chiark / gitweb /
man: explicitly say when multiple units can be specified
[elogind.git] / man / systemd.unit.xml
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" >
5 %entities;
6 ]>
7
8 <!--
9   This file is part of systemd.
10
11   Copyright 2010 Lennart Poettering
12
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14   under the terms of the GNU Lesser General Public License as published by
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16   (at your option) any later version.
17
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21   Lesser General Public License for more details.
22
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/>.
25 -->
26
27 <refentry id="systemd.unit">
28
29         <refentryinfo>
30                 <title>systemd.unit</title>
31                 <productname>systemd</productname>
32
33                 <authorgroup>
34                         <author>
35                                 <contrib>Developer</contrib>
36                                 <firstname>Lennart</firstname>
37                                 <surname>Poettering</surname>
38                                 <email>lennart@poettering.net</email>
39                         </author>
40                 </authorgroup>
41         </refentryinfo>
42
43         <refmeta>
44                 <refentrytitle>systemd.unit</refentrytitle>
45                 <manvolnum>5</manvolnum>
46         </refmeta>
47
48         <refnamediv>
49                 <refname>systemd.unit</refname>
50                 <refpurpose>Unit configuration</refpurpose>
51         </refnamediv>
52
53         <refsynopsisdiv>
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>
66
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>
72
73                 <para><literallayout><filename>$HOME/.config/systemd/user/*</filename>
74 <filename>/etc/systemd/user/*</filename>
75 <filename>/run/systemd/user/*</filename>
76 <filename>/usr/lib/systemd/user/*</filename>
77 <filename>...</filename>
78                 </literallayout></para>
79         </refsynopsisdiv>
80
81         <refsect1>
82                 <title>Description</title>
83
84                 <para>A unit configuration file encodes information
85                 about a service, a socket, a device, a mount point, an
86                 automount point, a swap file or partition, a start-up
87                 target, a watched file system path, a timer controlled
88                 and supervised by
89                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
90                 a temporary system state snapshot, a resource
91                 management slice or a group of externally created
92                 processes. The syntax is inspired by <ulink
93                 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
94                 Desktop Entry Specification</ulink>
95                 <filename>.desktop</filename> files, which are in turn
96                 inspired by Microsoft Windows
97                 <filename>.ini</filename> files.</para>
98
99                 <para>This man page lists the common configuration
100                 options of all the unit types. These options need to
101                 be configured in the [Unit] or [Install]
102                 sections of the unit files.</para>
103
104                 <para>In addition to the generic [Unit] and [Install]
105                 sections described here, each unit may have a
106                 type-specific section, e.g. [Service] for a service
107                 unit. See the respective man pages for more
108                 information:
109                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
110                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
111                 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
112                 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
113                 <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
114                 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
115                 <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
116                 <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
117                 <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
118                 <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
119                 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
120                 <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
121                 </para>
122
123                 <para>Unit files are loaded from a set of paths
124                 determined during compilation, described in the next section.
125                 </para>
126
127                 <para>Unit files may contain additional options on top
128                 of those listed here. If systemd encounters an unknown
129                 option, it will write a warning log message but
130                 continue loading the unit. If an option is prefixed
131                 with <option>X-</option>, it is ignored completely by
132                 systemd. Applications may use this to include
133                 additional information in the unit files.</para>
134
135                 <para>Boolean arguments used in unit files can be
136                 written in various formats. For positive settings the
137                 strings <option>1</option>, <option>yes</option>,
138                 <option>true</option> and <option>on</option> are
139                 equivalent. For negative settings, the strings
140                 <option>0</option>, <option>no</option>,
141                 <option>false</option> and <option>off</option> are
142                 equivalent.</para>
143
144                 <para>Time span values encoded in unit files can be
145                 written in various formats. A stand-alone number
146                 specifies a time in seconds. If suffixed with a time
147                 unit, the unit is honored. A concatenation of multiple
148                 values with units is supported, in which case the
149                 values are added up. Example: "50" refers to 50
150                 seconds; "2min 200ms" refers to 2 minutes plus 200
151                 milliseconds, i.e. 120200ms. The following time units
152                 are understood: s, min, h, d, w, ms, us. For details
153                 see
154                 <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
155
156                 <para>Empty lines and lines starting with # or ; are
157                 ignored. This may be used for commenting. Lines ending
158                 in a backslash are concatenated with the following
159                 line while reading and the backslash is replaced by a
160                 space character. This may be used to wrap long lines.</para>
161
162                 <para>Along with a unit file
163                 <filename>foo.service</filename>, the directory
164                 <filename>foo.service.wants/</filename> may exist. All
165                 unit files symlinked from such a directory are
166                 implicitly added as dependencies of type
167                 <varname>Wanted=</varname> to the unit. This is useful
168                 to hook units into the start-up of other units,
169                 without having to modify their unit files. For details
170                 about the semantics of <varname>Wanted=</varname>, see
171                 below. The preferred way to create symlinks in the
172                 <filename>.wants/</filename> directory of a unit file
173                 is with the <command>enable</command> command of the
174                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
175                 tool which reads information from the [Install]
176                 section of unit files (see below). A similar
177                 functionality exists for <varname>Requires=</varname>
178                 type dependencies as well, the directory suffix is
179                 <filename>.requires/</filename> in this case.</para>
180
181                 <para>Along with a unit file
182                 <filename>foo.service</filename>, a directory
183                 <filename>foo.service.d/</filename> may exist. All
184                 files with the suffix <literal>.conf</literal> from
185                 this directory will be parsed after the file itself is
186                 parsed. This is useful to alter or add configuration
187                 settings to a unit, without having to modify their
188                 unit files. Make sure that the file that is included
189                 has the appropriate section headers before any
190                 directive.</para>
191
