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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
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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.
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21   Lesser General Public License for more details.
22
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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>$XDG_CONFIG_HOME/systemd/user/*</filename>
74 <filename>$HOME/.config/systemd/user/*</filename>
75 <filename>/etc/systemd/user/*</filename>
76 <filename>/run/systemd/user/*</filename>
77 <filename>/usr/lib/systemd/user/*</filename>
78 <filename>...</filename>
79                 </literallayout></para>
80         </refsynopsisdiv>
81
82         <refsect1>
83                 <title>Description</title>
84
85                 <para>A unit configuration file encodes information
86                 about a service, a socket, a device, a mount point, an
87                 automount point, a swap file or partition, a start-up
88                 target, a watched file system path, a timer controlled
89                 and supervised by
90                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
91                 a temporary system state snapshot, a resource
92                 management slice or a group of externally created
93                 processes. The syntax is inspired by <ulink
94                 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
95                 Desktop Entry Specification</ulink>
96                 <filename>.desktop</filename> files, which are in turn
97                 inspired by Microsoft Windows
98                 <filename>.ini</filename> files.</para>
99
100                 <para>This man page lists the common configuration
101                 options of all the unit types. These options need to
102                 be configured in the [Unit] or [Install]
103                 sections of the unit files.</para>
104
105                 <para>In addition to the generic [Unit] and [Install]
106                 sections described here, each unit may have a
107                 type-specific section, e.g. [Service] for a service
108                 unit. See the respective man pages for more
109                 information:
110                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
111                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
112                 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
113                 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
114                 <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
115                 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
116                 <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
117                 <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
118                 <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
119                 <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
120                 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
121                 <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
122                 </para>
123
124                 <para>Various settings are allowed to be specified
125                 more than once, in which case the interpretation
126                 depends on the setting. Often, multiple settings form
127                 a list, and setting to an empty value "resets", which
128                 means that previous assignments are ignored. When this
129                 is allowed, it is mentioned in the description of the
130                 setting. Note that using multiple assignments to the
131                 same value makes the unit file incompatible with
132                 parsers for the XDG <filename>.desktop</filename> file
133                 format.</para>
134
135                 <para>Unit files are loaded from a set of paths
136                 determined during compilation, described in the next section.
137                 </para>
138
139                 <para>Unit files may contain additional options on top
140                 of those listed here. If systemd encounters an unknown
141                 option, it will write a warning log message but
142                 continue loading the unit. If an option is prefixed
143                 with <option>X-</option>, it is ignored completely by
144                 systemd. Applications may use this to include
145                 additional information in the unit files.</para>
146
147                 <para>Boolean arguments used in unit files can be
148                 written in various formats. For positive settings the
149                 strings <option>1</option>, <option>yes</option>,
150                 <option>true</option> and <option>on</option> are
151                 equivalent. For negative settings, the strings
152                 <option>0</option>, <option>no</option>,
153                 <option>false</option> and <option>off</option> are
154                 equivalent.</para>
155
156                 <para>Time span values encoded in unit files can be
157                 written in various formats. A stand-alone number
158                 specifies a time in seconds. If suffixed with a time
159                 unit, the unit is honored. A concatenation of multiple
160                 values with units is supported, in which case the
161                 values are added up. Example: "50" refers to 50
162                 seconds; "2min 200ms" refers to 2 minutes plus 200
163                 milliseconds, i.e. 120200ms. The following time units
164                 are understood: s, min, h, d, w, ms, us. For details
165                 see
166                 <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
167
168                 <para>Empty lines and lines starting with # or ; are
169                 ignored. This may be used for commenting. Lines ending
170                 in a backslash are concatenated with the following
171                 line while reading and the backslash is replaced by a
172                 space character. This may be used to wrap long lines.</para>
173
174                 <para>Along with a unit file
175                 <filename>foo.service</filename>, the directory
176                 <filename>foo.service.wants/</filename> may exist. All
177                 unit files symlinked from such a directory are
178                 implicitly added as dependencies of type
179                 <varname>Wanted=</varname> to the unit. This is useful
180                 to hook units into the start-up of other units,
181                 without having to modify their unit files. For details
182                 about the semantics of <varname>Wanted=</varname>, see
183                 below. The preferred way to create symlinks in the
184                 <filename>.wants/</filename> directory of a unit file
185                 is with the <command>enable</command> command of the
186                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
187                 tool which reads information from the [Install]
188                 section of unit files (see below). A similar
189                 functionality exists for <varname>Requires=</varname>
190                 type dependencies as well, the directory suffix is
191                 <filename>.requires/</filename> in this case.</para>
192
193                 <para>Along with a unit file
194                 <filename>foo.service</filename>, a directory
195                 <filename>foo.service.d/</filename> may exist. All
196                 files with the suffix <literal>.conf</literal> from
197                 this directory will be parsed after the file itself is
198                 parsed. This is useful to alter or add configuration
199                 settings to a unit, without having to modify their
200                 unit files. Make sure that the file that is included
201                 has the appropriate section headers before any
202                 directive.</para>
203
204                 <para>Note that while systemd offers a flexible
205                 dependency system between units it is recommended to
206                 use this functionality only sparingly and instead rely
207                 on techniques such as bus-based or socket-based
208                 activation which make dependencies implicit, resulting
209                 in a both simpler and more flexible system.</para>
210
211                 <para>Some unit names reflect paths existing in the
212                 file system namespace. Example: a device unit
213                 <filename>dev-sda.device</filename> refers to a device
214                 with the device node <filename noindex='true'>/dev/sda</filename> in
215                 the file system namespace. If this applies, a special
216                 way to escape the path name is used, so that the
217                 result is usable as part of a filename. Basically,
218                 given a path, "/" is replaced by "-", and all
219                 unprintable characters and the "-" are replaced by
220                 C-style "\x20" escapes. The root directory "/" is
221                 encoded as single dash, while otherwise the initial
222                 and ending "/" is removed from all paths during
223                 transformation. This escaping is reversible.</para>
224
225                 <para>Optionally, units may be instantiated from a
226                 template file at runtime. This allows creation of
227                 multiple units from a single configuration file. If
228                 systemd looks for a unit configuration file, it will
229                 first search for the literal unit name in the
230                 file system. If that yields no success and the unit
231                 name contains an <literal>@</literal> character, systemd will look for a
232                 unit template that shares the same name but with the
233                 instance string (i.e. the part between the <literal>@</literal> character
234                 and the suffix) removed. Example: if a service
235                 <filename>getty@tty3.service</filename> is requested
236                 and no file by that name is found, systemd will look
237                 for <filename>getty@.service</filename> and
238                 instantiate a service from that configuration file if
239                 it is found.</para>
240
241                 <para>To refer to the instance string from
242                 within the configuration file you may use the special
243                 <literal>%i</literal> specifier in many of the
244                 configuration options. See below for details.</para>
245
246                 <para>If a unit file is empty (i.e. has the file size
247                 0) or is symlinked to <filename>/dev/null</filename>,
248                 its configuration will not be loaded and it appears
249                 with a load state of <literal>masked</literal>, and
250                 cannot be activated. Use this as an effective way to
251                 fully disable a unit, making it impossible to start it
252                 even manually.</para>
253
254                 <para>The unit file format is covered by the
255                 <ulink
256                 url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
257                 Stability Promise</ulink>.</para>
258
259         </refsect1>
260
261         <refsect1>
262                 <title>Unit Load Path</title>
263
264                 <para>Unit files are loaded from a set of paths
265                 determined during compilation, described in the two
266                 tables below. Unit files found in directories listed
267                 earlier override files with the same name in
268                 directories lower in the list.</para>
269
270                 <para>When systemd is running in user mode
271                 (<option>--user</option>) and the variable
272                 <varname>$SYSTEMD_UNIT_PATH</varname> is set, this
273                 contents of this variable overrides the unit load
274                 path.
