>automount</replaceable>.automount</filename>,
59 <filename><replaceable>swap</replaceable>.swap</filename>,
60 <filename><replaceable>target</replaceable>.target</filename>,
61 <filename><replaceable>path</replaceable>.path</filename>,
62 <filename><replaceable>timer</replaceable>.timer</filename>,
63 <filename><replaceable>snapshot</replaceable>.snapshot</filename>,
64 <filename><replaceable>slice</replaceable>.slice</filename>,
65 <filename><replaceable>scope</replaceable>.scope</filename></para>
67 <para><literallayout><filename>/etc/systemd/system/*</filename>
68 <filename>/run/systemd/system/*</filename>
69 <filename>/usr/lib/systemd/system/*</filename>
70 <filename>...</filename>
71 </literallayout></para>
73 <para><literallayout><filename>$XDG_CONFIG_HOME/systemd/user/*</filename>
74 <filename>$HOME/.config/systemd/user/*</filename>
75 <filename>/etc/systemd/user/*</filename>
76 <filename>/run/systemd/user/*</filename>
77 <filename>/usr/lib/systemd/user/*</filename>
78 <filename>...</filename>
79 </literallayout></para>
83 <title>Description</title>
85 <para>A unit configuration file encodes information
86 about a service, a socket, a device, a mount point, an
87 automount point, a swap file or partition, a start-up
88 target, a watched file system path, a timer controlled
90 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
91 a temporary system state snapshot, a resource
92 management slice or a group of externally created
93 processes. The syntax is inspired by <ulink
94 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
95 Desktop Entry Specification</ulink>
96 <filename>.desktop</filename> files, which are in turn
97 inspired by Microsoft Windows
98 <filename>.ini</filename> files.</para>
100 <para>This man page lists the common configuration
101 options of all the unit types. These options need to
102 be configured in the [Unit] or [Install]
103 sections of the unit files.</para>
105 <para>In addition to the generic [Unit] and [Install]
106 sections described here, each unit may have a
107 type-specific section, e.g. [Service] for a service
108 unit. See the respective man pages for more
110 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
111 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
112 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
113 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
114 <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
115 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
116 <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
117 <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
118 <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
119 <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
120 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
121 <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
124 <para>Various settings are allowed to be specified
125 more than once, in which case the interpretation
126 depends on the setting. Often, multiple settings form
127 a list, and setting to an empty value "resets", which
128 means that previous assignments are ignored. When this
129 is allowed, it is mentioned in the description of the
130 setting. Note that using multiple assignments to the
131 same value makes the unit file incompatible with
132 parsers for the XDG <filename>.desktop</filename> file
135 <para>Unit files are loaded from a set of paths
136 determined during compilation, described in the next section.
139 <para>Unit files may contain additional options on top
140 of those listed here. If systemd encounters an unknown
141 option, it will write a warning log message but
142 continue loading the unit. If an option is prefixed
143 with <option>X-</option>, it is ignored completely by
144 systemd. Applications may use this to include
145 additional information in the unit files.</para>
147 <para>Boolean arguments used in unit files can be
148 written in various formats. For positive settings the
149 strings <option>1</option>, <option>yes</option>,
150 <option>true</option> and <option>on</option> are
151 equivalent. For negative settings, the strings
152 <option>0</option>, <option>no</option>,
153 <option>false</option> and <option>off</option> are
156 <para>Time span values encoded in unit files can be
157 written in various formats. A stand-alone number
158 specifies a time in seconds. If suffixed with a time
159 unit, the unit is honored. A concatenation of multiple
160 values with units is supported, in which case the
161 values are added up. Example: "50" refers to 50
162 seconds; "2min 200ms" refers to 2 minutes plus 200
163 milliseconds, i.e. 120200ms. The following time units
164 are understood: s, min, h, d, w, ms, us. For details
166 <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
168 <para>Empty lines and lines starting with # or ; are
169 ignored. This may be used for commenting. Lines ending
170 in a backslash are concatenated with the following
171 line while reading and the backslash is replaced by a
172 space character. This may be used to wrap long lines.</para>
174 <para>Along with a unit file
175 <filename>foo.service</filename>, the directory
176 <filename>foo.service.wants/</filename> may exist. All
177 unit files symlinked from such a directory are
178 implicitly added as dependencies of type
179 <varname>Wanted=</varname> to the unit. This is useful
180 to hook units into the start-up of other units,
181 without having to modify their unit files. For details
182 about the semantics of <varname>Wanted=</varname>, see
183 below. The preferred way to create symlinks in the
184 <filename>.wants/</filename> directory of a unit file
185 is with the <command>enable</command> command of the
186 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
187 tool which reads information from the [Install]
188 section of unit files (see below). A similar