192                 <para>If a line starts with <option>.include</option>
193                 followed by a filename, the specified file will be
194                 parsed at this point. Make sure that the file that is
195                 included has the appropriate section headers before
196                 any directives.</para>
197
198                 <para>Note that while systemd offers a flexible
199                 dependency system between units it is recommended to
200                 use this functionality only sparingly and instead rely
201                 on techniques such as bus-based or socket-based
202                 activation which make dependencies implicit, resulting
203                 in a both simpler and more flexible system.</para>
204
205                 <para>Some unit names reflect paths existing in the
206                 file system namespace. Example: a device unit
207                 <filename>dev-sda.device</filename> refers to a device
208                 with the device node <filename noindex='true'>/dev/sda</filename> in
209                 the file system namespace. If this applies, a special
210                 way to escape the path name is used, so that the
211                 result is usable as part of a filename. Basically,
212                 given a path, "/" is replaced by "-", and all
213                 unprintable characters and the "-" are replaced by
214                 C-style "\x20" escapes. The root directory "/" is
215                 encoded as single dash, while otherwise the initial
216                 and ending "/" is removed from all paths during
217                 transformation. This escaping is reversible.</para>
218
219                 <para>Optionally, units may be instantiated from a
220                 template file at runtime. This allows creation of
221                 multiple units from a single configuration file. If
222                 systemd looks for a unit configuration file, it will
223                 first search for the literal unit name in the
224                 filesystem. If that yields no success and the unit
225                 name contains an <literal>@</literal> character, systemd will look for a
226                 unit template that shares the same name but with the
227                 instance string (i.e. the part between the <literal>@</literal> character
228                 and the suffix) removed. Example: if a service
229                 <filename>getty@tty3.service</filename> is requested
230                 and no file by that name is found, systemd will look
231                 for <filename>getty@.service</filename> and
232                 instantiate a service from that configuration file if
233                 it is found.</para>
234
235                 <para>To refer to the instance string from
236                 within the configuration file you may use the special
237                 <literal>%i</literal> specifier in many of the
238                 configuration options. See below for details.</para>
239
240                 <para>If a unit file is empty (i.e. has the file size
241                 0) or is symlinked to <filename>/dev/null</filename>,
242                 its configuration will not be loaded and it appears
243                 with a load state of <literal>masked</literal>, and
244                 cannot be activated. Use this as an effective way to
245                 fully disable a unit, making it impossible to start it
246                 even manually.</para>
247
248                 <para>The unit file format is covered by the
249                 <ulink
250                 url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
251                 Stability Promise</ulink>.</para>
252
253         </refsect1>
254
255         <refsect1>
256                 <title>Unit Load Path</title>
257
258                 <para>Unit files are loaded from a set of paths
259                 determined during compilation, described in the two
260                 tables below. Unit files found in directories listed
261                 earlier override files with the same name in
262                 directories lower in the list.</para>
263
264                 <para>When systemd is running in user mode
265                 (<option>--user</option>) and the variable
266                 <varname>$SYSTEMD_UNIT_PATH</varname> is set, this
267                 contents of this variable overrides the unit load
268                 path.
269                 </para>
270
271                 <table>
272                   <title>
273                     Load path when running in system mode (<option>--system</option>).
274                   </title>
275
276                   <tgroup cols='2'>
277                     <colspec colname='path' />
278                     <colspec colname='expl' />
279                     <thead>
280                       <row>
281                         <entry>Path</entry>
282                         <entry>Description</entry>
283                       </row>
284                     </thead>
285                     <tbody>
286                       <row>
287                         <entry><filename>/etc/systemd/system</filename></entry>
288                         <entry>Local configuration</entry>
289                       </row>
290                       <row>
291                         <entry><filename>/run/systemd/system</filename></entry>
292                         <entry>Runtime units</entry>
293                       </row>
294                       <row>
295                         <entry><filename>/usr/lib/systemd/system</filename></entry>
296                         <entry>Units of installed packages</entry>
297                       </row>
298                     </tbody>
299                   </tgroup>
300                 </table>
301
302                 <table>
303                   <title>
304                     Load path when running in user mode (<option>--user</option>).
305                   </title>
306
307                   <tgroup cols='2'>
308                     <colspec colname='path' />
309                     <colspec colname='expl' />
310                     <thead>
311                       <row>
312                         <entry>Path</entry>
313                         <entry>Description</entry>
314                       </row>
315                     </thead>
316                     <tbody>
317                       <row>
318                         <entry><filename>$HOME/.config/systemd/user</filename></entry>
319                         <entry>User configuration</entry>
320                       </row>
321                       <row>
322                         <entry><filename>/etc/systemd/user</filename></entry>
323                         <entry>Local configuration</entry>
324                       </row>
325                       <row>
326                         <entry><filename>/run/systemd/user</filename></entry>
327                         <entry>Runtime units</entry>
328                       </row>
329                       <row>
330                         <entry><filename>/usr/lib/systemd/user</filename></entry>
331                         <entry>Units of installed packages</entry>
332                       </row>
333                     </tbody>
334                   </tgroup>
335                 </table>
336
337                 <para>Additional units might be loaded into systemd
338                 ("linked") from directories not on the unit load
339                 path. See the <command>link</command> command for
340                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. Also,
341                 some units are dynamically created via generators
342                 <ulink
343                 url="http://www.freedesktop.org/wiki/Software/systemd/Generators/">Generators</ulink>.
344                 </para>
345         </refsect1>
346
347         <refsect1>
348                 <title>Options</title>
349
350                 <para>Unit file may include a [Unit] section, which
351                 carries generic information about the unit that is not
352                 dependent on the type of unit:</para>
353
354                 <variablelist class='unit-directives'>
355
356                         <varlistentry>
357                                 <term><varname>Description=</varname></term>
358                                 <listitem><para>A free-form string
359                                 describing the unit. This is intended
360                                 for use in UIs to show descriptive
361                                 information along with the unit
362                                 name. The description should contain a name
363                                 that means something to the end user.