275                 </para>
276
277                 <table>
278                   <title>
279                     Load path when running in system mode (<option>--system</option>).
280                   </title>
281
282                   <tgroup cols='2'>
283                     <colspec colname='path' />
284                     <colspec colname='expl' />
285                     <thead>
286                       <row>
287                         <entry>Path</entry>
288                         <entry>Description</entry>
289                       </row>
290                     </thead>
291                     <tbody>
292                       <row>
293                         <entry><filename>/etc/systemd/system</filename></entry>
294                         <entry>Local configuration</entry>
295                       </row>
296                       <row>
297                         <entry><filename>/run/systemd/system</filename></entry>
298                         <entry>Runtime units</entry>
299                       </row>
300                       <row>
301                         <entry><filename>/usr/lib/systemd/system</filename></entry>
302                         <entry>Units of installed packages</entry>
303                       </row>
304                     </tbody>
305                   </tgroup>
306                 </table>
307
308                 <table>
309                   <title>
310                     Load path when running in user mode (<option>--user</option>).
311                   </title>
312
313                   <tgroup cols='2'>
314                     <colspec colname='path' />
315                     <colspec colname='expl' />
316                     <thead>
317                       <row>
318                         <entry>Path</entry>
319                         <entry>Description</entry>
320                       </row>
321                     </thead>
322                     <tbody>
323                       <row>
324                         <entry><filename>$XDG_CONFIG_HOME/systemd/user</filename></entry>
325                         <entry>User configuration (only used when $XDG_CONFIG_HOME is set)</entry>
326                       </row>
327                       <row>
328                         <entry><filename>$HOME/.config/systemd/user</filename></entry>
329                         <entry>User configuration (only used when $XDG_CONFIG_HOME is not set)</entry>
330                       </row>
331                       <row>
332                         <entry><filename>/etc/systemd/user</filename></entry>
333                         <entry>Local configuration</entry>
334                       </row>
335                       <row>
336                         <entry><filename>/run/systemd/user</filename></entry>
337                         <entry>Runtime units</entry>
338                       </row>
339                       <row>
340                         <entry><filename>/usr/lib/systemd/user</filename></entry>
341                         <entry>Units of installed packages</entry>
342                       </row>
343                     </tbody>
344                   </tgroup>
345                 </table>
346
347                 <para>Additional units might be loaded into systemd
348                 ("linked") from directories not on the unit load
349                 path. See the <command>link</command> command for
350                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. Also,
351                 some units are dynamically created via generators
352                 <ulink
353                 url="http://www.freedesktop.org/wiki/Software/systemd/Generators/">Generators</ulink>.
354                 </para>
355         </refsect1>
356
357         <refsect1>
358                 <title>[Unit] Section Options</title>
359
360                 <para>Unit file may include a [Unit] section, which
361                 carries generic information about the unit that is not
362                 dependent on the type of unit:</para>
363
364                 <variablelist class='unit-directives'>
365
366                         <varlistentry>
367                                 <term><varname>Description=</varname></term>
368                                 <listitem><para>A free-form string
369                                 describing the unit. This is intended
370                                 for use in UIs to show descriptive
371                                 information along with the unit
372                                 name. The description should contain a name
373                                 that means something to the end user.
374                                 <literal>Apache2 Web Server</literal> is a good
375                                 example. Bad examples are
376                                 <literal>high-performance light-weight HTTP
377                                 server</literal> (too generic) or
378                                 <literal>Apache2</literal> (too specific and
379                                 meaningless for people who do not know
380                                 Apache).</para></listitem>
381                         </varlistentry>
382
383                         <varlistentry>
384                                 <term><varname>Documentation=</varname></term>
385                                 <listitem><para>A space-separated list
386                                 of URIs referencing documentation for
387                                 this unit or its
388                                 configuration. Accepted are only URIs
389                                 of the types
390                                 <literal>http://</literal>,
391                                 <literal>https://</literal>,
392                                 <literal>file:</literal>,
393                                 <literal>info:</literal>,
394                                 <literal>man:</literal>. For more
395                                 information about the syntax of these
396                                 URIs, see
397                                 <citerefentry><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
398                                 URIs should be listed in order of
399                                 relevance, starting with the most
400                                 relevant. It is a good idea to first
401                                 reference documentation that explains
402                                 what the unit's purpose is, followed
403                                 by how it is configured, followed by
404                                 any other related documentation. This
405                                 option may be specified more than once,
406                                 in which case the specified list of
407                                 URIs is merged. If the empty string is
408                                 assigned to this option, the list is
409                                 reset and all prior assignments will
410                                 have no effect.</para></listitem>
411                         </varlistentry>
412
413                         <varlistentry>
414                                 <term><varname>Requires=</varname></term>
415
416                                 <listitem><para>Configures requirement
417                                 dependencies on other units. If this
418                                 unit gets activated, the units listed
419                                 here will be activated as well. If one
420                                 of the other units gets deactivated or
421                                 its activation fails, this unit will
422                                 be deactivated. This option may be
423                                 specified more than once or multiple
424                                 space-separated units may be specified
425                                 in one option in which case
426                                 requirement dependencies for all
427                                 listed names will be created. Note
428                                 that requirement dependencies do not
429                                 influence the order in which services
430                                 are started or stopped. This has to be
431                                 configured independently with the
432                                 <varname>After=</varname> or
433                                 <varname>Before=</varname> options. If
434                                 a unit
435                                 <filename>foo.service</filename>
436                                 requires a unit
437                                 <filename>bar.service</filename> as
438                                 configured with
439                                 <varname>Requires=</varname> and no
440                                 ordering is configured with
441                                 <varname>After=</varname> or
442                                 <varname>Before=</varname>, then both
443                                 units will be started simultaneously
444                                 and without any delay between them if
445                                 <filename>foo.service</filename> is
446                                 activated. Often it is a better choice
447                                 to use <varname>Wants=</varname>
448                                 instead of
449                                 <varname>Requires=</varname> in order
450                                 to achieve a system that is more
451                                 robust when dealing with failing
452                                 services.</para>
453
454                                 <para>Note that dependencies of this
455                                 type may also be configured outside of
456                                 the unit configuration file by
457                                 adding a symlink to a
458                                 <filename>.requires/</filename> directory
459                                 accompanying the unit file. For
460                                 details see above.</para></listitem>
461                         </varlistentry>
462
463                         <varlistentry>
464                                 <term><varname>RequiresOverridable=</varname></term>
465
466                                 <listitem><para>Similar to
467                                 <varname>Requires=</varname>.
