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">
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="systemd.unit">
27 <title>systemd.unit</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>systemd.unit</refentrytitle>
42 <manvolnum>5</manvolnum>
46 <refname>systemd.unit</refname>
47 <refpurpose>Unit configuration</refpurpose>
51 <para><filename>systemd.service</filename>,
52 <filename>systemd.socket</filename>,
53 <filename>systemd.device</filename>,
54 <filename>systemd.mount</filename>,
55 <filename>systemd.automount</filename>,
56 <filename>systemd.swap</filename>,
57 <filename>systemd.target</filename>,
58 <filename>systemd.path</filename>,
59 <filename>systemd.timer</filename>,
60 <filename>systemd.snapshot</filename></para>
64 <title>Description</title>
66 <para>A unit configuration file encodes information
67 about a service, a socket, a device, a mount point, an
68 automount point, a swap file or partition, a start-up
69 target, a file system path or a timer controlled and
71 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The
72 syntax is inspired by <ulink
73 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
74 Desktop Entry Specification</ulink> <filename>.desktop</filename> files, which are in turn
75 inspired by Microsoft Windows
76 <filename>.ini</filename> files.</para>
78 <para>This man pages lists the common configuration
79 options of all the unit types. These options need to
80 be configured in the [Unit] resp. [Install]
81 section of the unit files.</para>
83 <para>In addition to the generic [Unit] and [Install]
84 sections described here, each unit should have a
85 type-specific section, e.g. [Service] for a service
86 unit. See the respective man pages for more
89 <para>Unit files may contain additional options on top
90 of those listed here. If systemd encounters an unknown
91 option it will write a warning log message but
92 continue loading the unit. If an option is prefixed
93 with <option>X-</option> it is ignored completely by
94 systemd. Applications may use this to include
95 additional information in the unit files.</para>
97 <para>Boolean arguments used in unit files can be
98 written in various formats. For positive settings the
99 strings <option>1</option>, <option>yes</option>,
100 <option>true</option> and <option>on</option> are
101 equivalent. For negative settings the strings
102 <option>0</option>, <option>no</option>,
103 <option>false</option> and <option>off</option> are
106 <para>Time span values encoded in unit files can be
107 written in various formats. A stand-alone number
108 specifies a time in seconds. If suffixed with a time
109 unit, the unit is honored. A concatenation of
110 multiple values with units is supported, in which case
111 the values are added up. Example: "50" refers to 50
112 seconds; "2min 200ms" refers to 2 minutes plus 200
113 milliseconds, i.e. 120200ms. The following time units
114 are understood: s, min, h, d, w, ms, us.</para>
116 <para>Empty lines and lines starting with # or ; are
117 ignored. This may be used for commenting. Lines ending
118 in a backslash are concatenated with the following
119 line while reading and the backslash is replaced by a
120 space character. This may be used to wrap long lines.</para>
122 <para>If a line starts with <option>.include</option>
123 followed by a file name, the specified file will be
124 parsed at this point. Make sure that the file that is
125 included has the appropriate section headers before
126 any directives.</para>
128 <para>Along with a unit file
129 <filename>foo.service</filename> a directory
130 <filename>foo.service.wants/</filename> may exist. All
131 units symlinked from such a directory are implicitly
132 added as dependencies of type
133 <varname>Wanted=</varname> to the unit. This is useful
134 to hook units into the start-up of other units,
135 without having to modify their unit configuration
136 files. For details about the semantics of
137 <varname>Wanted=</varname> see below. The preferred
138 way to create symlinks in the
139 <filename>.wants/</filename> directory of a service is
140 with the <command>enable</command> command of the
141 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
142 tool which reads information from the [Install]
143 section of unit files. (See below.) A similar
144 functionality exists for <varname>Requires=</varname>
145 type dependencies as well, the directory suffix is