189 functionality exists for <varname>Requires=</varname>
190 type dependencies as well, the directory suffix is
191 <filename>.requires/</filename> in this case.</para>
193 <para>Along with a unit file
194 <filename>foo.service</filename>, a directory
195 <filename>foo.service.d/</filename> may exist. All
196 files with the suffix <literal>.conf</literal> from
197 this directory will be parsed after the file itself is
198 parsed. This is useful to alter or add configuration
199 settings to a unit, without having to modify their
200 unit files. Make sure that the file that is included
201 has the appropriate section headers before any
204 <para>Note that while systemd offers a flexible
205 dependency system between units it is recommended to
206 use this functionality only sparingly and instead rely
207 on techniques such as bus-based or socket-based
208 activation which make dependencies implicit, resulting
209 in a both simpler and more flexible system.</para>
211 <para>Some unit names reflect paths existing in the
212 file system namespace. Example: a device unit
213 <filename>dev-sda.device</filename> refers to a device
214 with the device node <filename noindex='true'>/dev/sda</filename> in
215 the file system namespace. If this applies, a special
216 way to escape the path name is used, so that the
217 result is usable as part of a filename. Basically,
218 given a path, "/" is replaced by "-", and all
219 unprintable characters and the "-" are replaced by
220 C-style "\x20" escapes. The root directory "/" is
221 encoded as single dash, while otherwise the initial
222 and ending "/" is removed from all paths during
223 transformation. This escaping is reversible.</para>
225 <para>Optionally, units may be instantiated from a
226 template file at runtime. This allows creation of
227 multiple units from a single configuration file. If
228 systemd looks for a unit configuration file, it will
229 first search for the literal unit name in the
230 file system. If that yields no success and the unit
231 name contains an <literal>@</literal> character, systemd will look for a
232 unit template that shares the same name but with the
233 instance string (i.e. the part between the <literal>@</literal> character
234 and the suffix) removed. Example: if a service
235 <filename>getty@tty3.service</filename> is requested
236 and no file by that name is found, systemd will look
237 for <filename>getty@.service</filename> and
238 instantiate a service from that configuration file if
241 <para>To refer to the instance string from
242 within the configuration file you may use the special
243 <literal>%i</literal> specifier in many of the
244 configuration options. See below for details.</para>
246 <para>If a unit file is empty (i.e. has the file size
247 0) or is symlinked to <filename>/dev/null</filename>,
248 its configuration will not be loaded and it appears
249 with a load state of <literal>masked</literal>, and
250 cannot be activated. Use this as an effective way to
251 fully disable a unit, making it impossible to start it
252 even manually.</para>
254 <para>The unit file format is covered by the
256 url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
257 Stability Promise</ulink>.</para>
262 <title>Unit Load Path</title>
264 <para>Unit files are loaded from a set of paths
265 determined during compilation, described in the two
266 tables below. Unit files found in directories listed
267 earlier override files with the same name in
268 directories lower in the list.</para>
270 <para>When systemd is running in user mode
271 (<option>--user</option>) and the variable
272 <varname>$SYSTEMD_UNIT_PATH</varname> is set, this
273 contents of this variable overrides the unit load
279 Load path when running in system mode (<option>--system</option>).
283 <colspec colname='path' />
284 <colspec colname='expl' />
288 <entry>Description</entry>
293 <entry><filename>/etc/systemd/system</filename></entry>
294 <entry>Local configuration</entry>
297 <entry><filename>/run/systemd/system</filename></entry>
298 <entry>Runtime units</entry>
301 <entry><filename>/usr/lib/systemd/system</filename></entry>
302 <entry>Units of installed packages</entry>
310 Load path when running in user mode (<option>--user</option>).
314 <colspec colname='path' />
315 <colspec colname='expl' />
319 <entry>Description</entry>
324 <entry><filename>$XDG_CONFIG_HOME/systemd/user</filename></entry>
325 <entry>User configuration (only used when $XDG_CONFIG_HOME is set)</entry>
328 <entry><filename>$HOME/.config/systemd/user</filename></entry>
329 <entry>User configuration (only used when $XDG_CONFIG_HOME is not set)</entry>
332 <entry><filename>/etc/systemd/user</filename></entry>
333 <entry>Local configuration</entry>
336 <entry><filename>/run/systemd/user</filename></entry>
337 <entry>Runtime units</entry>
340 <entry><filename>/usr/lib/systemd/user</filename></entry>
341 <entry>Units of installed packages</entry>
347 <para>Additional units might be loaded into systemd
348 ("linked") from directories not on the unit load
349 path. See the <command>link</command> command for
350 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. Also,
351 some units are dynamically created via generators
353 url="http://www.freedesktop.org/wiki/Software/systemd/Generators/">Generators</ulink>.
358 <title>[Unit] Section Options</title>
360 <para>Unit file may include a [Unit] section, which
361 carries generic information about the unit that is not
362 dependent on the type of unit:</para>
364 <variablelist class='unit-directives'>
367 <term><varname>Description=</varname></term>
368 <listitem><para>A free-form string
369 describing the unit. This is intended
370 for use in UIs to show descriptive
371 information along with the unit
372 name. The description should contain a name
373 that means something to the end user.
