chiark / gitweb /
man: minor typo fix
[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
13   systemd is free software; you can redistribute it and/or modify it
14   under the terms of the GNU Lesser General Public License as published by
15   the Free Software Foundation; either version 2.1 of the License, or
16   (at your option) any later version.
17
18   systemd is distributed in the hope that it will be useful, but
19   WITHOUT ANY WARRANTY; without even the implied warranty of
20   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21   Lesser General Public License for more details.
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>$XDG_CONFIG_HOME/systemd/user/*</filename>
74 <filename>$HOME/.config/systemd/user/*</filename>
75 <filename>/etc/systemd/user/*</filename>
76 <filename>$XDG_RUNTIME_DIR/systemd/user/*</filename>
77 <filename>/run/systemd/user/*</filename>
78 <filename>$XDG_DATA_HOME/systemd/user/*</filename>
79 <filename>$HOME/.local/share/systemd/user/*</filename>
80 <filename>/usr/lib/systemd/user/*</filename>
81 <filename>...</filename>
82                 </literallayout></para>
83         </refsynopsisdiv>
84
85         <refsect1>
86                 <title>Description</title>
87
88                 <para>A unit configuration file encodes information
89                 about a service, a socket, a device, a mount point, an
90                 automount point, a swap file or partition, a start-up
91                 target, a watched file system path, a timer controlled
92                 and supervised by
93                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
94                 a temporary system state snapshot, a resource
95                 management slice or a group of externally created
96                 processes. The syntax is inspired by <ulink
97                 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
98                 Desktop Entry Specification</ulink>
99                 <filename>.desktop</filename> files, which are in turn
100                 inspired by Microsoft Windows
101                 <filename>.ini</filename> files.</para>
102
103                 <para>This man page lists the common configuration
104                 options of all the unit types. These options need to
105                 be configured in the [Unit] or [Install]
106                 sections of the unit files.</para>
107
108                 <para>In addition to the generic [Unit] and [Install]
109                 sections described here, each unit may have a
110                 type-specific section, e.g. [Service] for a service
111                 unit. See the respective man pages for more
112                 information:
113                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
114                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
115                 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
116                 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
117                 <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
118                 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
119                 <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
120                 <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
121                 <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
122                 <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
123                 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
124                 <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
125                 </para>
126
127                 <para>Various settings are allowed to be specified
128                 more than once, in which case the interpretation
129                 depends on the setting. Often, multiple settings form
130                 a list, and setting to an empty value "resets", which
131                 means that previous assignments are ignored. When this
132                 is allowed, it is mentioned in the description of the
133                 setting. Note that using multiple assignments to the
134                 same value makes the unit file incompatible with
135                 parsers for the XDG <filename>.desktop</filename> file
136                 format.</para>
137
138                 <para>Unit files are loaded from a set of paths
139                 determined during compilation, described in the next section.
140                 </para>
141
142                 <para>Unit files may contain additional options on top
143                 of those listed here. If systemd encounters an unknown
144                 option, it will write a warning log message but
145                 continue loading the unit. If an option or section name
146                 is prefixed with <option>X-</option>, it is ignored
147                 completely by systemd. Options within an ignored
148                 section do not need the prefix. Applications may use
149                 this to include additional information in the unit
150                 files.</para>
151
152                 <para>Boolean arguments used in unit files can be
153                 written in various formats. For positive settings the
154                 strings <option>1</option>, <option>yes</option>,
155                 <option>true</option> and <option>on</option> are
156                 equivalent. For negative settings, the strings
157                 <option>0</option>, <option>no</option>,
158                 <option>false</option> and <option>off</option> are
159                 equivalent.</para>
160
161                 <para>Time span values encoded in unit files can be
162                 written in various formats. A stand-alone number
163                 specifies a time in seconds. If suffixed with a time
164                 unit, the unit is honored. A concatenation of multiple
165                 values with units is supported, in which case the
166                 values are added up. Example: "50" refers to 50
167                 seconds; "2min 200ms" refers to 2 minutes plus 200
168                 milliseconds, i.e. 120200ms. The following time units
169                 are understood: s, min, h, d, w, ms, us. For details
170                 see
171                 <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
172
173                 <para>Empty lines and lines starting with # or ; are
174                 ignored. This may be used for commenting. Lines ending
175                 in a backslash are concatenated with the following