468                                 Dependencies listed in
469                                 <varname>RequiresOverridable=</varname>
470                                 which cannot be fulfilled or fail to
471                                 start are ignored if the startup was
472                                 explicitly requested by the user. If
473                                 the start-up was pulled in indirectly
474                                 by some dependency or automatic
475                                 start-up of units that is not
476                                 requested by the user, this dependency
477                                 must be fulfilled and otherwise the
478                                 transaction fails. Hence, this option
479                                 may be used to configure dependencies
480                                 that are normally honored unless the
481                                 user explicitly starts up the unit, in
482                                 which case whether they failed or not
483                                 is irrelevant.</para></listitem>
484
485                         </varlistentry>
486                         <varlistentry>
487                                 <term><varname>Requisite=</varname></term>
488                                 <term><varname>RequisiteOverridable=</varname></term>
489
490                                 <listitem><para>Similar to
491                                 <varname>Requires=</varname> and
492                                 <varname>RequiresOverridable=</varname>,
493                                 respectively. However, if the units
494                                 listed here are not started already,
495                                 they will not be started and the
496                                 transaction will fail immediately.
497                                 </para></listitem>
498                         </varlistentry>
499
500                         <varlistentry>
501                                 <term><varname>Wants=</varname></term>
502
503                                 <listitem><para>A weaker version of
504                                 <varname>Requires=</varname>. Units
505                                 listed in this option will be started
506                                 if the configuring unit is. However,
507                                 if the listed units fail to start
508                                 or cannot be added to the transaction,
509                                 this has no impact on the validity of
510                                 the transaction as a whole. This is
511                                 the recommended way to hook start-up
512                                 of one unit to the start-up of another
513                                 unit.</para>
514
515                                 <para>Note that dependencies of this
516                                 type may also be configured outside of
517                                 the unit configuration file by adding
518                                 symlinks to a
519                                 <filename>.wants/</filename> directory
520                                 accompanying the unit file. For
521                                 details, see above.</para></listitem>
522                         </varlistentry>
523
524                         <varlistentry>
525                                 <term><varname>BindsTo=</varname></term>
526
527                                 <listitem><para>Configures requirement
528                                 dependencies, very similar in style to
529                                 <varname>Requires=</varname>, however
530                                 in addition to this behavior, it also
531                                 declares that this unit is stopped
532                                 when any of the units listed suddenly
533                                 disappears. Units can suddenly,
534                                 unexpectedly disappear if a service
535                                 terminates on its own choice, a device
536                                 is unplugged or a mount point
537                                 unmounted without involvement of
538                                 systemd.</para></listitem>
539                         </varlistentry>
540
541                         <varlistentry>
542                                 <term><varname>PartOf=</varname></term>
543
544                                 <listitem><para>Configures dependencies
545                                 similar to <varname>Requires=</varname>,
546                                 but limited to stopping and restarting
547                                 of units. When systemd stops or restarts
548                                 the units listed here, the action is
549                                 propagated to this unit.
550                                 Note that this is a one-way dependency —
551                                 changes to this unit do not affect the
552                                 listed units.