146 <filename>.requires/</filename> in this case.</para>
148 <para>Note that while systemd offers a flexible
149 dependency system between units it is recommended to
150 use this functionality only sparsely and instead rely
151 on techniques such as bus-based or socket-based
152 activation which makes dependencies implicit, which
153 both results in a simpler and more flexible
156 <para>Some unit names reflect paths existing in the
157 file system name space. Example: a device unit
158 <filename>dev-sda.device</filename> refers to a device
159 with the device node <filename>/dev/sda</filename> in
160 the file system namespace. If this applies a special
161 way to escape the path name is used, so that the
162 result is usable as part of a file name. Basically,
163 given a path, "/" is replaced by "-", and all
164 unprintable characters and the "-" are replaced by
165 C-style "\x20" escapes. The root directory "/" is
166 encoded as single dash, while otherwise the initial
167 and ending "/" is removed from all paths during
168 transformation. This escaping is reversible.</para>
170 <para>Optionally, units may be instantiated from a
171 template file at runtime. This allows creation of
172 multiple units from a single configuration file. If
173 systemd looks for a unit configuration file it will
174 first search for the literal unit name in the
175 filesystem. If that yields no success and the unit
176 name contains an @ character, systemd will look for a
177 unit template that shares the same name but with the
178 instance string (i.e. the part between the @ character
179 and the suffix) removed. Example: if a service
180 <filename>getty@tty3.service</filename> is requested
181 and no file by that name is found, systemd will look
182 for <filename>getty@.service</filename> and
183 instantiate a service from that configuration file if
186 <para>To refer to the instance string from
187 within the configuration file you may use the special
188 <literal>%i</literal> specifier in many of the
189 configuration options. Other specifiers exist, the
193 <title>Specifiers available in unit files</title>
194 <tgroup cols='3' align='left' colsep='1' rowsep='1'>
195 <colspec colname="spec" />
196 <colspec colname="mean" />
197 <colspec colname="detail" />
200 <entry>Specifier</entry>
201 <entry>Meaning</entry>
202 <entry>Details</entry>
207 <entry><literal>%n</literal></entry>
208 <entry>Full unit name</entry>
212 <entry><literal>%N</literal></entry>
213 <entry>Unescaped full unit name</entry>
217 <entry><literal>%p</literal></entry>
218 <entry>Prefix name</entry>
219 <entry>This refers to the string before the @, i.e. "getty" in the example above, where "tty3" is the instance name.</entry>
222 <entry><literal>%P</literal></entry>
223 <entry>Unescaped prefix name</entry>
227 <entry><literal>%i</literal></entry>
228 <entry>Instance name</entry>
229 <entry>This is the string between the @ character and the suffix.</entry>
232 <entry><literal>%I</literal></entry>
233 <entry>Unescaped instance name</entry>
237 <entry><literal>%f</literal></entry>
238 <entry>Unescaped file name</entry>
239 <entry>This is either the unescaped instance name (if set) with / prepended (if necessary), or the prefix name similarly prepended with /.</entry>
242 <entry><literal>%c</literal></entry>
243 <entry>Control group path of the unit</entry>
247 <entry><literal>%r</literal></entry>
248 <entry>Root control group path of systemd</entry>
252 <entry><literal>%R</literal></entry>
253 <entry>Parent directory of the root control group path of systemd</entry>
257 <entry><literal>%t</literal></entry>
258 <entry>Runtime socket dir</entry>
259 <entry>This is either /run (for the system manager) or $XDG_RUNTIME_DIR (for user managers).</entry>
262 <entry><literal>%u</literal></entry>
263 <entry>User name</entry>
264 <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
267 <entry><literal>%h</literal></entry>
268 <entry>User home directory</entry>
269 <entry>This is the home directory of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
272 <entry><literal>%s</literal></entry>
273 <entry>User shell</entry>
274 <entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
280 <para>If a unit file is empty (i.e. has the file size
281 0) or is symlinked to <filename>/dev/null</filename>
282 its configuration will not be loaded and it appears
283 with a load state of <literal>masked</literal>, and
284 cannot be activated. Use this as an effective way to