374 <literal>Apache2 Web Server</literal> is a good
375 example. Bad examples are
376 <literal>high-performance light-weight HTTP
377 server</literal> (too generic) or
378 <literal>Apache2</literal> (too specific and
379 meaningless for people who do not know
380 Apache).</para></listitem>
384 <term><varname>Documentation=</varname></term>
385 <listitem><para>A space-separated list
386 of URIs referencing documentation for
388 configuration. Accepted are only URIs
390 <literal>http://</literal>,
391 <literal>https://</literal>,
392 <literal>file:</literal>,
393 <literal>info:</literal>,
394 <literal>man:</literal>. For more
395 information about the syntax of these
397 <citerefentry><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
398 URIs should be listed in order of
399 relevance, starting with the most
400 relevant. It is a good idea to first
401 reference documentation that explains
402 what the unit's purpose is, followed
403 by how it is configured, followed by
404 any other related documentation. This
405 option may be specified more than once,
406 in which case the specified list of
407 URIs is merged. If the empty string is
408 assigned to this option, the list is
409 reset and all prior assignments will
410 have no effect.</para></listitem>
414 <term><varname>Requires=</varname></term>
416 <listitem><para>Configures requirement
417 dependencies on other units. If this
418 unit gets activated, the units listed
419 here will be activated as well. If one
420 of the other units gets deactivated or
421 its activation fails, this unit will
422 be deactivated. This option may be
423 specified more than once or multiple
424 space-separated units may be specified
425 in one option in which case
426 requirement dependencies for all
427 listed names will be created. Note
428 that requirement dependencies do not
429 influence the order in which services
430 are started or stopped. This has to be
431 configured independently with the
432 <varname>After=</varname> or
433 <varname>Before=</varname> options. If
435 <filename>foo.service</filename>
437 <filename>bar.service</filename> as
439 <varname>Requires=</varname> and no
440 ordering is configured with
441 <varname>After=</varname> or
442 <varname>Before=</varname>, then both
443 units will be started simultaneously
444 and without any delay between them if
445 <filename>foo.service</filename> is
446 activated. Often it is a better choice
447 to use <varname>Wants=</varname>
449 <varname>Requires=</varname> in order
450 to achieve a system that is more
451 robust when dealing with failing
454 <para>Note that dependencies of this
455 type may also be configured outside of
456 the unit configuration file by
457 adding a symlink to a
458 <filename>.requires/</filename> directory
459 accompanying the unit file. For
460 details see above.</para></listitem>
464 <term><varname>RequiresOverridable=</varname></term>
466 <listitem><para>Similar to
467 <varname>Requires=</varname>.
468 Dependencies listed in
469 <varname>RequiresOverridable=</varname>
470 which cannot be fulfilled or fail to
471 start are ignored if the startup was
472 explicitly requested by the user. If
473 the start-up was pulled in indirectly
474 by some dependency or automatic
475 start-up of units that is not
476 requested by the user, this dependency
477 must be fulfilled and otherwise the
478 transaction fails. Hence, this option
479 may be used to configure dependencies
480 that are normally honored unless the
481 user explicitly starts up the unit, in
482 which case whether they failed or not
483 is irrelevant.</para></listitem>
487 <term><varname>Requisite=</varname></term>
488 <term><varname>RequisiteOverridable=</varname></term>
490 <listitem><para>Similar to
491 <varname>Requires=</varname> and
492 <varname>RequiresOverridable=</varname>,
493 respectively. However, if the units
494 listed here are not started already,
495 they will not be started and the
496 transaction will fail immediately.
501 <term><varname>Wants=</varname></term>
503 <listitem><para>A weaker version of
504 <varname>Requires=</varname>. Units
505 listed in this option will be started
506 if the configuring unit is. However,
507 if the listed units fail to start
508 or cannot be added to the transaction,
509 this has no impact on the validity of
510 the transaction as a whole. This is
511 the recommended way to hook start-up
512 of one unit to the start-up of another
515 <para>Note that dependencies of this
516 type may also be configured outside of
517 the unit configuration file by adding
519 <filename>.wants/</filename> directory
520 accompanying the unit file. For
521 details, see above.</para></listitem>
525 <term><varname>BindsTo=</varname></term>
527 <listitem><para>Configures requirement
528 dependencies, very similar in style to
529 <varname>Requires=</varname>, however
530 in addition to this behavior, it also
531 declares that this unit is stopped
532 when any of the units listed suddenly
533 disappears. Units can suddenly,
534 unexpectedly disappear if a service
535 terminates on its own choice, a device
536 is unplugged or a mount point
537 unmounted without involvement of
538 systemd.</para></listitem>
542 <term><varname>PartOf=</varname></term>
544 <listitem><para>Configures dependencies
545 similar to <varname>Requires=</varname>,
546 but limited to stopping and restarting
547 of units. When systemd stops or restarts
548 the units listed here, the action is
549 propagated to this unit.