553                                 </para></listitem>
554                         </varlistentry>
555
556                         <varlistentry>
557                                 <term><varname>Conflicts=</varname></term>
558
559                                 <listitem><para>A space-separated list
560                                 of unit names. Configures negative
561                                 requirement dependencies. If a unit
562                                 has a <varname>Conflicts=</varname>
563                                 setting on another unit, starting the
564                                 former will stop the latter and vice
565                                 versa. Note that this setting is
566                                 independent of and orthogonal to the
567                                 <varname>After=</varname> and
568                                 <varname>Before=</varname> ordering
569                                 dependencies.</para>
570
571                                 <para>If a unit A that conflicts with
572                                 a unit B is scheduled to be started at
573                                 the same time as B, the transaction
574                                 will either fail (in case both are
575                                 required part of the transaction) or
576                                 be modified to be fixed (in case one
577                                 or both jobs are not a required part
578                                 of the transaction). In the latter
579                                 case, the job that is not the required
580                                 will be removed, or in case both are
581                                 not required, the unit that conflicts
582                                 will be started and the unit that is
583                                 conflicted is
584                                 stopped.</para></listitem>
585                         </varlistentry>
586
587                         <varlistentry>
588                                 <term><varname>Before=</varname></term>
589                                 <term><varname>After=</varname></term>
590
591                                 <listitem><para>A space-separated list
592                                 of unit names. Configures ordering
593                                 dependencies between units. If a unit
594                                 <filename>foo.service</filename>
595                                 contains a setting
596                                 <option>Before=bar.service</option>
597                                 and both units are being started,
598                                 <filename>bar.service</filename>'s
599                                 start-up is delayed until
600                                 <filename>foo.service</filename> is
601                                 started up. Note that this setting is
602                                 independent of and orthogonal to the
603                                 requirement dependencies as configured
604                                 by <varname>Requires=</varname>. It is
605                                 a common pattern to include a unit
606                                 name in both the
607                                 <varname>After=</varname> and
608                                 <varname>Requires=</varname> option, in
609                                 which case the unit listed will be
610                                 started before the unit that is
611                                 configured with these options. This
612                                 option may be specified more than
613                                 once, in which case ordering
614                                 dependencies for all listed names are
615                                 created. <varname>After=</varname> is
616                                 the inverse of
617                                 <varname>Before=</varname>, i.e. while
618                                 <varname>After=</varname> ensures that
619                                 the configured unit is started after
620                                 the listed unit finished starting up,
621                                 <varname>Before=</varname> ensures the
622                                 opposite, i.e.  that the configured
623                                 unit is fully started up before the
624                                 listed unit is started. Note that when
625                                 two units with an ordering dependency
626                                 between them are shut down, the
627                                 inverse of the start-up order is
628                                 applied. i.e. if a unit is configured
629                                 with <varname>After=</varname> on
630                                 another unit, the former is stopped
631                                 before the latter if both are shut
632                                 down. If one unit with an ordering
633                                 dependency on another unit is shut
634                                 down while the latter is started up,
635                                 the shut down is ordered before the
636                                 start-up regardless of whether the
637                                 ordering dependency is actually of
638                                 type <varname>After=</varname> or
639                                 <varname>Before=</varname>. If two
640                                 units have no ordering dependencies
641                                 between them, they are shut down or
642                                 started up simultaneously, and no
643                                 ordering takes
644                                 place. </para></listitem>
645                         </varlistentry>
646
647                         <varlistentry>
648                                 <term><varname>OnFailure=</varname></term>
649
650                                 <listitem><para>A space-separated list
651                                 of one or more units that are
652                                 activated when this unit enters the
653                                 <literal>failed</literal>
654                                 state.</para></listitem>
655                         </varlistentry>
656
657                         <varlistentry>
658                                 <term><varname>PropagatesReloadTo=</varname></term>
659                                 <term><varname>ReloadPropagatedFrom=</varname></term>
660
661                                 <listitem><para>A space-separated list
662                                 of one or more units where reload
663                                 requests on this unit will be
664                                 propagated to, or reload requests on
665                                 the other unit will be propagated to
666                                 this unit, respectively. Issuing a
667                                 reload request on a unit will
668                                 automatically also enqueue a reload
669                                 request on all units that the reload
670                                 request shall be propagated to via
671                                 these two settings.</para></listitem>
672                         </varlistentry>
673
674                         <varlistentry>
675                                 <term><varname>JoinsNamespaceOf=</varname></term>
676
677                                 <listitem><para>For units that start
678                                 processes (such as service units),
679                                 lists one or more other units whose
680                                 network and/or temporary file
681                                 namespace to join. This only applies
682                                 to unit types which support the
683                                 <varname>PrivateNetwork=</varname> and
684                                 <varname>PrivateTmp=</varname>
685                                 directives (see
686                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
687                                 for details). If a unit that has this
688                                 setting set is started, its processes
689                                 will see the same
690                                 <filename>/tmp</filename>,
691                                 <filename>/tmp/var</filename> and
692                                 network namespace as one listed unit
693                                 that is started. If multiple listed
694                                 units are already started, it is not
695                                 defined which namespace is
696                                 joined. Note that this setting only
697                                 has an effect if
698                                 <varname>PrivateNetwork=</varname>
699                                 and/or <varname>PrivateTmp=</varname>
700                                 is enabled for both the unit that
701                                 joins the namespace and the unit whose
702                                 namespace is joined.</para></listitem>
703                         </varlistentry>
704
705                         <varlistentry>
706                                 <term><varname>RequiresMountsFor=</varname></term>
707
708                                 <listitem><para>Takes a space-separated
709                                 list of absolute paths. Automatically
710                                 adds dependencies of type
711                                 <varname>Requires=</varname> and
712                                 <varname>After=</varname> for all
713                                 mount units required to access the
714                                 specified path.</para></listitem>
715                         </varlistentry>
716
717                         <varlistentry>
718                                 <term><varname>OnFailureJobMode=</varname></term>
719
720                                 <listitem><para>Takes a value of
721                                 <literal>fail</literal>,
722                                 <literal>replace</literal>,
723                                 <literal>replace-irreversibly</literal>,
724                                 <literal>isolate</literal>,
725                                 <literal>flush</literal>,
726                                 <literal>ignore-dependencies</literal>
727                                 or
728                                 <literal>ignore-requirements</literal>. Defaults
729                                 to
730                                 <literal>replace</literal>. Specifies
731                                 how the units listed in
732                                 <varname>OnFailure=</varname> will be
733                                 enqueued. See
734                                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
735                                 <option>--job-mode=</option> option
736                                 for details on the possible values. If
737                                 this is set to
738                                 <literal>isolate</literal>, only a
739                                 single unit may be listed in
740                                 <varname>OnFailure=</varname>..</para></listitem>
741                         </varlistentry>
742
743                         <varlistentry>
744                                 <term><varname>IgnoreOnIsolate=</varname></term>
745
746                                 <listitem><para>Takes a boolean
747                                 argument. If <option>true</option>,
748                                 this unit will not be stopped when
749                                 isolating another unit. Defaults to
750                                 <option>false</option>.</para></listitem>
751                         </varlistentry>
752
753                         <varlistentry>
754                                 <term><varname>IgnoreOnSnapshot=</varname></term>
755
756                                 <listitem><para>Takes a boolean
757                                 argument. If <option>true</option>,
758                                 this unit will not be included in
759                                 snapshots. Defaults to
760                                 <option>true</option> for device and
761                                 snapshot units, <option>false</option>
762                                 for the others.</para></listitem>
763                         </varlistentry>
764
765                         <varlistentry>
766                                 <term><varname>StopWhenUnneeded=</varname></term>
767
768                                 <listitem><para>Takes a boolean
769                                 argument. If <option>true</option>,
770                                 this unit will be stopped when it is
771                                 no longer used. Note that in order to
772                                 minimize the work to be executed,
773                                 systemd will not stop units by default
774                                 unless they are conflicting with other
775                                 units, or the user explicitly
776                                 requested their shut down. If this
777                                 option is set, a unit will be
778                                 automatically cleaned up if no other
779                                 active unit requires it. Defaults to
780                                 <option>false</option>.</para></listitem>
781                         </varlistentry>
782
783                         <varlistentry>
784                                 <term><varname>RefuseManualStart=</varname></term>
785                                 <term><varname>RefuseManualStop=</varname></term>
786
787                                 <listitem><para>Takes a boolean
788                                 argument. If <option>true</option>,
789                                 this unit can only be activated
790                                 or deactivated indirectly. In
791                                 this case, explicit start-up
792                                 or termination requested by the
793                                 user is denied, however if it is
794                                 started or stopped as a
795                                 dependency of another unit, start-up
796                                 or termination will succeed. This
797                                 is mostly a safety feature to ensure
798                                 that the user does not accidentally
799                                 activate units that are not intended
800                                 to be activated explicitly, and not
801                                 accidentally deactivate units that are
802                                 not intended to be deactivated.