285 fully disable a unit, making it impossible to start it
286 even manually.</para>
288 <para>The unit file format is covered by the
290 url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
291 Stability Promise</ulink>.</para>
295 <title>Options</title>
297 <para>Unit file may include a [Unit] section, which
298 carries generic information about the unit that is not
299 dependent on the type of unit:</para>
304 <term><varname>Description=</varname></term>
305 <listitem><para>A free-form string
306 describing the unit. This is intended
307 for use in UIs to show descriptive
308 information along with the unit
309 name.</para></listitem>
313 <term><varname>Documentation=</varname></term>
314 <listitem><para>A space separated list
315 of URIs referencing documentation for
317 configuration. Accepted are only URIs
319 <literal>http://</literal>,
320 <literal>https://</literal>,
321 <literal>file:</literal>,
322 <literal>info:</literal>,
323 <literal>man:</literal>. For more
324 information about the syntax of these
326 <citerefentry><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem>
330 <term><varname>Requires=</varname></term>
332 <listitem><para>Configures requirement
333 dependencies on other units. If this
334 unit gets activated, the units listed
335 here will be activated as well. If one
336 of the other units gets deactivated or
337 its activation fails, this unit will
338 be deactivated. This option may be
339 specified more than once, in which
340 case requirement dependencies for all
341 listed names are created. Note that
342 requirement dependencies do not
343 influence the order in which services
344 are started or stopped. This has to be
345 configured independently with the
346 <varname>After=</varname> or
347 <varname>Before=</varname> options. If
349 <filename>foo.service</filename>
351 <filename>bar.service</filename> as
353 <varname>Requires=</varname> and no
354 ordering is configured with
355 <varname>After=</varname> or
356 <varname>Before=</varname>, then both
357 units will be started simultaneously
358 and without any delay between them if
359 <filename>foo.service</filename> is
360 activated. Often it is a better choice
361 to use <varname>Wants=</varname>
363 <varname>Requires=</varname> in order
364 to achieve a system that is more
365 robust when dealing with failing
366 services.</para></listitem>
370 <term><varname>RequiresOverridable=</varname></term>
372 <listitem><para>Similar to
373 <varname>Requires=</varname>.
374 Dependencies listed in
375 <varname>RequiresOverridable=</varname>
376 which cannot be fulfilled or fail to
377 start are ignored if the startup was
378 explicitly requested by the user. If
379 the start-up was pulled in indirectly
380 by some dependency or automatic
381 start-up of units that is not
382 requested by the user this dependency
383 must be fulfilled and otherwise the
384 transaction fails. Hence, this option
385 may be used to configure dependencies
386 that are normally honored unless the
387 user explicitly starts up the unit, in
388 which case whether they failed or not
389 is irrelevant.</para></listitem>
393 <term><varname>Requisite=</varname></term>
394 <term><varname>RequisiteOverridable=</varname></term>
396 <listitem><para>Similar to
397 <varname>Requires=</varname>
398 resp. <varname>RequiresOverridable=</varname>. However,
399 if a unit listed here is not started
400 already it will not be started and the
402 immediately.</para></listitem>
406 <term><varname>Wants=</varname></term>
408 <listitem><para>A weaker version of
409 <varname>Requires=</varname>. A unit
410 listed in this option will be started
411 if the configuring unit is. However,
412 if the listed unit fails to start up
413 or cannot be added to the transaction
414 this has no impact on the validity of
415 the transaction as a whole. This is
416 the recommended way to hook start-up
417 of one unit to the start-up of another
418 unit. Note that dependencies of this
419 type may also be configured outside of
420 the unit configuration file by
421 adding a symlink to a
422 <filename>.wants/</filename> directory
423 accompanying the unit file. For
424 details see above.</para></listitem>
428 <term><varname>BindsTo=</varname></term>
430 <listitem><para>Configures requirement
431 dependencies, very similar in style to
432 <varname>Requires=</varname>, however
433 in addition to this behaviour it also