550 Note that this is a one-way dependency —
551 changes to this unit do not affect the
557 <term><varname>Conflicts=</varname></term>
559 <listitem><para>A space-separated list
560 of unit names. Configures negative
561 requirement dependencies. If a unit
562 has a <varname>Conflicts=</varname>
563 setting on another unit, starting the
564 former will stop the latter and vice
565 versa. Note that this setting is
566 independent of and orthogonal to the
567 <varname>After=</varname> and
568 <varname>Before=</varname> ordering
571 <para>If a unit A that conflicts with
572 a unit B is scheduled to be started at
573 the same time as B, the transaction
574 will either fail (in case both are
575 required part of the transaction) or
576 be modified to be fixed (in case one
577 or both jobs are not a required part
578 of the transaction). In the latter
579 case, the job that is not the required
580 will be removed, or in case both are
581 not required, the unit that conflicts
582 will be started and the unit that is
584 stopped.</para></listitem>
588 <term><varname>Before=</varname></term>
589 <term><varname>After=</varname></term>
591 <listitem><para>A space-separated list
592 of unit names. Configures ordering
593 dependencies between units. If a unit
594 <filename>foo.service</filename>
596 <option>Before=bar.service</option>
597 and both units are being started,
598 <filename>bar.service</filename>'s
599 start-up is delayed until
600 <filename>foo.service</filename> is
601 started up. Note that this setting is
602 independent of and orthogonal to the
603 requirement dependencies as configured
604 by <varname>Requires=</varname>. It is
605 a common pattern to include a unit
607 <varname>After=</varname> and
608 <varname>Requires=</varname> option, in
609 which case the unit listed will be
610 started before the unit that is
611 configured with these options. This
612 option may be specified more than
613 once, in which case ordering
614 dependencies for all listed names are
615 created. <varname>After=</varname> is
617 <varname>Before=</varname>, i.e. while
618 <varname>After=</varname> ensures that
619 the configured unit is started after
620 the listed unit finished starting up,
621 <varname>Before=</varname> ensures the
622 opposite, i.e. that the configured
623 unit is fully started up before the
624 listed unit is started. Note that when
625 two units with an ordering dependency
626 between them are shut down, the
627 inverse of the start-up order is
628 applied. i.e. if a unit is configured
629 with <varname>After=</varname> on
630 another unit, the former is stopped
631 before the latter if both are shut
632 down. If one unit with an ordering
633 dependency on another unit is shut
634 down while the latter is started up,
635 the shut down is ordered before the
636 start-up regardless of whether the
637 ordering dependency is actually of
638 type <varname>After=</varname> or
639 <varname>Before=</varname>. If two
640 units have no ordering dependencies
641 between them, they are shut down or
642 started up simultaneously, and no
644 place. </para></listitem>
648 <term><varname>OnFailure=</varname></term>
650 <listitem><para>A space-separated list
651 of one or more units that are
652 activated when this unit enters the
653 <literal>failed</literal>
654 state.</para></listitem>
658 <term><varname>PropagatesReloadTo=</varname></term>
659 <term><varname>ReloadPropagatedFrom=</varname></term>
661 <listitem><para>A space-separated list
662 of one or more units where reload
663 requests on this unit will be
664 propagated to, or reload requests on
665 the other unit will be propagated to
666 this unit, respectively. Issuing a
667 reload request on a unit will
668 automatically also enqueue a reload
669 request on all units that the reload
670 request shall be propagated to via
671 these two settings.</para></listitem>
675 <term><varname>JoinsNamespaceOf=</varname></term>
677 <listitem><para>For units that start
678 processes (such as service units),
679 lists one or more other units whose
680 network and/or temporary file
681 namespace to join. This only applies
682 to unit types which support the
683 <varname>PrivateNetwork=</varname> and
684 <varname>PrivateTmp=</varname>
686 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
687 for details). If a unit that has this
688 setting set is started, its processes
690 <filename>/tmp</filename>,
691 <filename>/tmp/var</filename> and
692 network namespace as one listed unit
693 that is started. If multiple listed
694 units are already started, it is not
695 defined which namespace is
696 joined. Note that this setting only
698 <varname>PrivateNetwork=</varname>
699 and/or <varname>PrivateTmp=</varname>
700 is enabled for both the unit that
701 joins the namespace and the unit whose
702 namespace is joined.</para></listitem>
706 <term><varname>RequiresMountsFor=</varname></term>
708 <listitem><para>Takes a space-separated
709 list of absolute paths. Automatically
710 adds dependencies of type
711 <varname>Requires=</varname> and
712 <varname>After=</varname> for all
713 mount units required to access the
714 specified path.</para></listitem>
718 <term><varname>OnFailureJobMode=</varname></term>
720 <listitem><para>Takes a value of
721 <literal>fail</literal>,
722 <literal>replace</literal>,
723 <literal>replace-irreversibly</literal>,
724 <literal>isolate</literal>,
725 <literal>flush</literal>,
726 <literal>ignore-dependencies</literal>
728 <literal>ignore-requirements</literal>. Defaults
730 <literal>replace</literal>. Specifies
731 how the units listed in
732 <varname>OnFailure=</varname> will be
734 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
735 <option>--job-mode=</option> option
736 for details on the possible values. If
738 <literal>isolate</literal>, only a
739 single unit may be listed in
740 <varname>OnFailure=</varname>..</para></listitem>
744 <term><varname>IgnoreOnIsolate=</varname></term>
746 <listitem><para>Takes a boolean
747 argument. If <option>true</option>,
748 this unit will not be stopped when
749 isolating another unit. Defaults to
750 <option>false</option>.</para></listitem>
754 <term><varname>IgnoreOnSnapshot=</varname></term>
756 <listitem><para>Takes a boolean
757 argument. If <option>true</option>,
758 this unit will not be included in
759 snapshots. Defaults to
760 <option>true</option> for device and
761 snapshot units, <option>false</option>
762 for the others.</para></listitem>
766 <term><varname>StopWhenUnneeded=</varname></term>
768 <listitem><para>Takes a boolean
769 argument. If <option>true</option>,
770 this unit will be stopped when it is
771 no longer used. Note that in order to
772 minimize the work to be executed,
773 systemd will not stop units by default
774 unless they are conflicting with other
775 units, or the user explicitly
776 requested their shut down. If this
777 option is set, a unit will be
778 automatically cleaned up if no other
779 active unit requires it. Defaults to
780 <option>false</option>.</para></listitem>
784 <term><varname>RefuseManualStart=</varname></term>
785 <term><varname>RefuseManualStop=</varname></term>
787 <listitem><para>Takes a boolean
788 argument. If <option>true</option>,
789 this unit can only be activated
790 or deactivated indirectly. In
791 this case, explicit start-up
792 or termination requested by the
793 user is denied, however if it is
794 started or stopped as a
795 dependency of another unit, start-up
796 or termination will succeed. This
797 is mostly a safety feature to ensure
798 that the user does not accidentally
799 activate units that are not intended
800 to be activated explicitly, and not
801 accidentally deactivate units that are
802 not intended to be deactivated.