803                                 These options default to
804                                 <option>false</option>.</para></listitem>
805                         </varlistentry>
806
807                         <varlistentry>
808                                 <term><varname>AllowIsolate=</varname></term>
809
810                                 <listitem><para>Takes a boolean
811                                 argument. If <option>true</option>,
812                                 this unit may be used with the
813                                 <command>systemctl isolate</command>
814                                 command. Otherwise, this will be
815                                 refused. It probably is a good idea to
816                                 leave this disabled except for target
817                                 units that shall be used similar to
818                                 runlevels in SysV init systems, just
819                                 as a precaution to avoid unusable
820                                 system states. This option defaults to
821                                 <option>false</option>.</para></listitem>
822                         </varlistentry>
823
824                         <varlistentry>
825                                 <term><varname>DefaultDependencies=</varname></term>
826
827                                 <listitem><para>Takes a boolean
828                                 argument. If <option>true</option>,
829                                 (the default), a few default
830                                 dependencies will implicitly be
831                                 created for the unit. The actual
832                                 dependencies created depend on the
833                                 unit type. For example, for service
834                                 units, these dependencies ensure that
835                                 the service is started only after
836                                 basic system initialization is
837                                 completed and is properly terminated on
838                                 system shutdown. See the respective
839                                 man pages for details. Generally, only
840                                 services involved with early boot or
841                                 late shutdown should set this option
842                                 to <option>false</option>. It is
843                                 highly recommended to leave this
844                                 option enabled for the majority of
845                                 common units. If set to
846                                 <option>false</option>, this option
847                                 does not disable all implicit
848                                 dependencies, just non-essential
849                                 ones.</para></listitem>
850                         </varlistentry>
851
852                         <varlistentry>
853                                 <term><varname>JobTimeoutSec=</varname></term>
854
855                                 <listitem><para>When clients are
856                                 waiting for a job of this unit to
857                                 complete, time out after the specified
858                                 time. If this time limit is reached,
859                                 the job will be cancelled, the unit
860                                 however will not change state or even
861                                 enter the <literal>failed</literal>
862                                 mode. This value defaults to 0 (job
863                                 timeouts disabled), except for device
864                                 units. NB: this timeout is independent
865                                 from any unit-specific timeout (for
866                                 example, the timeout set with
867                                 <varname>Timeout=</varname> in service
868                                 units) as the job timeout has no
869                                 effect on the unit itself, only on the
870                                 job that might be pending for it. Or
871                                 in other words: unit-specific timeouts
872                                 are useful to abort unit state
873                                 changes, and revert them. The job
874                                 timeout set with this option however
875                                 is useful to abort only the job
876                                 waiting for the unit state to
877                                 change.</para></listitem>
878                         </varlistentry>
879
880                         <varlistentry>
881                                 <term><varname>ConditionArchitecture=</varname></term>
882                                 <term><varname>ConditionVirtualization=</varname></term>
883                                 <term><varname>ConditionHost=</varname></term>
884                                 <term><varname>ConditionKernelCommandLine=</varname></term>
885                                 <term><varname>ConditionSecurity=</varname></term>
886                                 <term><varname>ConditionCapability=</varname></term>
887                                 <term><varname>ConditionACPower=</varname></term>
888                                 <term><varname>ConditionPathExists=</varname></term>
889                                 <term><varname>ConditionPathExistsGlob=</varname></term>
890                                 <term><varname>ConditionPathIsDirectory=</varname></term>
891                                 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
892                                 <term><varname>ConditionPathIsMountPoint=</varname></term>
893                                 <term><varname>ConditionPathIsReadWrite=</varname></term>
894                                 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
895                                 <term><varname>ConditionFileNotEmpty=</varname></term>
896                                 <term><varname>ConditionFileIsExecutable=</varname></term>
897                                 <term><varname>ConditionNull=</varname></term>
898
899                                 <listitem><para>Before starting a unit
900                                 verify that the specified condition is
901                                 true. If it is not true, the starting
902                                 of the unit will be skipped, however
903                                 all ordering dependencies of it are
904                                 still respected. A failing condition
905                                 will not result in the unit being
906                                 moved into a failure state. The
907                                 condition is checked at the time the
908                                 queued start job is to be
909                                 executed.</para>
910
911                                 <para><varname>ConditionArchitecture=</varname>
912                                 may be used to check whether the
913                                 system is running on a specific
914                                 architecture. Takes one of
915                                 <varname>x86</varname>,
916                                 <varname>x86-64</varname>,
917                                 <varname>ppc</varname>,
918                                 <varname>ppc64</varname>,
919                                 <varname>ia64</varname>,
920                                 <varname>parisc</varname>,
921                                 <varname>parisc64</varname>,
922                                 <varname>s390</varname>,
923                                 <varname>s390x</varname>,
924                                 <varname>sparc</varname>,
925                                 <varname>sparc64</varname>,
926                                 <varname>mips</varname>,
927                                 <varname>mips64</varname>,
928                                 <varname>alpha</varname>,
929                                 <varname>arm</varname>,
930                                 <varname>arm-be</varname>,
931                                 <varname>arm64</varname>,
932                                 <varname>arm64-be</varname>,
933                                 <varname>sh</varname>,
934                                 <varname>sh64</varname>,
935                                 <varname>m86k</varname> to test
936                                 against a specific architecture. The
937                                 architecture is determined from the
938                                 information returned by
939                                 <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
940                                 and is thus subject to
941                                 <citerefentry><refentrytitle>personality</refentrytitle><manvolnum>2</manvolnum></citerefentry>. Note
942                                 that a <varname>Personality=</varname>
943                                 setting in the same unit file has no
944                                 effect on this condition. A special
945                                 architecture name
946                                 <varname>native</varname> is mapped to
947                                 the architecture the system manager
948                                 itself is compiled for. The test may
949                                 be negated by prepending an
950                                 exclamation mark.</para>
951
952                                 <para><varname>ConditionVirtualization=</varname>