364                                 <literal>Apache2 Web Server</literal> is a good
365                                 example. Bad examples are
366                                 <literal>high-performance light-weight HTTP
367                                 server</literal> (too generic) or
368                                 <literal>Apache2</literal> (too specific and
369                                 meaningless for people who do not know
370                                 Apache).</para></listitem>
371                         </varlistentry>
372
373                         <varlistentry>
374                                 <term><varname>Documentation=</varname></term>
375                                 <listitem><para>A space-separated list
376                                 of URIs referencing documentation for
377                                 this unit or its
378                                 configuration. Accepted are only URIs
379                                 of the types
380                                 <literal>http://</literal>,
381                                 <literal>https://</literal>,
382                                 <literal>file:</literal>,
383                                 <literal>info:</literal>,
384                                 <literal>man:</literal>. For more
385                                 information about the syntax of these
386                                 URIs, see
387                                 <citerefentry><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
388                                 URIs should be listed in order of
389                                 relevance, starting with the most
390                                 relevant. It is a good idea to first
391                                 reference documentation that explains
392                                 what the unit's purpose is, followed
393                                 by how it is configured, followed by
394                                 any other related documentation. This
395                                 option may be specified more than once
396                                 in which case the specified list of
397                                 URIs is merged. If the empty string is
398                                 assigned to this option, the list is
399                                 reset and all prior assignments will
400                                 have no effect.</para></listitem>
401                         </varlistentry>
402
403                         <varlistentry>
404                                 <term><varname>Requires=</varname></term>
405
406                                 <listitem><para>Configures requirement
407                                 dependencies on other units. If this
408                                 unit gets activated, the units listed
409                                 here will be activated as well. If one
410                                 of the other units gets deactivated or
411                                 its activation fails, this unit will
412                                 be deactivated. This option may be
413                                 specified more than once or multiple
414                                 space-separated units may be specified
415                                 in one option in which case
416                                 requirement dependencies for all
417                                 listed names will be created. Note
418                                 that requirement dependencies do not
419                                 influence the order in which services
420                                 are started or stopped. This has to be
421                                 configured independently with the
422                                 <varname>After=</varname> or
423                                 <varname>Before=</varname> options. If
424                                 a unit
425                                 <filename>foo.service</filename>
426                                 requires a unit
427                                 <filename>bar.service</filename> as
428                                 configured with
429                                 <varname>Requires=</varname> and no
430                                 ordering is configured with
431                                 <varname>After=</varname> or
432                                 <varname>Before=</varname>, then both
433                                 units will be started simultaneously
434                                 and without any delay between them if
435                                 <filename>foo.service</filename> is
436                                 activated. Often it is a better choice
437                                 to use <varname>Wants=</varname>
438                                 instead of
439                                 <varname>Requires=</varname> in order
440                                 to achieve a system that is more
441                                 robust when dealing with failing
442                                 services.</para>
443
444                                 <para>Note that dependencies of this
445                                 type may also be configured outside of
446                                 the unit configuration file by
447                                 adding a symlink to a
448                                 <filename>.requires/</filename> directory
449                                 accompanying the unit file. For
450                                 details see above.</para></listitem>
451                         </varlistentry>
452
453                         <varlistentry>
454                                 <term><varname>RequiresOverridable=</varname></term>
455
456                                 <listitem><para>Similar to
457                                 <varname>Requires=</varname>.
458                                 Dependencies listed in
459                                 <varname>RequiresOverridable=</varname>
460                                 which cannot be fulfilled or fail to
461                                 start are ignored if the startup was
462                                 explicitly requested by the user. If
463                                 the start-up was pulled in indirectly
464                                 by some dependency or automatic
465                                 start-up of units that is not
466                                 requested by the user, this dependency
467                                 must be fulfilled and otherwise the
468                                 transaction fails. Hence, this option
469                                 may be used to configure dependencies
470                                 that are normally honored unless the
471                                 user explicitly starts up the unit, in
472                                 which case whether they failed or not
473                                 is irrelevant.</para></listitem>
474
475                         </varlistentry>
476                         <varlistentry>
477                                 <term><varname>Requisite=</varname></term>
478                                 <term><varname>RequisiteOverridable=</varname></term>
479
480                                 <listitem><para>Similar to
481                                 <varname>Requires=</varname> and
482                                 <varname>RequiresOverridable=</varname>,
483                                 respectively. However, if the units
484                                 listed here are not started already
485                                 they will not be started and the
486                                 transaction will fail immediately.
487                                 </para></listitem>
488                         </varlistentry>
489
490                         <varlistentry>
491                                 <term><varname>Wants=</varname></term>
492
493                                 <listitem><para>A weaker version of
494                                 <varname>Requires=</varname>. Units
495                                 listed in this option will be started
496                                 if the configuring unit is. However,
497                                 if the listed units fail to start
498                                 or cannot be added to the transaction
499                                 this has no impact on the validity of
500                                 the transaction as a whole. This is
501                                 the recommended way to hook start-up
502                                 of one unit to the start-up of another
503                                 unit.</para>
504
505                                 <para>Note that dependencies of this
506                                 type may also be configured outside of
507                                 the unit configuration file by adding
508                                 symlinks to a
509                                 <filename>.wants/</filename> directory
510                                 accompanying the unit file. For
511                                 details see above.</para></listitem>
512                         </varlistentry>
513
514                         <varlistentry>
515                                 <term><varname>BindsTo=</varname></term>
516
517                                 <listitem><para>Configures requirement
518                                 dependencies, very similar in style to
519                                 <varname>Requires=</varname>, however
520                                 in addition to this behavior it also
521                                 declares that this unit is stopped
522                                 when any of the units listed suddenly
523                                 disappears. Units can suddenly,
524                                 unexpectedly disappear if a service
525                                 terminates on its own choice, a device
526                                 is unplugged or a mount point
527                                 unmounted without involvement of
528                                 systemd.</para></listitem>
529                         </varlistentry>
530
531                         <varlistentry>
532                                 <term><varname>PartOf=</varname></term>
533
534                                 <listitem><para>Configures dependencies
535                                 similar to <varname>Requires=</varname>,
536                                 but limited to stopping and restarting
537                                 of units. When systemd stops or restarts
538                                 the units listed here, the action is
539                                 propagated to this unit.
540                                 Note that this is a one way dependency —
541                                 changes to this unit do not affect the
542                                 listed units.