803 These options default to
804 <option>false</option>.</para></listitem>
808 <term><varname>AllowIsolate=</varname></term>
810 <listitem><para>Takes a boolean
811 argument. If <option>true</option>,
812 this unit may be used with the
813 <command>systemctl isolate</command>
814 command. Otherwise, this will be
815 refused. It probably is a good idea to
816 leave this disabled except for target
817 units that shall be used similar to
818 runlevels in SysV init systems, just
819 as a precaution to avoid unusable
820 system states. This option defaults to
821 <option>false</option>.</para></listitem>
825 <term><varname>DefaultDependencies=</varname></term>
827 <listitem><para>Takes a boolean
828 argument. If <option>true</option>,
829 (the default), a few default
830 dependencies will implicitly be
831 created for the unit. The actual
832 dependencies created depend on the
833 unit type. For example, for service
834 units, these dependencies ensure that
835 the service is started only after
836 basic system initialization is
837 completed and is properly terminated on
838 system shutdown. See the respective
839 man pages for details. Generally, only
840 services involved with early boot or
841 late shutdown should set this option
842 to <option>false</option>. It is
843 highly recommended to leave this
844 option enabled for the majority of
845 common units. If set to
846 <option>false</option>, this option
847 does not disable all implicit
848 dependencies, just non-essential
849 ones.</para></listitem>
853 <term><varname>JobTimeoutSec=</varname></term>
855 <listitem><para>When clients are
856 waiting for a job of this unit to
857 complete, time out after the specified
858 time. If this time limit is reached,
859 the job will be cancelled, the unit
860 however will not change state or even
861 enter the <literal>failed</literal>
862 mode. This value defaults to 0 (job
863 timeouts disabled), except for device
864 units. NB: this timeout is independent
865 from any unit-specific timeout (for
866 example, the timeout set with
867 <varname>Timeout=</varname> in service
868 units) as the job timeout has no
869 effect on the unit itself, only on the
870 job that might be pending for it. Or
871 in other words: unit-specific timeouts
872 are useful to abort unit state
873 changes, and revert them. The job
874 timeout set with this option however
875 is useful to abort only the job
876 waiting for the unit state to
877 change.</para></listitem>
881 <term><varname>ConditionArchitecture=</varname></term>
882 <term><varname>ConditionVirtualization=</varname></term>
883 <term><varname>ConditionHost=</varname></term>
884 <term><varname>ConditionKernelCommandLine=</varname></term>
885 <term><varname>ConditionSecurity=</varname></term>
886 <term><varname>ConditionCapability=</varname></term>
887 <term><varname>ConditionACPower=</varname></term>
888 <term><varname>ConditionPathExists=</varname></term>
889 <term><varname>ConditionPathExistsGlob=</varname></term>
890 <term><varname>ConditionPathIsDirectory=</varname></term>
891 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
892 <term><varname>ConditionPathIsMountPoint=</varname></term>
893 <term><varname>ConditionPathIsReadWrite=</varname></term>
894 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
895 <term><varname>ConditionFileNotEmpty=</varname></term>
896 <term><varname>ConditionFileIsExecutable=</varname></term>
897 <term><varname>ConditionNull=</varname></term>
899 <listitem><para>Before starting a unit
900 verify that the specified condition is
901 true. If it is not true, the starting
902 of the unit will be skipped, however
903 all ordering dependencies of it are
904 still respected. A failing condition
905 will not result in the unit being
906 moved into a failure state. The
907 condition is checked at the time the
908 queued start job is to be
911 <para><varname>ConditionArchitecture=</varname>
912 may be used to check whether the
913 system is running on a specific
914 architecture. Takes one of
915 <varname>x86</varname>,
916 <varname>x86-64</varname>,
917 <varname>ppc</varname>,
918 <varname>ppc64</varname>,
919 <varname>ia64</varname>,
920 <varname>parisc</varname>,
921 <varname>parisc64</varname>,
922 <varname>s390</varname>,
923 <varname>s390x</varname>,
924 <varname>sparc</varname>,
925 <varname>sparc64</varname>,
926 <varname>mips</varname>,
927 <varname>mips64</varname>,
928 <varname>alpha</varname>,
929 <varname>arm</varname>,
930 <varname>arm-be</varname>,
931 <varname>arm64</varname>,
932 <varname>arm64-be</varname>,
933 <varname>sh</varname>,
934 <varname>sh64</varname>,
935 <varname>m86k</varname> to test
936 against a specific architecture. The
937 architecture is determined from the
938 information returned by
939 <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
940 and is thus subject to
941 <citerefentry><refentrytitle>personality</refentrytitle><manvolnum>2</manvolnum></citerefentry>. Note
942 that a <varname>Personality=</varname>