434 declares that this unit is stopped
435 when any of the units listed suddenly
436 disappears. Units can suddenly,
437 unexpectedly disappear if a service
438 terminates on its own choice, a device
439 is unplugged or a mount point
440 unmounted without involvement of
441 systemd.</para></listitem>
445 <term><varname>Conflicts=</varname></term>
447 <listitem><para>Configures negative
448 requirement dependencies. If a unit
450 <varname>Conflicts=</varname> setting
451 on another unit, starting the former
452 will stop the latter and vice
453 versa. Note that this setting is
454 independent of and orthogonal to the
455 <varname>After=</varname> and
456 <varname>Before=</varname> ordering
459 <para>If a unit A that conflicts with
460 a unit B is scheduled to be started at
461 the same time as B, the transaction
462 will either fail (in case both are
463 required part of the transaction) or
464 be modified to be fixed (in case one
465 or both jobs are not a required part
466 of the transaction). In the latter
467 case the job that is not the required
468 will be removed, or in case both are
469 not required the unit that conflicts
470 will be started and the unit that is
472 stopped.</para></listitem>
476 <term><varname>Before=</varname></term>
477 <term><varname>After=</varname></term>
479 <listitem><para>Configures ordering
480 dependencies between units. If a unit
481 <filename>foo.service</filename>
483 <option>Before=bar.service</option>
484 and both units are being started,
485 <filename>bar.service</filename>'s
486 start-up is delayed until
487 <filename>foo.service</filename> is
488 started up. Note that this setting is
489 independent of and orthogonal to the
490 requirement dependencies as configured
491 by <varname>Requires=</varname>. It is
492 a common pattern to include a unit
494 <varname>After=</varname> and
495 <varname>Requires=</varname> option in
496 which case the unit listed will be
497 started before the unit that is
498 configured with these options. This
499 option may be specified more than
500 once, in which case ordering
501 dependencies for all listed names are
502 created. <varname>After=</varname> is
504 <varname>Before=</varname>, i.e. while
505 <varname>After=</varname> ensures that
506 the configured unit is started after
507 the listed unit finished starting up,
508 <varname>Before=</varname> ensures the
509 opposite, i.e. that the configured
510 unit is fully started up before the
511 listed unit is started. Note that when
512 two units with an ordering dependency
513 between them are shut down, the
514 inverse of the start-up order is
515 applied. i.e. if a unit is configured
516 with <varname>After=</varname> on
517 another unit, the former is stopped
518 before the latter if both are shut
519 down. If one unit with an ordering
520 dependency on another unit is shut
521 down while the latter is started up,
522 the shut down is ordered before the
523 start-up regardless whether the
524 ordering dependency is actually of
525 type <varname>After=</varname> or
526 <varname>Before=</varname>. If two
527 units have no ordering dependencies
528 between them they are shut down
529 resp. started up simultaneously, and
531 place. </para></listitem>
535 <term><varname>OnFailure=</varname></term>
537 <listitem><para>Lists one or more
538 units that are activated when this
540 '<literal>failed</literal>'
541 state.</para></listitem>
545 <term><varname>PropagatesReloadTo=</varname></term>
546 <term><varname>ReloadPropagatedFrom=</varname></term>
548 <listitem><para>Lists one or more
549 units where reload requests on the
550 unit will be propagated to/on the
551 other unit will be propagated
552 from. Issuing a reload request on a
553 unit will automatically also enqueue a
554 reload request on all units that the
555 reload request shall be propagated to
557 settings.</para></listitem>
561 <term><varname>RequiresMountsFor=</varname></term>
563 <listitem><para>Takes a space
564 separated list of paths. Automatically
565 adds dependencies of type
566 <varname>Requires=</varname> and
567 <varname>After=</varname> for all
568 mount units required to access the
569 specified path.</para></listitem>
573 <term><varname>OnFailureIsolate=</varname></term>
575 <listitem><para>Takes a boolean
576 argument. If <option>true</option> the
578 <varname>OnFailure=</varname> will be
579 enqueued in isolation mode, i.e. all
580 units that are not its dependency will