543                                 </para></listitem>
544                         </varlistentry>
545
546                         <varlistentry>
547                                 <term><varname>Conflicts=</varname></term>
548
549                                 <listitem><para>A space-separated list
550                                 of unit names. Configures negative
551                                 requirement dependencies. If a unit
552                                 has a <varname>Conflicts=</varname>
553                                 setting on another unit, starting the
554                                 former will stop the latter and vice
555                                 versa. Note that this setting is
556                                 independent of and orthogonal to the
557                                 <varname>After=</varname> and
558                                 <varname>Before=</varname> ordering
559                                 dependencies.</para>
560
561                                 <para>If a unit A that conflicts with
562                                 a unit B is scheduled to be started at
563                                 the same time as B, the transaction
564                                 will either fail (in case both are
565                                 required part of the transaction) or
566                                 be modified to be fixed (in case one
567                                 or both jobs are not a required part
568                                 of the transaction). In the latter
569                                 case the job that is not the required
570                                 will be removed, or in case both are
571                                 not required the unit that conflicts
572                                 will be started and the unit that is
573                                 conflicted is
574                                 stopped.</para></listitem>
575                         </varlistentry>
576
577                         <varlistentry>
578                                 <term><varname>Before=</varname></term>
579                                 <term><varname>After=</varname></term>
580
581                                 <listitem><para>A space-separated list
582                                 of unit names. Configures ordering
583                                 dependencies between units. If a unit
584                                 <filename>foo.service</filename>
585                                 contains a setting
586                                 <option>Before=bar.service</option>
587                                 and both units are being started,
588                                 <filename>bar.service</filename>'s
589                                 start-up is delayed until
590                                 <filename>foo.service</filename> is
591                                 started up. Note that this setting is
592                                 independent of and orthogonal to the
593                                 requirement dependencies as configured
594                                 by <varname>Requires=</varname>. It is
595                                 a common pattern to include a unit
596                                 name in both the
597                                 <varname>After=</varname> and
598                                 <varname>Requires=</varname> option in
599                                 which case the unit listed will be
600                                 started before the unit that is
601                                 configured with these options. This
602                                 option may be specified more than
603                                 once, in which case ordering
604                                 dependencies for all listed names are
605                                 created. <varname>After=</varname> is
606                                 the inverse of
607                                 <varname>Before=</varname>, i.e. while
608                                 <varname>After=</varname> ensures that
609                                 the configured unit is started after
610                                 the listed unit finished starting up,
611                                 <varname>Before=</varname> ensures the
612                                 opposite, i.e.  that the configured
613                                 unit is fully started up before the
614                                 listed unit is started. Note that when
615                                 two units with an ordering dependency
616                                 between them are shut down, the
617                                 inverse of the start-up order is
618                                 applied. i.e. if a unit is configured
619                                 with <varname>After=</varname> on
620                                 another unit, the former is stopped
621                                 before the latter if both are shut
622                                 down. If one unit with an ordering
623                                 dependency on another unit is shut
624                                 down while the latter is started up,
625                                 the shut down is ordered before the
626                                 start-up regardless whether the
627                                 ordering dependency is actually of
628                                 type <varname>After=</varname> or
629                                 <varname>Before=</varname>. If two
630                                 units have no ordering dependencies
631                                 between them, they are shut down or
632                                 started up simultaneously, and no
633                                 ordering takes
634                                 place. </para></listitem>
635                         </varlistentry>
636
637                         <varlistentry>
638                                 <term><varname>OnFailure=</varname></term>
639
640                                 <listitem><para>A space-separated list
641                                 of one or more units that are
642                                 activated when this unit enters the
643                                 <literal>failed</literal>
644                                 state.</para></listitem>
645                         </varlistentry>
646
647                         <varlistentry>
648                                 <term><varname>PropagatesReloadTo=</varname></term>
649                                 <term><varname>ReloadPropagatedFrom=</varname></term>
650
651                                 <listitem><para>A space-separated list
652                                 of one or more units where reload
653                                 requests on this unit will be
654                                 propagated to, or reload requests on
655                                 the other unit will be propagated to
656                                 this unit, respectively. Issuing a
657                                 reload request on a unit will
658                                 automatically also enqueue a reload
659                                 request on all units that the reload
660                                 request shall be propagated to via
661                                 these two settings.</para></listitem>
662                         </varlistentry>
663
664                         <varlistentry>
665                                 <term><varname>JoinsNamespaceOf=</varname></term>
666
667                                 <listitem><para>For units that start
668                                 processes (such as service units),
669                                 lists one or more other units whose
670                                 network and/or temporary file
671                                 namespace to join. This only applies
672                                 to unit types which support the
673                                 <varname>PrivateNetwork=</varname> and
674                                 <varname>PrivateTmp=</varname>
675                                 directives (see
676                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
677                                 for details). If a unit that has this
678                                 setting set is started its processes
679                                 will see the same
680                                 <filename>/tmp</filename>,
681                                 <filename>/tmp/var</filename> and
682                                 network namespace as one listed unit
683                                 that is started. If multiple listed
684                                 units are already started it is not
685                                 defined which namespace is
686                                 joined. Note that this setting only
687                                 has an effect if
688                                 <varname>PrivateNetwork=</varname>
689                                 and/or <varname>PrivateTmp=</varname>
690                                 is enabled for both the unit that
691                                 joins the namespace and the unit whose
692                                 namespace is joined.</para></listitem>
693                         </varlistentry>
694
695                         <varlistentry>
696                                 <term><varname>RequiresMountsFor=</varname></term>
697
698                                 <listitem><para>Takes a space-separated
699                                 list of absolute paths. Automatically
700                                 adds dependencies of type
701                                 <varname>Requires=</varname> and
702                                 <varname>After=</varname> for all
703                                 mount units required to access the
704                                 specified path.</para></listitem>