943 setting in the same unit file has no
944 effect on this condition. A special
946 <varname>native</varname> is mapped to
947 the architecture the system manager
948 itself is compiled for. The test may
949 be negated by prepending an
950 exclamation mark.</para>
952 <para><varname>ConditionVirtualization=</varname>
953 may be used to check whether the
954 system is executed in a virtualized
955 environment and optionally test
956 whether it is a specific
957 implementation. Takes either boolean
958 value to check if being executed in
959 any virtualized environment, or one of
960 <varname>vm</varname> and
961 <varname>container</varname> to test
962 against a generic type of
963 virtualization solution, or one of
964 <varname>qemu</varname>,
965 <varname>kvm</varname>,
966 <varname>vmware</varname>,
967 <varname>microsoft</varname>,
968 <varname>oracle</varname>,
969 <varname>xen</varname>,
970 <varname>bochs</varname>,
971 <varname>chroot</varname>,
972 <varname>uml</varname>,
973 <varname>openvz</varname>,
974 <varname>lxc</varname>,
975 <varname>lxc-libvirt</varname>,
976 <varname>systemd-nspawn</varname> to
977 test against a specific
978 implementation. If multiple
979 virtualization technologies are nested,
980 only the innermost is considered. The
981 test may be negated by prepending an
982 exclamation mark.</para>
984 <para><varname>ConditionHost=</varname>
985 may be used to match against the
986 hostname or machine ID of the
987 host. This either takes a hostname
988 string (optionally with shell style
989 globs) which is tested against the
990 locally set hostname as returned by
991 <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
992 or a machine ID formatted as string
994 <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
995 The test may be negated by prepending
996 an exclamation mark.</para>
998 <para><varname>ConditionKernelCommandLine=</varname>
999 may be used to check whether a
1000 specific kernel command line option is
1001 set (or if prefixed with the
1002 exclamation mark unset). The argument
1003 must either be a single word, or an
1004 assignment (i.e. two words, separated
1005 <literal>=</literal>). In the former
1006 case the kernel command line is
1007 searched for the word appearing as is,
1008 or as left hand side of an
1009 assignment. In the latter case the
1010 exact assignment is looked for with
1011 right and left hand side
1014 <para><varname>ConditionSecurity=</varname>
1015 may be used to check whether the given
1016 security module is enabled on the
1017 system. Currently the recognized values
1018 values are <varname>selinux</varname>,
1019 <varname>apparmor</varname>,
1020 <varname>ima</varname> and
1021 <varname>smack</varname>.
1022 The test may be negated by prepending
1026 <para><varname>ConditionCapability=</varname>
1027 may be used to check whether the given
1028 capability exists in the capability
1029 bounding set of the service manager
1030 (i.e. this does not check whether
1031 capability is actually available in
1032 the permitted or effective sets, see
1033 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1034 for details). Pass a capability name
1035 such as <literal>CAP_MKNOD</literal>,
1036 possibly prefixed with an exclamation
1037 mark to negate the check.</para>
1039 <para><varname>ConditionACPower=</varname>
1040 may be used to check whether the
1041 system has AC power, or is exclusively
1042 battery powered at the time of
1043 activation of the unit. This takes a
1044 boolean argument. If set to
1045 <varname>true</varname>, the condition
1046 will hold only if at least one AC
1047 connector of the system is connected
1048 to a power source, or if no AC
1049 connectors are known. Conversely, if
1050 set to <varname>false</varname>, the
1051 condition will hold only if there is
1052 at least one AC connector known and
1053 all AC connectors are disconnected
1054 from a power source.</para>
1057 <varname>ConditionPathExists=</varname>
1058 a file existence condition is
1059 checked before a unit is started. If
1060 the specified absolute path name does
1061 not exist, the condition will
1062 fail. If the absolute path name passed
1064 <varname>ConditionPathExists=</varname>
1065 is prefixed with an exclamation mark
1066 (<literal>!</literal>), the test is negated, and the unit
1067 is only started if the path does not
1070 <para><varname>ConditionPathExistsGlob=</varname>
1072 <varname>ConditionPathExists=</varname>,
1073 but checks for the existence of at
1074 least one file or directory matching
1075 the specified globbing pattern.</para>
1077 <para><varname>ConditionPathIsDirectory=</varname>
1079 <varname>ConditionPathExists=</varname>
1080 but verifies whether a certain path
1084 <para><varname>ConditionPathIsSymbolicLink=</varname>
1086 <varname>ConditionPathExists=</varname>
1087 but verifies whether a certain path
1088 exists and is a symbolic
1091 <para><varname>ConditionPathIsMountPoint=</varname>
1093 <varname>ConditionPathExists=</varname>