581 be stopped. If this is set only a
582 single unit may be listed in
583 <varname>OnFailure=</varname>. Defaults
585 <option>false</option>.</para></listitem>
589 <term><varname>IgnoreOnIsolate=</varname></term>
591 <listitem><para>Takes a boolean
592 argument. If <option>true</option>
593 this unit will not be stopped when
594 isolating another unit. Defaults to
595 <option>false</option>.</para></listitem>
599 <term><varname>IgnoreOnSnapshot=</varname></term>
601 <listitem><para>Takes a boolean
602 argument. If <option>true</option>
603 this unit will not be included in
604 snapshots. Defaults to
605 <option>true</option> for device and
606 snapshot units, <option>false</option>
607 for the others.</para></listitem>
611 <term><varname>StopWhenUnneeded=</varname></term>
613 <listitem><para>Takes a boolean
614 argument. If <option>true</option>
615 this unit will be stopped when it is
616 no longer used. Note that in order to
617 minimize the work to be executed,
618 systemd will not stop units by default
619 unless they are conflicting with other
620 units, or the user explicitly
621 requested their shut down. If this
622 option is set, a unit will be
623 automatically cleaned up if no other
624 active unit requires it. Defaults to
625 <option>false</option>.</para></listitem>
629 <term><varname>RefuseManualStart=</varname></term>
630 <term><varname>RefuseManualStop=</varname></term>
632 <listitem><para>Takes a boolean
633 argument. If <option>true</option>
634 this unit can only be activated
635 (resp. deactivated) indirectly. In
636 this case explicit start-up
637 (resp. termination) requested by the
638 user is denied, however if it is
639 started (resp. stopped) as a
640 dependency of another unit, start-up
641 (resp. termination) will succeed. This
642 is mostly a safety feature to ensure
643 that the user does not accidentally
644 activate units that are not intended
645 to be activated explicitly, and not
646 accidentally deactivate units that are
647 not intended to be deactivated.
648 These options default to
649 <option>false</option>.</para></listitem>
653 <term><varname>AllowIsolate=</varname></term>
655 <listitem><para>Takes a boolean
656 argument. If <option>true</option>
657 this unit may be used with the
658 <command>systemctl isolate</command>
659 command. Otherwise this will be
660 refused. It probably is a good idea to
661 leave this disabled except for target
662 units that shall be used similar to
663 runlevels in SysV init systems, just
664 as a precaution to avoid unusable
665 system states. This option defaults to
666 <option>false</option>.</para></listitem>
670 <term><varname>DefaultDependencies=</varname></term>
672 <listitem><para>Takes a boolean
673 argument. If <option>true</option>
674 (the default), a few default
675 dependencies will implicitly be
676 created for the unit. The actual
677 dependencies created depend on the
678 unit type. For example, for service
679 units, these dependencies ensure that
680 the service is started only after
681 basic system initialization is
682 completed and is properly terminated on
683 system shutdown. See the respective
684 man pages for details. Generally, only
685 services involved with early boot or
686 late shutdown should set this option
687 to <option>false</option>. It is
688 highly recommended to leave this
689 option enabled for the majority of
690 common units. If set to
691 <option>false</option> this option
692 does not disable all implicit
693 dependencies, just non-essential
694 ones.</para></listitem>
698 <term><varname>JobTimeoutSec=</varname></term>
700 <listitem><para>When clients are
701 waiting for a job of this unit to
702 complete, time out after the specified
703 time. If this time limit is reached
704 the job will be cancelled, the unit
705 however will not change state or even
706 enter the '<literal>failed</literal>'
707 mode. This value defaults to 0 (job
708 timeouts disabled), except for device
709 units. NB: this timeout is independent
710 from any unit-specific timeout (for
711 example, the timeout set with
712 <varname>Timeout=</varname> in service
713 units) as the job timeout has no
714 effect on the unit itself, only on the
715 job that might be pending for it. Or
716 in other words: unit-specific timeouts
717 are useful to abort unit state
718 changes, and revert them. The job
719 timeout set with this option however
720 is useful to abort only the job
721 waiting for the unit state to