953                                 may be used to check whether the
954                                 system is executed in a virtualized
955                                 environment and optionally test
956                                 whether it is a specific
957                                 implementation. Takes either boolean
958                                 value to check if being executed in
959                                 any virtualized environment, or one of
960                                 <varname>vm</varname> and
961                                 <varname>container</varname> to test
962                                 against a generic type of
963                                 virtualization solution, or one of
964                                 <varname>qemu</varname>,
965                                 <varname>kvm</varname>,
966                                 <varname>vmware</varname>,
967                                 <varname>microsoft</varname>,
968                                 <varname>oracle</varname>,
969                                 <varname>xen</varname>,
970                                 <varname>bochs</varname>,
971                                 <varname>chroot</varname>,
972                                 <varname>uml</varname>,
973                                 <varname>openvz</varname>,
974                                 <varname>lxc</varname>,
975                                 <varname>lxc-libvirt</varname>,
976                                 <varname>systemd-nspawn</varname> to
977                                 test against a specific
978                                 implementation. If multiple
979                                 virtualization technologies are nested,
980                                 only the innermost is considered. The
981                                 test may be negated by prepending an
982                                 exclamation mark.</para>
983
984                                 <para><varname>ConditionHost=</varname>
985                                 may be used to match against the
986                                 hostname or machine ID of the
987                                 host. This either takes a hostname
988                                 string (optionally with shell style
989                                 globs) which is tested against the
990                                 locally set hostname as returned by
991                                 <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
992                                 or a machine ID formatted as string
993                                 (see
994                                 <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
995                                 The test may be negated by prepending
996                                 an exclamation mark.</para>
997
998                                 <para><varname>ConditionKernelCommandLine=</varname>
999                                 may be used to check whether a
1000                                 specific kernel command line option is
1001                                 set (or if prefixed with the
1002                                 exclamation mark unset). The argument
1003                                 must either be a single word, or an
1004                                 assignment (i.e. two words, separated
1005                                 <literal>=</literal>). In the former
1006                                 case the kernel command line is
1007                                 searched for the word appearing as is,
1008                                 or as left hand side of an
1009                                 assignment. In the latter case the
1010                                 exact assignment is looked for with
1011                                 right and left hand side
1012                                 matching.</para>
1013
1014                                 <para><varname>ConditionSecurity=</varname>
1015                                 may be used to check whether the given
1016                                 security module is enabled on the
1017                                 system. Currently the recognized values
1018                                 values are <varname>selinux</varname>,
1019                                 <varname>apparmor</varname>,
1020                                 <varname>ima</varname> and
1021                                 <varname>smack</varname>.
1022                                 The test may be negated by prepending
1023                                 an exclamation
1024                                 mark.</para>
1025
1026                                 <para><varname>ConditionCapability=</varname>
1027                                 may be used to check whether the given
1028                                 capability exists in the capability
1029                                 bounding set of the service manager
1030                                 (i.e. this does not check whether
1031                                 capability is actually available in
1032                                 the permitted or effective sets, see
1033                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1034                                 for details). Pass a capability name
1035                                 such as <literal>CAP_MKNOD</literal>,
1036                                 possibly prefixed with an exclamation
1037                                 mark to negate the check.</para>
1038
1039                                 <para><varname>ConditionACPower=</varname>
1040                                 may be used to check whether the
1041                                 system has AC power, or is exclusively
1042                                 battery powered at the time of
1043                                 activation of the unit. This takes a
1044                                 boolean argument. If set to
1045                                 <varname>true</varname>, the condition
1046                                 will hold only if at least one AC
1047                                 connector of the system is connected
1048                                 to a power source, or if no AC
1049                                 connectors are known. Conversely, if
1050                                 set to <varname>false</varname>, the
1051                                 condition will hold only if there is
1052                                 at least one AC connector known and
1053                                 all AC connectors are disconnected
1054                                 from a power source.</para>
1055
1056                                 <para>With
1057                                 <varname>ConditionPathExists=</varname>
1058                                 a file existence condition is
1059                                 checked before a unit is started. If
1060                                 the specified absolute path name does
1061                                 not exist, the condition will
1062                                 fail. If the absolute path name passed
1063                                 to
1064                                 <varname>ConditionPathExists=</varname>
1065                                 is prefixed with an exclamation mark
1066                                 (<literal>!</literal>), the test is negated, and the unit
1067                                 is only started if the path does not
1068                                 exist.</para>
1069
1070                                 <para><varname>ConditionPathExistsGlob=</varname>
1071                                 is similar to
1072                                 <varname>ConditionPathExists=</varname>,
1073                                 but checks for the existence of at
1074                                 least one file or directory matching
1075                                 the specified globbing pattern.</para>
1076
1077                                 <para><varname>ConditionPathIsDirectory=</varname>
1078                                 is similar to
1079                                 <varname>ConditionPathExists=</varname>
1080                                 but verifies whether a certain path
1081                                 exists and is a
1082                                 directory.</para>
1083
1084                                 <para><varname>ConditionPathIsSymbolicLink=</varname>
1085                                 is similar to
1086                                 <varname>ConditionPathExists=</varname>
1087                                 but verifies whether a certain path
1088                                 exists and is a symbolic
1089                                 link.</para>
1090
1091                                 <para><varname>ConditionPathIsMountPoint=</varname>
1092                                 is similar to
1093                                 <varname>ConditionPathExists=</varname>
1094                                 but verifies whether a certain path
1095                                 exists and is a mount
1096                                 point.</para>
1097
1098                                 <para><varname>ConditionPathIsReadWrite=</varname>
1099                                 is similar to
1100                                 <varname>ConditionPathExists=</varname>
1101                                 but verifies whether the underlying
1102                                 file system is readable and writable
1103                                 (i.e. not mounted
1104                                 read-only).</para>
1105
1106                                 <para><varname>ConditionDirectoryNotEmpty=</varname>
1107                                 is similar to