1094 but verifies whether a certain path
1095 exists and is a mount
1098 <para><varname>ConditionPathIsReadWrite=</varname>
1100 <varname>ConditionPathExists=</varname>
1101 but verifies whether the underlying
1102 file system is readable and writable
1106 <para><varname>ConditionDirectoryNotEmpty=</varname>
1108 <varname>ConditionPathExists=</varname>
1109 but verifies whether a certain path
1110 exists and is a non-empty
1113 <para><varname>ConditionFileNotEmpty=</varname>
1115 <varname>ConditionPathExists=</varname>
1116 but verifies whether a certain path
1117 exists and refers to a regular file
1118 with a non-zero size.</para>
1120 <para><varname>ConditionFileIsExecutable=</varname>
1122 <varname>ConditionPathExists=</varname>
1123 but verifies whether a certain path
1124 exists, is a regular file and marked
1128 <varname>ConditionNull=</varname> may
1129 be used to add a constant condition
1130 check value to the unit. It takes a
1131 boolean argument. If set to
1132 <varname>false</varname>, the condition
1133 will always fail, otherwise
1136 <para>If multiple conditions are
1137 specified, the unit will be executed if
1138 all of them apply (i.e. a logical AND
1139 is applied). Condition checks can be
1140 prefixed with a pipe symbol (|) in
1141 which case a condition becomes a
1142 triggering condition. If at least one
1143 triggering condition is defined for a
1144 unit, then the unit will be executed if
1145 at least one of the triggering
1146 conditions apply and all of the
1147 non-triggering conditions. If you
1148 prefix an argument with the pipe
1149 symbol and an exclamation mark, the
1150 pipe symbol must be passed first, the
1151 exclamation second. Except for
1152 <varname>ConditionPathIsSymbolicLink=</varname>,
1153 all path checks follow symlinks. If
1154 any of these options is assigned the
1155 empty string, the list of conditions is
1156 reset completely, all previous
1157 condition settings (of any kind) will
1158 have no effect.</para></listitem>
1162 <term><varname>SourcePath=</varname></term>
1163 <listitem><para>A path to a
1164 configuration file this unit has been
1165 generated from. This is primarily
1166 useful for implementation of generator
1167 tools that convert configuration from
1168 an external configuration file format
1169 into native unit files. Thus
1170 functionality should not be used in
1171 normal units.</para></listitem>
1178 <title>[Install] Section Options</title>
1180 <para>Unit file may include a [Install] section, which
1181 carries installation information for the unit. This
1182 section is not interpreted by
1183 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1184 during runtime. It is used exclusively by the
1185 <command>enable</command> and
1186 <command>disable</command> commands of the
1187 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1188 tool during installation of a unit:</para>
1190 <variablelist class='unit-directives'>
1192 <term><varname>Alias=</varname></term>
1194 <listitem><para>A space-seperated list
1195 of additional names this unit shall be
1196 installed under. The names listed here
1197 must have the same suffix (i.e. type)
1198 as the unit file name. This option may
1199 be specified more than once, in which
1200 case all listed names are used. At
1201 installation time, <command>systemctl
1202 enable</command> will create symlinks
1203 from these names to the unit
1204 filename.</para></listitem>
1208 <term><varname>WantedBy=</varname></term>
1209 <term><varname>RequiredBy=</varname></term>
1211 <listitem><para>This option may be
1212 used more than once, or a
1213 space-separated list of unit names may
1214 be given. A symbolic link is created
1215 in the <filename>.wants/</filename> or
1216 <filename>.requires/</filename>
1217 directory of each of the listed units
1218 when this unit is installed by
1219 <command>systemctl enable</command>.
1220 This has the effect that a dependency
1221 of type <varname>Wants=</varname> or
1222 <varname>Requires=</varname> is added
1223 from the listed unit to the current
1224 unit. The primary result is that the
1225 current unit will be started when the
1226 listed unit is started. See the
1228 <varname>Wants=</varname> and
1229 <varname>Requires=</varname> in the
1230 [Unit] section for details.</para>
1232 <para><command>WantedBy=foo.service</command>
1234 <filename>bar.service</filename> is
1235 mostly equivalent to
1236 <command>Alias=foo.service.wants/bar.service</command>
1237 in the same file. In case of template
1238 units, <command>systemctl enable</command>
1239 must be called with an instance name, and
1240 this instance will be added to the
1241 <filename>.wants/</filename> or
1242 <filename>.requires/</filename> list
1244 E.g. <command>WantedBy=getty.target</command>
1246 <filename>getty@.service</filename>
1247 will result in <command>systemctl
1248 enable getty@tty2.service</command>
1250 <filename>getty.target.wants/getty@tty2.service</filename>
1251 link to <filename>getty@.service</filename>.