722 change.</para></listitem>
726 <term><varname>ConditionPathExists=</varname></term>
727 <term><varname>ConditionPathExistsGlob=</varname></term>
728 <term><varname>ConditionPathIsDirectory=</varname></term>
729 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
730 <term><varname>ConditionPathIsMountPoint=</varname></term>
731 <term><varname>ConditionPathIsReadWrite=</varname></term>
732 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
733 <term><varname>ConditionFileIsExecutable=</varname></term>
734 <term><varname>ConditionKernelCommandLine=</varname></term>
735 <term><varname>ConditionVirtualization=</varname></term>
736 <term><varname>ConditionSecurity=</varname></term>
737 <term><varname>ConditionCapability=</varname></term>
738 <term><varname>ConditionNull=</varname></term>
740 <listitem><para>Before starting a unit
741 verify that the specified condition is
743 <varname>ConditionPathExists=</varname>
744 a file existence condition can be
745 checked before a unit is started. If
746 the specified absolute path name does
747 not exist, startup of a unit will not
748 actually happen, however the unit is
749 still useful for ordering purposes in
750 this case. The condition is checked at
751 the time the queued start job is to be
752 executed. If the absolute path name
754 <varname>ConditionPathExists=</varname>
755 is prefixed with an exclamation mark
756 (!), the test is negated, and the unit
757 is only started if the path does not
759 <varname>ConditionPathExistsGlob=</varname>
760 works in a similar way, but checks for
761 the existence of at least one file or
762 directory matching the specified
764 pattern. <varname>ConditionPathIsDirectory=</varname>
766 <varname>ConditionPathExists=</varname>
767 but verifies whether a certain path
769 directory. <varname>ConditionPathIsSymbolicLink=</varname>
771 <varname>ConditionPathExists=</varname>
772 but verifies whether a certain path
773 exists and is a symbolic
774 link. <varname>ConditionPathIsMountPoint=</varname>
776 <varname>ConditionPathExists=</varname>
777 but verifies whether a certain path
778 exists and is a mount
779 point. <varname>ConditionPathIsReadWrite=</varname>
781 <varname>ConditionPathExists=</varname>
782 but verifies whether the underlying
783 file system is read and writable
785 read-only). <varname>ConditionFileIsExecutable=</varname>
787 <varname>ConditionPathExists=</varname>
788 but verifies whether a certain path
789 exists, is a regular file and marked
791 <varname>ConditionDirectoryNotEmpty=</varname>
793 <varname>ConditionPathExists=</varname>
794 but verifies whether a certain path
795 exists and is a non-empty
797 <varname>ConditionKernelCommandLine=</varname>
798 may be used to check whether a
799 specific kernel command line option is
800 set (or if prefixed with the
801 exclamation mark unset). The argument
802 must either be a single word, or an
803 assignment (i.e. two words, separated
804 by the equality sign). In the former
805 case the kernel command line is
806 searched for the word appearing as is,
807 or as left hand side of an
808 assignment. In the latter case the
809 exact assignment is looked for with
810 right and left hand side
811 matching. <varname>ConditionVirtualization=</varname>
812 may be used to check whether the
813 system is executed in a virtualized
814 environment and optionally test
815 whether it is a specific
816 implementation. Takes either boolean
817 value to check if being executed in
818 any virtualized environment, or one of
819 <varname>vm</varname> and
820 <varname>container</varname> to test
821 against a specific type of
822 virtualization solution, or one of
823 <varname>qemu</varname>,
824 <varname>kvm</varname>,
825 <varname>vmware</varname>,
826 <varname>microsoft</varname>,
827 <varname>oracle</varname>,
828 <varname>xen</varname>,
829 <varname>bochs</varname>,
830 <varname>chroot</varname>,
831 <varname>openvz</varname>,
832 <varname>lxc</varname>,
833 <varname>lxc-libvirt</varname>,
834 <varname>systemd-nspawn</varname> to
835 test against a specific
836 implementation. If multiple
837 virtualization technologies are nested
838 only the innermost is considered. The
839 test may be negated by prepending an
841 <varname>ConditionSecurity=</varname>
842 may be used to check whether the given
843 security module is enabled on the
844 system. Currently the only recognized
845 value is <varname>selinux</varname>.