1108                                 <varname>ConditionPathExists=</varname>
1109                                 but verifies whether a certain path
1110                                 exists and is a non-empty
1111                                 directory.</para>
1112
1113                                 <para><varname>ConditionFileNotEmpty=</varname>
1114                                 is similar to
1115                                 <varname>ConditionPathExists=</varname>
1116                                 but verifies whether a certain path
1117                                 exists and refers to a regular file
1118                                 with a non-zero size.</para>
1119
1120                                 <para><varname>ConditionFileIsExecutable=</varname>
1121                                 is similar to
1122                                 <varname>ConditionPathExists=</varname>
1123                                 but verifies whether a certain path
1124                                 exists, is a regular file and marked
1125                                 executable.</para>
1126
1127                                 <para>Finally,
1128                                 <varname>ConditionNull=</varname> may
1129                                 be used to add a constant condition
1130                                 check value to the unit. It takes a
1131                                 boolean argument. If set to
1132                                 <varname>false</varname>, the condition
1133                                 will always fail, otherwise
1134                                 succeed.</para>
1135
1136                                 <para>If multiple conditions are
1137                                 specified, the unit will be executed if
1138                                 all of them apply (i.e. a logical AND
1139                                 is applied). Condition checks can be
1140                                 prefixed with a pipe symbol (|) in
1141                                 which case a condition becomes a
1142                                 triggering condition. If at least one
1143                                 triggering condition is defined for a
1144                                 unit, then the unit will be executed if
1145                                 at least one of the triggering
1146                                 conditions apply and all of the
1147                                 non-triggering conditions. If you
1148                                 prefix an argument with the pipe
1149                                 symbol and an exclamation mark, the
1150                                 pipe symbol must be passed first, the
1151                                 exclamation second. Except for
1152                                 <varname>ConditionPathIsSymbolicLink=</varname>,
1153                                 all path checks follow symlinks. If
1154                                 any of these options is assigned the
1155                                 empty string, the list of conditions is
1156                                 reset completely, all previous
1157                                 condition settings (of any kind) will
1158                                 have no effect.</para></listitem>
1159                         </varlistentry>
1160
1161                         <varlistentry>
1162                                 <term><varname>SourcePath=</varname></term>
1163                                 <listitem><para>A path to a
1164                                 configuration file this unit has been
1165                                 generated from. This is primarily
1166                                 useful for implementation of generator
1167                                 tools that convert configuration from
1168                                 an external configuration file format
1169                                 into native unit files. Thus
1170                                 functionality should not be used in
1171                                 normal units.</para></listitem>
1172                         </varlistentry>
1173                 </variablelist>
1174
1175         </refsect1>
1176
1177         <refsect1>
1178                 <title>[Install] Section Options</title>
1179
1180                 <para>Unit file may include a [Install] section, which
1181                 carries installation information for the unit. This
1182                 section is not interpreted by
1183                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1184                 during runtime. It is used exclusively by the
1185                 <command>enable</command> and
1186                 <command>disable</command> commands of the
1187                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1188                 tool during installation of a unit:</para>
1189
1190                 <variablelist class='unit-directives'>
1191                         <varlistentry>
1192                                 <term><varname>Alias=</varname></term>
1193
1194                                 <listitem><para>A space-seperated list
1195                                 of additional names this unit shall be
1196                                 installed under. The names listed here
1197                                 must have the same suffix (i.e. type)
1198                                 as the unit file name. This option may
1199                                 be specified more than once, in which
1200                                 case all listed names are used. At
1201                                 installation time, <command>systemctl
1202                                 enable</command> will create symlinks
1203                                 from these names to the unit
1204                                 filename.</para></listitem>
1205                         </varlistentry>
1206
1207                         <varlistentry>
1208                                 <term><varname>WantedBy=</varname></term>
1209                                 <term><varname>RequiredBy=</varname></term>
1210
1211                                 <listitem><para>This option may be
1212                                 used more than once, or a
1213                                 space-separated list of unit names may
1214                                 be given. A symbolic link is created
1215                                 in the <filename>.wants/</filename> or
1216                                 <filename>.requires/</filename>
1217                                 directory of each of the listed units
1218                                 when this unit is installed by
1219                                 <command>systemctl enable</command>.
1220                                 This has the effect that a dependency
1221                                 of type <varname>Wants=</varname> or
1222                                 <varname>Requires=</varname> is added
1223                                 from the listed unit to the current
1224                                 unit. The primary result is that the
1225                                 current unit will be started when the
1226                                 listed unit is started. See the
1227                                 description of
1228                                 <varname>Wants=</varname> and
1229                                 <varname>Requires=</varname> in the
1230                                 [Unit] section for details.</para>
1231
1232                                 <para><command>WantedBy=foo.service</command>
1233                                 in a service
1234                                 <filename>bar.service</filename> is
1235                                 mostly equivalent to
1236                                 <command>Alias=foo.service.wants/bar.service</command>
1237                                 in the same file. In case of template
1238                                 units, <command>systemctl enable</command>
1239                                 must be called with an instance name, and
1240                                 this instance will be added to the
1241                                 <filename>.wants/</filename> or
1242                                 <filename>.requires/</filename> list
1243                                 of the listed unit.
1244                                 E.g. <command>WantedBy=getty.target</command>
1245                                 in a service
1246                                 <filename>getty@.service</filename>
1247                                 will result in <command>systemctl
1248                                 enable getty@tty2.service</command>
1249                                 creating a
1250                                 <filename>getty.target.wants/getty@tty2.service</filename>
1251                                 link to <filename>getty@.service</filename>.
1252                                 </para></listitem>
1253                         </varlistentry>
1254
1255                         <varlistentry>
1256                                 <term><varname>Also=</varname></term>
1257
1258                                 <listitem><para>Additional units to
1259                                 install/deinstall when this unit is
1260                                 installed/deinstalled. If the user
1261                                 requests installation/deinstallation
1262                                 of a unit with this option configured,
1263                                 <command>systemctl enable</command>
1264                                 and <command>systemctl
1265                                 disable</command> will automatically
1266                                 install/uninstall units listed in this option as