705                         </varlistentry>
706
707                         <varlistentry>
708                                 <term><varname>OnFailureJobMode=</varname></term>
709
710                                 <listitem><para>Takes a value of
711                                 <literal>fail</literal>,
712                                 <literal>replace</literal>,
713                                 <literal>replace-irreversibly</literal>,
714                                 <literal>isolate</literal>,
715                                 <literal>flush</literal>,
716                                 <literal>ignore-dependencies</literal>
717                                 or
718                                 <literal>ignore-requirements</literal>. Defaults
719                                 to
720                                 <literal>replace</literal>. Specifies
721                                 how the units listed in
722                                 <varname>OnFailure=</varname> will be
723                                 enqueued. See
724                                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
725                                 <option>--job-mode=</option> option
726                                 for details on the possible values. If
727                                 this is set to
728                                 <literal>isolate</literal>, only a
729                                 single unit may be listed in
730                                 <varname>OnFailure=</varname>..</para></listitem>
731                         </varlistentry>
732
733                         <varlistentry>
734                                 <term><varname>IgnoreOnIsolate=</varname></term>
735
736                                 <listitem><para>Takes a boolean
737                                 argument. If <option>true</option>,
738                                 this unit will not be stopped when
739                                 isolating another unit. Defaults to
740                                 <option>false</option>.</para></listitem>
741                         </varlistentry>
742
743                         <varlistentry>
744                                 <term><varname>IgnoreOnSnapshot=</varname></term>
745
746                                 <listitem><para>Takes a boolean
747                                 argument. If <option>true</option>,
748                                 this unit will not be included in
749                                 snapshots. Defaults to
750                                 <option>true</option> for device and
751                                 snapshot units, <option>false</option>
752                                 for the others.</para></listitem>
753                         </varlistentry>
754
755                         <varlistentry>
756                                 <term><varname>StopWhenUnneeded=</varname></term>
757
758                                 <listitem><para>Takes a boolean
759                                 argument. If <option>true</option>,
760                                 this unit will be stopped when it is
761                                 no longer used. Note that in order to
762                                 minimize the work to be executed,
763                                 systemd will not stop units by default
764                                 unless they are conflicting with other
765                                 units, or the user explicitly
766                                 requested their shut down. If this
767                                 option is set, a unit will be
768                                 automatically cleaned up if no other
769                                 active unit requires it. Defaults to
770                                 <option>false</option>.</para></listitem>
771                         </varlistentry>
772
773                         <varlistentry>
774                                 <term><varname>RefuseManualStart=</varname></term>
775                                 <term><varname>RefuseManualStop=</varname></term>
776
777                                 <listitem><para>Takes a boolean
778                                 argument. If <option>true</option>,
779                                 this unit can only be activated
780                                 or deactivated indirectly. In
781                                 this case, explicit start-up
782                                 or termination requested by the
783                                 user is denied, however if it is
784                                 started or stopped as a
785                                 dependency of another unit, start-up
786                                 or termination will succeed. This
787                                 is mostly a safety feature to ensure
788                                 that the user does not accidentally
789                                 activate units that are not intended
790                                 to be activated explicitly, and not
791                                 accidentally deactivate units that are
792                                 not intended to be deactivated.
793                                 These options default to
794                                 <option>false</option>.</para></listitem>
795                         </varlistentry>
796
797                         <varlistentry>
798                                 <term><varname>AllowIsolate=</varname></term>
799
800                                 <listitem><para>Takes a boolean
801                                 argument. If <option>true</option>,
802                                 this unit may be used with the
803                                 <command>systemctl isolate</command>
804                                 command. Otherwise, this will be
805                                 refused. It probably is a good idea to
806                                 leave this disabled except for target
807                                 units that shall be used similar to
808                                 runlevels in SysV init systems, just
809                                 as a precaution to avoid unusable
810                                 system states. This option defaults to
811                                 <option>false</option>.</para></listitem>
812                         </varlistentry>
813
814                         <varlistentry>
815                                 <term><varname>DefaultDependencies=</varname></term>
816
817                                 <listitem><para>Takes a boolean
818                                 argument. If <option>true</option>,
819                                 (the default), a few default
820                                 dependencies will implicitly be
821                                 created for the unit. The actual
822                                 dependencies created depend on the
823                                 unit type. For example, for service
824                                 units, these dependencies ensure that
825                                 the service is started only after
826                                 basic system initialization is
827                                 completed and is properly terminated on
828                                 system shutdown. See the respective
829                                 man pages for details. Generally, only
830                                 services involved with early boot or
831                                 late shutdown should set this option
832                                 to <option>false</option>. It is
833                                 highly recommended to leave this
834                                 option enabled for the majority of
835                                 common units. If set to
836                                 <option>false</option>, this option
837                                 does not disable all implicit
838                                 dependencies, just non-essential
839                                 ones.</para></listitem>
840                         </varlistentry>
841
842                         <varlistentry>
843                                 <term><varname>JobTimeoutSec=</varname></term>
844
845                                 <listitem><para>When clients are
846                                 waiting for a job of this unit to
847                                 complete, time out after the specified
848                                 time. If this time limit is reached,
849                                 the job will be cancelled, the unit
850                                 however will not change state or even
851                                 enter the <literal>failed</literal>
852                                 mode. This value defaults to 0 (job
853                                 timeouts disabled), except for device
854                                 units. NB: this timeout is independent
855                                 from any unit-specific timeout (for
856                                 example, the timeout set with
857                                 <varname>Timeout=</varname> in service
858                                 units) as the job timeout has no
859                                 effect on the unit itself, only on the
860                                 job that might be pending for it. Or
861                                 in other words: unit-specific timeouts
862                                 are useful to abort unit state
863                                 changes, and revert them. The job
864                                 timeout set with this option however
865                                 is useful to abort only the job
866                                 waiting for the unit state to
867                                 change.</para></listitem>
868                         </varlistentry>
869
870                         <varlistentry>