846 The test may be negated by prepending
848 mark. <varname>ConditionCapability=</varname>
849 may be used to check whether the given
850 capability exists in the capability
851 bounding set of the service manager
852 (i.e. this does not check whether
853 capability is actually available in
854 the permitted or effective sets, see
855 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
856 for details). Pass a capability name
857 such as <literal>CAP_MKNOD</literal>,
858 possibly prefixed with an exclamation
859 mark to negate the check. Finally,
860 <varname>ConditionNull=</varname> may
861 be used to add a constant condition
862 check value to the unit. It takes a
863 boolean argument. If set to
864 <varname>false</varname> the condition
865 will always fail, otherwise
866 succeed. If multiple conditions are
867 specified the unit will be executed if
868 all of them apply (i.e. a logical AND
869 is applied). Condition checks can be
870 prefixed with a pipe symbol (|) in
871 which case a condition becomes a
872 triggering condition. If at least one
873 triggering condition is defined for a
874 unit then the unit will be executed if
875 at least one of the triggering
876 conditions apply and all of the
877 non-triggering conditions. If you
878 prefix an argument with the pipe
879 symbol and an exclamation mark the
880 pipe symbol must be passed first, the
881 exclamation second. Except for
882 <varname>ConditionPathIsSymbolicLink=</varname>,
883 all path checks follow
884 symlinks.</para></listitem>
888 <term><varname>SourcePath=</varname></term>
889 <listitem><para>A path to a
890 configuration file this unit has been
891 generated from. This is primarily
892 useful for implementation of generator
893 tools that convert configuration from
894 an external configuration file format
895 into native unit files. Thus
896 functionality should not be used in
897 normal units.</para></listitem>
901 <para>Unit file may include a [Install] section, which
902 carries installation information for the unit. This
903 section is not interpreted by
904 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
905 during runtime. It is used exclusively by the
906 <command>enable</command> and
907 <command>disable</command> commands of the
908 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
909 tool during installation of a unit:</para>
913 <term><varname>Alias=</varname></term>
915 <listitem><para>Additional names this
916 unit shall be installed under. The
917 names listed here must have the same
918 suffix (i.e. type) as the unit file
919 name. This option may be specified
920 more than once, in which case all
921 listed names are used. At installation
923 <command>systemctl enable</command>
924 will create symlinks from these names
925 to the unit file name.</para></listitem>
929 <term><varname>WantedBy=</varname></term>
930 <term><varname>RequiredBy=</varname></term>
932 <listitem><para>Installs a symlink in
933 the <filename>.wants/</filename>
934 resp. <filename>.requires/</filename>
935 subdirectory for a unit. This has the
936 effect that when the listed unit name
937 is activated the unit listing it is
939 too. <command>WantedBy=foo.service</command>
941 <filename>bar.service</filename> is
943 <command>Alias=foo.service.wants/bar.service</command>
944 in the same file.</para></listitem>
948 <term><varname>Also=</varname></term>
950 <listitem><para>Additional units to
951 install when this unit is
952 installed. If the user requests
953 installation of a unit with this
955 <command>systemctl enable</command>
956 will automatically install units
957 listed in this option as
958 well.</para></listitem>
965 <title>See Also</title>
967 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
968 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
969 <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
970 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
971 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
972 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
973 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
974 <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
975 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
976 <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
977 <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
978 <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
979 <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
980 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>