1267                                 well.</para>
1268
1269                                 <para>This option may be used more
1270                                 than once, or a space-separated list
1271                                 of unit names may be
1272                                 given.</para></listitem>
1273                         </varlistentry>
1274                 </variablelist>
1275
1276                 <para>The following specifiers are interpreted in the
1277                 Install section: %n, %N, %p, %i, %U, %u, %m, %H, %b, %v.
1278                 For their meaning see the next section.
1279                 </para>
1280         </refsect1>
1281
1282         <refsect1>
1283                 <title>Specifiers</title>
1284
1285                 <para>Many settings resolve specifiers which may be
1286                 used to write generic unit files referring to runtime
1287                 or unit parameters that are replaced when the unit
1288                 files are loaded. The following specifiers are
1289                 understood:</para>
1290
1291                 <table>
1292                   <title>Specifiers available in unit files</title>
1293                   <tgroup cols='3' align='left' colsep='1' rowsep='1'>
1294                     <colspec colname="spec" />
1295                     <colspec colname="mean" />
1296                     <colspec colname="detail" />
1297                     <thead>
1298                       <row>
1299                         <entry>Specifier</entry>
1300                         <entry>Meaning</entry>
1301                         <entry>Details</entry>
1302                       </row>
1303                     </thead>
1304                     <tbody>
1305                       <row>
1306                         <entry><literal>%n</literal></entry>
1307                         <entry>Full unit name</entry>
1308                         <entry></entry>
1309                       </row>
1310                       <row>
1311                         <entry><literal>%N</literal></entry>
1312                         <entry>Unescaped full unit name</entry>
1313                         <entry>Same as <literal>%n</literal>, but with escaping undone</entry>
1314                       </row>
1315                       <row>
1316                         <entry><literal>%p</literal></entry>
1317                         <entry>Prefix name</entry>
1318                         <entry>For instantiated units, this refers to the string before the <literal>@</literal> character of the unit name. For non-instantiated units, this refers to the name of the unit with the type suffix removed.</entry>
1319                       </row>
1320                       <row>
1321                         <entry><literal>%P</literal></entry>
1322                         <entry>Unescaped prefix name</entry>
1323                         <entry>Same as <literal>%p</literal>, but with escaping undone</entry>
1324                       </row>
1325                       <row>
1326                         <entry><literal>%i</literal></entry>
1327                         <entry>Instance name</entry>
1328                         <entry>For instantiated units: this is the string between the <literal>@</literal> character and the suffix of the unit name.</entry>
1329                       </row>
1330                       <row>
1331                         <entry><literal>%I</literal></entry>
1332                         <entry>Unescaped instance name</entry>
1333                         <entry>Same as <literal>%i</literal>, but with escaping undone</entry>
1334                       </row>
1335                       <row>
1336                         <entry><literal>%f</literal></entry>
1337                         <entry>Unescaped filename</entry>
1338                         <entry>This is either the unescaped instance name (if applicable) with <filename>/</filename> prepended (if applicable), or the prefix name prepended with <filename>/</filename>.</entry>
1339                       </row>
1340                       <row>
1341                         <entry><literal>%c</literal></entry>
1342                         <entry>Control group path of the unit</entry>
1343                         <entry>This path does not include the <filename>/sys/fs/cgroup/systemd/</filename> prefix.</entry>
1344                       </row>
1345                       <row>
1346                         <entry><literal>%r</literal></entry>
1347                         <entry>Control group path of the slice the unit is placed in</entry>
1348                         <entry>This usually maps to the parent cgroup path of <literal>%c</literal>.</entry>
1349                       </row>
1350                       <row>
1351                         <entry><literal>%R</literal></entry>
1352                         <entry>Root control group path below which slices and units are placed</entry>
1353                         <entry>For system instances, this resolves to <filename>/</filename>, except in containers, where this maps to the container's root control group path.</entry>
1354                       </row>
1355                       <row>
1356                         <entry><literal>%t</literal></entry>
1357                         <entry>Runtime directory</entry>
1358                         <entry>This is either <filename>/run</filename> (for the system manager) or the path <literal>$XDG_RUNTIME_DIR</literal> resolves to (for user managers).</entry>
1359                       </row>
1360                       <row>
1361                         <entry><literal>%u</literal></entry>
1362                         <entry>User name</entry>
1363                         <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1364                       </row>
1365                       <row>
1366                         <entry><literal>%U</literal></entry>
1367                         <entry>User UID</entry>
1368                         <entry>This is the numeric UID of the configured user of the unit, or (if none is set) the user running the systemd user instance. Note that this specifier is not available for units run by the systemd system instance (as opposed to those run by a systemd user instance), unless the user has been configured as a numeric UID in the first place or the configured user is the root user.</entry>
1369                       </row>
1370                       <row>
1371                         <entry><literal>%h</literal></entry>
1372                         <entry>User home directory</entry>
1373                         <entry>This is the home directory of the configured user of the unit, or (if none is set) the user running the systemd user instance. Similar to <literal>%U</literal>, this specifier is not available for units run by the systemd system instance, unless the configured user is the root user.</entry>
1374                       </row>
1375                       <row>
1376                         <entry><literal>%s</literal></entry>
1377                         <entry>User shell</entry>
1378                         <entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd user instance. Similar to <literal>%U</literal>, this specifier is not available for units run by the systemd system instance, unless the configured user is the root user.</entry>
1379                       </row>
1380                       <row>
1381                         <entry><literal>%m</literal></entry>
1382                         <entry>Machine ID</entry>
1383                         <entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
1384                       </row>
1385                       <row>
1386                         <entry><literal>%b</literal></entry>
1387                         <entry>Boot ID</entry>
1388                         <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
1389                       </row>
1390                       <row>
1391                         <entry><literal>%H</literal></entry>
1392                         <entry>Host name</entry>
1393                         <entry>The hostname of the running system at the point in time the unit configuation is loaded.</entry>
1394                       </row>
1395                       <row>
1396                         <entry><literal>%v</literal></entry>
1397                         <entry>Kernel release</entry>
1398                         <entry>Identical to <command>uname -r</command> output</entry>
1399                       </row>
1400                       <row>
1401                         <entry><literal>%%</literal></entry>
1402                         <entry>Single percent sign</entry>
1403                         <entry>Use <literal>%%</literal> in place of <literal>%</literal> to specify a single percent sign.</entry>
1404                       </row>
1405                     </tbody>
1406                   </tgroup>
1407                 </table>
1408         </refsect1>
1409
1410         <refsect1>
1411                 <title>See Also</title>
1412                 <para>
1413                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1414                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1415                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1416                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1417                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1418                         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1419                         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1420                         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1421                         <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1422                         <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1423                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1424                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1425                         <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1426                         <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1427                         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1428                         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1429                         <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1430                         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1431                         <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1432                 </para>
1433         </refsect1>
1434
1435 </refentry>