871                                 <term><varname>ConditionPathExists=</varname></term>
872                                 <term><varname>ConditionPathExistsGlob=</varname></term>
873                                 <term><varname>ConditionPathIsDirectory=</varname></term>
874                                 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
875                                 <term><varname>ConditionPathIsMountPoint=</varname></term>
876                                 <term><varname>ConditionPathIsReadWrite=</varname></term>
877                                 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
878                                 <term><varname>ConditionFileNotEmpty=</varname></term>
879                                 <term><varname>ConditionFileIsExecutable=</varname></term>
880                                 <term><varname>ConditionKernelCommandLine=</varname></term>
881                                 <term><varname>ConditionVirtualization=</varname></term>
882                                 <term><varname>ConditionSecurity=</varname></term>
883                                 <term><varname>ConditionCapability=</varname></term>
884                                 <term><varname>ConditionHost=</varname></term>
885                                 <term><varname>ConditionACPower=</varname></term>
886                                 <term><varname>ConditionNull=</varname></term>
887
888                                 <listitem><para>Before starting a unit
889                                 verify that the specified condition is
890                                 true. If it is not true, the starting
891                                 of the unit will be skipped, however
892                                 all ordering dependencies of it are
893                                 still respected. A failing condition
894                                 will not result in the unit being
895                                 moved into a failure state. The
896                                 condition is checked at the time the
897                                 queued start job is to be
898                                 executed.</para>
899
900                                 <para>With
901                                 <varname>ConditionPathExists=</varname>
902                                 a file existence condition is
903                                 checked before a unit is started. If
904                                 the specified absolute path name does
905                                 not exist, the condition will
906                                 fail. If the absolute path name passed
907                                 to
908                                 <varname>ConditionPathExists=</varname>
909                                 is prefixed with an exclamation mark
910                                 (<literal>!</literal>), the test is negated, and the unit
911                                 is only started if the path does not
912                                 exist.</para>
913
914                                 <para><varname>ConditionPathExistsGlob=</varname>
915                                 is similar to
916                                 <varname>ConditionPathExists=</varname>,
917                                 but checks for the existence of at
918                                 least one file or directory matching
919                                 the specified globbing pattern.</para>
920
921                                 <para><varname>ConditionPathIsDirectory=</varname>
922                                 is similar to
923                                 <varname>ConditionPathExists=</varname>
924                                 but verifies whether a certain path
925                                 exists and is a
926                                 directory.</para>
927
928                                 <para><varname>ConditionPathIsSymbolicLink=</varname>
929                                 is similar to
930                                 <varname>ConditionPathExists=</varname>
931                                 but verifies whether a certain path
932                                 exists and is a symbolic
933                                 link.</para>
934
935                                 <para><varname>ConditionPathIsMountPoint=</varname>
936                                 is similar to
937                                 <varname>ConditionPathExists=</varname>
938                                 but verifies whether a certain path
939                                 exists and is a mount
940                                 point.</para>
941
942                                 <para><varname>ConditionPathIsReadWrite=</varname>
943                                 is similar to
944                                 <varname>ConditionPathExists=</varname>
945                                 but verifies whether the underlying
946                                 file system is readable and writable
947                                 (i.e. not mounted
948                                 read-only).</para>
949
950                                 <para><varname>ConditionDirectoryNotEmpty=</varname>
951                                 is similar to
952                                 <varname>ConditionPathExists=</varname>
953                                 but verifies whether a certain path
954                                 exists and is a non-empty
955                                 directory.</para>
956
957                                 <para><varname>ConditionFileNotEmpty=</varname>
958                                 is similar to
959                                 <varname>ConditionPathExists=</varname>
960                                 but verifies whether a certain path
961                                 exists and refers to a regular file
962                                 with a non-zero size.</para>
963
964                                 <para><varname>ConditionFileIsExecutable=</varname>
965                                 is similar to
966                                 <varname>ConditionPathExists=</varname>
967                                 but verifies whether a certain path
968                                 exists, is a regular file and marked
969                                 executable.</para>
970
971                                 <para>Similar,
972                                 <varname>ConditionKernelCommandLine=</varname>
973                                 may be used to check whether a
974                                 specific kernel command line option is
975                                 set (or if prefixed with the
976                                 exclamation mark unset). The argument
977                                 must either be a single word, or an
978                                 assignment (i.e. two words, separated
979                                 <literal>=</literal>). In the former
980                                 case the kernel command line is
981                                 searched for the word appearing as is,
982                                 or as left hand side of an
983                                 assignment. In the latter case the
984                                 exact assignment is looked for with
985                                 right and left hand side
986                                 matching.</para>
987
988                                 <para><varname>ConditionVirtualization=</varname>
989                                 may be used to check whether the
990                                 system is executed in a virtualized
991                                 environment and optionally test
992                                 whether it is a specific
993                                 implementation. Takes either boolean
994                                 value to check if being executed in
995                                 any virtualized environment, or one of
996                                 <varname>vm</varname> and
997                                 <varname>container</varname> to test
998                                 against a generic type of
999                                 virtualization solution, or one of
1000                                 <varname>qemu</varname>,
1001                                 <varname>kvm</varname>,
1002                                 <varname>vmware</varname>,
1003                                 <varname>microsoft</varname>,
1004                                 <varname>oracle</varname>,
1005                                 <varname>xen</varname>,
1006                                 <varname>bochs</varname>,
1007                                 <varname>chroot</varname>,
1008                                 <varname>uml</varname>,
1009                                 <varname>openvz</varname>,
1010                                 <varname>lxc</varname>,
1011                                 <varname>lxc-libvirt</varname>,
1012                                 <varname>systemd-nspawn</varname> to
1013                                 test against a specific
1014                                 implementation. If multiple
1015                                 virtualization technologies are nested,
1016                                 only the innermost is considered. The
1017                                 test may be negated by prepending an
1018                                 exclamation mark.</para>
1019
1020                                 <para><varname>ConditionSecurity=</varname>
1021                                 may be used to check whether the given
1022                                 security module is enabled on the
1023                                 system. Currently the recognized values
1024                                 values are <varname>selinux</varname>,
1025                                 <varname>apparmor</varname>,
1026                                 <varname>ima</varname> and
1027                                 <varname>smack</varname>.