1256 <term><varname>Also=</varname></term>
1258 <listitem><para>Additional units to
1259 install/deinstall when this unit is
1260 installed/deinstalled. If the user
1261 requests installation/deinstallation
1262 of a unit with this option configured,
1263 <command>systemctl enable</command>
1264 and <command>systemctl
1265 disable</command> will automatically
1266 install/uninstall units listed in this option as
1269 <para>This option may be used more
1270 than once, or a space-separated list
1271 of unit names may be
1272 given.</para></listitem>
1276 <para>The following specifiers are interpreted in the
1277 Install section: %n, %N, %p, %i, %U, %u, %m, %H, %b, %v.
1278 For their meaning see the next section.
1283 <title>Specifiers</title>
1285 <para>Many settings resolve specifiers which may be
1286 used to write generic unit files referring to runtime
1287 or unit parameters that are replaced when the unit
1288 files are loaded. The following specifiers are
1292 <title>Specifiers available in unit files</title>
1293 <tgroup cols='3' align='left' colsep='1' rowsep='1'>
1294 <colspec colname="spec" />
1295 <colspec colname="mean" />
1296 <colspec colname="detail" />
1299 <entry>Specifier</entry>
1300 <entry>Meaning</entry>
1301 <entry>Details</entry>
1306 <entry><literal>%n</literal></entry>
1307 <entry>Full unit name</entry>
1311 <entry><literal>%N</literal></entry>
1312 <entry>Unescaped full unit name</entry>
1313 <entry>Same as <literal>%n</literal>, but with escaping undone</entry>
1316 <entry><literal>%p</literal></entry>
1317 <entry>Prefix name</entry>
1318 <entry>For instantiated units, this refers to the string before the <literal>@</literal> character of the unit name. For non-instantiated units, this refers to the name of the unit with the type suffix removed.</entry>
1321 <entry><literal>%P</literal></entry>
1322 <entry>Unescaped prefix name</entry>
1323 <entry>Same as <literal>%p</literal>, but with escaping undone</entry>
1326 <entry><literal>%i</literal></entry>
1327 <entry>Instance name</entry>
1328 <entry>For instantiated units: this is the string between the <literal>@</literal> character and the suffix of the unit name.</entry>
1331 <entry><literal>%I</literal></entry>
1332 <entry>Unescaped instance name</entry>
1333 <entry>Same as <literal>%i</literal>, but with escaping undone</entry>
1336 <entry><literal>%f</literal></entry>
1337 <entry>Unescaped filename</entry>
1338 <entry>This is either the unescaped instance name (if applicable) with <filename>/</filename> prepended (if applicable), or the prefix name prepended with <filename>/</filename>.</entry>
1341 <entry><literal>%c</literal></entry>
1342 <entry>Control group path of the unit</entry>
1343 <entry>This path does not include the <filename>/sys/fs/cgroup/systemd/</filename> prefix.</entry>
1346 <entry><literal>%r</literal></entry>
1347 <entry>Control group path of the slice the unit is placed in</entry>
1348 <entry>This usually maps to the parent cgroup path of <literal>%c</literal>.</entry>
1351 <entry><literal>%R</literal></entry>
1352 <entry>Root control group path below which slices and units are placed</entry>
1353 <entry>For system instances, this resolves to <filename>/</filename>, except in containers, where this maps to the container's root control group path.</entry>
1356 <entry><literal>%t</literal></entry>
1357 <entry>Runtime directory</entry>
1358 <entry>This is either <filename>/run</filename> (for the system manager) or the path <literal>$XDG_RUNTIME_DIR</literal> resolves to (for user managers).</entry>
1361 <entry><literal>%u</literal></entry>
1362 <entry>User name</entry>
1363 <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1366 <entry><literal>%U</literal></entry>
1367 <entry>User UID</entry>
1368 <entry>This is the numeric UID of the configured user of the unit, or (if none is set) the user running the systemd user instance. Note that this specifier is not available for units run by the systemd system instance (as opposed to those run by a systemd user instance), unless the user has been configured as a numeric UID in the first place or the configured user is the root user.</entry>
1371 <entry><literal>%h</literal></entry>
1372 <entry>User home directory</entry>
1373 <entry>This is the home directory of the configured user of the unit, or (if none is set) the user running the systemd user instance. Similar to <literal>%U</literal>, this specifier is not available for units run by the systemd system instance, unless the configured user is the root user.</entry>
1376 <entry><literal>%s</literal></entry>
1377 <entry>User shell</entry>
1378 <entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd user instance. Similar to <literal>%U</literal>, this specifier is not available for units run by the systemd system instance, unless the configured user is the root user.</entry>
1381 <entry><literal>%m</literal></entry>
1382 <entry>Machine ID</entry>
1383 <entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
1386 <entry><literal>%b</literal></entry>
1387 <entry>Boot ID</entry>
1388 <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
1391 <entry><literal>%H</literal></entry>
1392 <entry>Host name</entry>
1393 <entry>The hostname of the running system at the point in time the unit configuation is loaded.</entry>
1396 <entry><literal>%v</literal></entry>
1397 <entry>Kernel release</entry>
1398 <entry>Identical to <command>uname -r</command> output</entry>
1401 <entry><literal>%%</literal></entry>
1402 <entry>Single percent sign</entry>
1403 <entry>Use <literal>%%</literal> in place of <literal>%</literal> to specify a single percent sign.</entry>
1411 <title>See Also</title>
1413 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1414 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1415 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1416 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1417 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1418 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1419 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1420 <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1421 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1422 <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1423 <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1424 <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1425 <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1426 <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1427 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1428 <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1429 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1430 <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1431 <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>1</manvolnum></citerefentry>