1028                                 The test may be negated by prepending
1029                                 an exclamation
1030                                 mark.</para>
1031
1032                                 <para><varname>ConditionCapability=</varname>
1033                                 may be used to check whether the given
1034                                 capability exists in the capability
1035                                 bounding set of the service manager
1036                                 (i.e. this does not check whether
1037                                 capability is actually available in
1038                                 the permitted or effective sets, see
1039                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1040                                 for details). Pass a capability name
1041                                 such as <literal>CAP_MKNOD</literal>,
1042                                 possibly prefixed with an exclamation
1043                                 mark to negate the check.</para>
1044
1045                                 <para><varname>ConditionHost=</varname>
1046                                 may be used to match against the
1047                                 hostname or machine ID of the
1048                                 host. This either takes a hostname
1049                                 string (optionally with shell style
1050                                 globs) which is tested against the
1051                                 locally set hostname as returned by
1052                                 <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
1053                                 or a machine ID formatted as string
1054                                 (see
1055                                 <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
1056                                 The test may be negated by prepending
1057                                 an exclamation mark.</para>
1058
1059                                 <para><varname>ConditionACPower=</varname>
1060                                 may be used to check whether the
1061                                 system has AC power, or is exclusively
1062                                 battery powered at the time of
1063                                 activation of the unit. This takes a
1064                                 boolean argument. If set to
1065                                 <varname>true</varname>, the condition
1066                                 will hold only if at least one AC
1067                                 connector of the system is connected
1068                                 to a power source, or if no AC
1069                                 connectors are known. Conversely, if
1070                                 set to <varname>false</varname>, the
1071                                 condition will hold only if there is
1072                                 at least one AC connector known and
1073                                 all AC connectors are disconnected
1074                                 from a power source.</para>
1075
1076                                 <para>Finally,
1077                                 <varname>ConditionNull=</varname> may
1078                                 be used to add a constant condition
1079                                 check value to the unit. It takes a
1080                                 boolean argument. If set to
1081                                 <varname>false</varname>, the condition
1082                                 will always fail, otherwise
1083                                 succeed.</para>
1084
1085                                 <para>If multiple conditions are
1086                                 specified, the unit will be executed if
1087                                 all of them apply (i.e. a logical AND
1088                                 is applied). Condition checks can be
1089                                 prefixed with a pipe symbol (|) in
1090                                 which case a condition becomes a
1091                                 triggering condition. If at least one
1092                                 triggering condition is defined for a
1093                                 unit, then the unit will be executed if
1094                                 at least one of the triggering
1095                                 conditions apply and all of the
1096                                 non-triggering conditions. If you
1097                                 prefix an argument with the pipe
1098                                 symbol and an exclamation mark, the
1099                                 pipe symbol must be passed first, the
1100                                 exclamation second. Except for
1101                                 <varname>ConditionPathIsSymbolicLink=</varname>,
1102                                 all path checks follow symlinks. If
1103                                 any of these options is assigned the
1104                                 empty string, the list of conditions is
1105                                 reset completely, all previous
1106                                 condition settings (of any kind) will
1107                                 have no effect.</para></listitem>
1108                         </varlistentry>
1109
1110                         <varlistentry>
1111                                 <term><varname>SourcePath=</varname></term>
1112                                 <listitem><para>A path to a
1113                                 configuration file this unit has been
1114                                 generated from. This is primarily
1115                                 useful for implementation of generator
1116                                 tools that convert configuration from
1117                                 an external configuration file format
1118                                 into native unit files. Thus
1119                                 functionality should not be used in
1120                                 normal units.</para></listitem>
1121                         </varlistentry>
1122                 </variablelist>
1123
1124                 <para>Unit file may include a [Install] section, which
1125                 carries installation information for the unit. This
1126                 section is not interpreted by
1127                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1128                 during runtime. It is used exclusively by the
1129                 <command>enable</command> and
1130                 <command>disable</command> commands of the
1131                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1132                 tool during installation of a unit:</para>
1133
1134                 <variablelist class='unit-directives'>
1135                         <varlistentry>
1136                                 <term><varname>Alias=</varname></term>
1137
1138                                 <listitem><para>A space-seperated list
1139                                 of additional names this unit shall be
1140                                 installed under. The names listed here
1141                                 must have the same suffix (i.e. type)
1142                                 as the unit file name. This option may
1143                                 be specified more than once, in which
1144                                 case all listed names are used. At
1145                                 installation time, <command>systemctl
1146                                 enable</command> will create symlinks
1147                                 from these names to the unit
1148                                 filename.</para></listitem>
1149                         </varlistentry>
1150
1151                         <varlistentry>
1152                                 <term><varname>WantedBy=</varname></term>
1153                                 <term><varname>RequiredBy=</varname></term>
1154
1155                                 <listitem><para>This option may be
1156                                 used more than once, or a
1157                                 space-separated list of unit names may
1158                                 be given. A symbolic link is created
1159                                 in the <filename>.wants/</filename> or
1160                                 <filename>.requires/</filename>
1161                                 directory of each of the listed units
1162                                 when this unit is installed by
1163                                 <command>systemctl enable</command>.
1164                                 This has the effect that a dependency
1165                                 of type <varname>Wants=</varname> or
1166                                 <varname>Requires=</varname> is added
1167                                 from the listed unit to the current
1168                                 unit. The primary result is that the
1169                                 current unit will be started when the
1170                                 listed unit is started. See the
1171                                 description of
1172                                 <varname>Wants=</varname> and
1173                                 <varname>Requires=</varname> in the
1174                                 [Unit] section for details.</para>
1175
1176                                 <para><command>WantedBy=foo.service</command>
1177                                 in a service
1178                                 <filename>bar.service</filename> is
1179                                 mostly equivalent to
1180                                 <command>Alias=foo.service.wants/bar.service</command>
1181                                 in the same file. In case of template
1182                                 units, <command>systemctl enable</command>
1183                                 must be called with an instance name, and
1184                                 this instance will be added to the
1185                                 <filename>.wants/</filename> or
1186                                 <filename>.requires/</filename> list
1187                                 of the listed unit.
1188                                 E.g. <command>WantedBy=getty.target</command>
1189                                 in a service
1190                                 <filename>getty@.service</filename>
1191                                 will result in <command>systemctl
1192                                 enable getty@tty2.service</command>
1193                                 creating a
1194                                 <filename>getty.target.wants/getty@tty2.service</filename>
1195                                 link to <filename>getty@.service</filename>.
1196                                 </para></listitem>
1197                         </varlistentry>
1198
1199                         <varlistentry>
1200                                 <term><varname>Also=</varname></term>
1201
1202                                 <listitem><para>Additional units to
1203                                 install/deinstall when this unit is
1204                                 installed/deinstalled. If the user
1205                                 requests installation/deinstallation
1206                                 of a unit with this option configured,
1207                                 <command>systemctl enable</command>
1208                                 and <command>systemctl
1209                                 disable</command> will automatically
1210                                 install/uninstall units listed in this option as
1211                                 well.</para>
1212
1213                                 <para>This option may be used more
1214                                 than once, or a space-separated list
1215                                 of unit names may be
1216                                 given.</para></listitem>
1217                         </varlistentry>
1218                 </variablelist>
1219
1220                 <para>The following specifiers are interpreted in the
1221                 Install section: %n, %N, %p, %i, %U, %u, %m, %H, %b, %v.
1222                 For their meaning see the next section.
1223                 </para>
1224         </refsect1>
1225
1226         <refsect1>
1227                 <title>Specifiers</title>
1228
1229                 <para>Many settings resolve specifiers which may be
1230                 used to write generic unit files referring to runtime
1231                 or unit parameters that are replaced when the unit
1232                 files are loaded. The following specifiers are
1233                 understood:</para>
1234
1235                 <table>
1236                   <title>Specifiers available in unit files</title>
1237                   <tgroup cols='3' align='left' colsep='1' rowsep='1'>
1238                     <colspec colname="spec" />
1239                     <colspec colname="mean" />
1240                     <colspec colname="detail" />
1241                     <thead>
1242                       <row>
1243                         <entry>Specifier</entry>
1244                         <entry>Meaning</entry>
1245                         <entry>Details</entry>
1246                       </row>
1247                     </thead>
1248                     <tbody>
1249                       <row>
1250                         <entry><literal>%n</literal></entry>
1251                         <entry>Full unit name</entry>
1252                         <entry></entry>
1253                       </row>
1254                       <row>
1255                         <entry><literal>%N</literal></entry>
1256                         <entry>Unescaped full unit name</entry>
1257                         <entry></entry>
1258                       </row>
1259                       <row>
1260                         <entry><literal>%p</literal></entry>
1261                         <entry>Prefix name</entry>
1262                         <entry>For instantiated units this refers to the string before the @. For non-instantiated units this refers to to the name of the unit with the type suffix removed.</entry>
1263                       </row>
1264                       <row>
1265                         <entry><literal>%P</literal></entry>
1266                         <entry>Unescaped prefix name</entry>
1267                         <entry></entry>
1268                       </row>
1269                       <row>
1270                         <entry><literal>%i</literal></entry>
1271                         <entry>Instance name</entry>
1272                         <entry>For instantiated units: this is the string between the <literal>@</literal> character and the suffix.</entry>
1273                       </row>
1274                       <row>
1275                         <entry><literal>%I</literal></entry>
1276                         <entry>Unescaped instance name</entry>
1277                         <entry></entry>
1278                       </row>
1279                       <row>
1280                         <entry><literal>%f</literal></entry>
1281                         <entry>Unescaped filename</entry>
1282                         <entry>This is either the unescaped instance name (if applicable) with <filename>/</filename> prepended (if applicable), or the prefix name similarly prepended with <filename>/</filename>.</entry>
1283                       </row>
1284                       <row>
1285                         <entry><literal>%c</literal></entry>
1286                         <entry>Control group path of the unit</entry>
1287                         <entry></entry>
1288                       </row>
1289                       <row>
1290                         <entry><literal>%r</literal></entry>
1291                         <entry>Root control group path where units are placed.</entry>
1292                         <entry>For system instances, this usually resolves to <filename>/system</filename>, except in containers, where the path might be prefixed with the container's root control group.</entry>
1293                       </row>
1294                       <row>
1295                         <entry><literal>%R</literal></entry>
1296                         <entry>Parent directory of the control group path where units are placed.</entry>
1297                         <entry>For system instances, this usually
1298                         resolves to <filename>/</filename>, except in
1299                         containers, where this resolves to the
1300                         container's root directory.</entry>
1301                       </row>
1302                       <row>
1303                         <entry><literal>%t</literal></entry>
1304                         <entry>Runtime socket dir</entry>
1305                         <entry>This is either <filename>/run</filename> (for the system manager) or <literal>$XDG_RUNTIME_DIR</literal> (for user managers).</entry>
1306                       </row>
1307                       <row>
1308                         <entry><literal>%u</literal></entry>
1309                         <entry>User name</entry>
1310                         <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1311                       </row>
1312                       <row>
1313                         <entry><literal>%U</literal></entry>
1314                         <entry>User UID</entry>
1315                         <entry>This is the UID of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1316                       </row>
1317                       <row>
1318                         <entry><literal>%h</literal></entry>
1319                         <entry>User home directory</entry>
1320                         <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>
1321                       </row>
1322                       <row>
1323                         <entry><literal>%s</literal></entry>
1324                         <entry>User shell</entry>
1325                         <entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd instance.  If the user is <literal>root</literal> (UID equal to 0), the shell configured in account database is ignored and <filename>/bin/sh</filename> is always used.</entry>
1326                       </row>
1327                       <row>
1328                         <entry><literal>%m</literal></entry>
1329                         <entry>Machine ID</entry>
1330                         <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>
1331                       </row>
1332                       <row>
1333                         <entry><literal>%b</literal></entry>
1334                         <entry>Boot ID</entry>
1335                         <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
1336                       </row>
1337                       <row>
1338                         <entry><literal>%H</literal></entry>
1339                         <entry>Host name</entry>
1340                         <entry>The hostname of the running system.</entry>
1341                       </row>
1342                       <row>
1343                         <entry><literal>%v</literal></entry>
1344                         <entry>Kernel release</entry>
1345                         <entry>Identical to <command>uname -r</command> output.</entry>
1346                       </row>
1347                       <row>
1348                         <entry><literal>%%</literal></entry>
1349                         <entry>Escaped %</entry>
1350                         <entry>Single percent sign.</entry>
1351                       </row>
1352                     </tbody>
1353                   </tgroup>
1354                 </table>
1355         </refsect1>
1356
1357         <refsect1>
1358                 <title>See Also</title>
1359                 <para>
1360                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1361                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1362                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1363                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1364                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1365                         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1366                         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1367                         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1368                         <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1369                         <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1370                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1371                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1372                         <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1373                         <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1374                         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1375                         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1376                         <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1377                         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1378                         <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1379                 </para>
1380         </refsect1>
1381
1382 </refentry>