176                 line while reading and the backslash is replaced by a
177                 space character. This may be used to wrap long lines.</para>
178
179                 <para>Along with a unit file
180                 <filename>foo.service</filename>, the directory
181                 <filename>foo.service.wants/</filename> may exist. All
182                 unit files symlinked from such a directory are
183                 implicitly added as dependencies of type
184                 <varname>Wants=</varname> to the unit. This is useful
185                 to hook units into the start-up of other units,
186                 without having to modify their unit files. For details
187                 about the semantics of <varname>Wants=</varname>, see
188                 below. The preferred way to create symlinks in the
189                 <filename>.wants/</filename> directory of a unit file
190                 is with the <command>enable</command> command of the
191                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
192                 tool which reads information from the [Install]
193                 section of unit files (see below). A similar
194                 functionality exists for <varname>Requires=</varname>
195                 type dependencies as well, the directory suffix is
196                 <filename>.requires/</filename> in this case.</para>
197
198                 <para>Along with a unit file
199                 <filename>foo.service</filename>, a directory
200                 <filename>foo.service.d/</filename> may exist. All
201                 files with the suffix <literal>.conf</literal> from
202                 this directory will be parsed after the file itself is
203                 parsed. This is useful to alter or add configuration
204                 settings to a unit, without having to modify their
205                 unit files. Make sure that the file that is included
206                 has the appropriate section headers before any
207                 directive. Note that for instanced units this logic
208                 will first look for the instance
209                 <literal>.d/</literal> subdirectory and read its
210                 <literal>.conf</literal> files, followed by the
211                 template <literal>.d/</literal> subdirectory and reads
212                 its <literal>.conf</literal> files.</para>
213
214                 <!-- Note that we do not document .include here, as we
215                      consider it mostly obsolete, and want people to
216                      use .d/ drop-ins instead. -->
217
218                 <para>Note that while systemd offers a flexible
219                 dependency system between units it is recommended to
220                 use this functionality only sparingly and instead rely
221                 on techniques such as bus-based or socket-based
222                 activation which make dependencies implicit, resulting
223                 in a both simpler and more flexible system.</para>
224
225                 <para>Some unit names reflect paths existing in the
226                 file system namespace. Example: a device unit
227                 <filename>dev-sda.device</filename> refers to a device
228                 with the device node <filename noindex='true'>/dev/sda</filename> in
229                 the file system namespace. If this applies, a special
230                 way to escape the path name is used, so that the
231                 result is usable as part of a filename. Basically,
232                 given a path, "/" is replaced by "-" and all other
233                 characters which are not ASCII alphanumerics are
234                 replaced by C-style "\x2d" escapes (except that "_"
235                 is never replaced and "." is only replaced when it
236                 would be the first character in the escaped path).
237                 The root directory "/" is encoded as single dash,
238                 while otherwise the initial and ending "/" are removed
239                 from all paths during transformation. This escaping
240                 is reversible. Properly escaped paths can be generated
241                 using the <citerefentry><refentrytitle>systemd-escape</refentrytitle><manvolnum>1</manvolnum></citerefentry>
242                 command.</para>
243
244                 <para>Optionally, units may be instantiated from a
245                 template file at runtime. This allows creation of
246                 multiple units from a single configuration file. If
247                 systemd looks for a unit configuration file, it will
248                 first search for the literal unit name in the
249                 file system. If that yields no success and the unit
250                 name contains an <literal>@</literal> character, systemd will look for a
251                 unit template that shares the same name but with the
252                 instance string (i.e. the part between the <literal>@</literal> character
253                 and the suffix) removed. Example: if a service
254                 <filename>getty@tty3.service</filename> is requested
255                 and no file by that name is found, systemd will look
256                 for <filename>getty@.service</filename> and
257                 instantiate a service from that configuration file if
258                 it is found.</para>
259
260                 <para>To refer to the instance string from
261                 within the configuration file you may use the special
262                 <literal>%i</literal> specifier in many of the
263                 configuration options. See below for details.</para>
264
265                 <para>If a unit file is empty (i.e. has the file size
266                 0) or is symlinked to <filename>/dev/null</filename>,
267                 its configuration will not be loaded and it appears
268                 with a load state of <literal>masked</literal>, and
269                 cannot be activated. Use this as an effective way to
270                 fully disable a unit, making it impossible to start it
271                 even manually.</para>
272
273                 <para>The unit file format is covered by the
274                 <ulink
275                 url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
276                 Stability Promise</ulink>.</para>
277
278         </refsect1>
279
280         <refsect1>
281                 <title>Unit Load Path</title>
282
283                 <para>Unit files are loaded from a set of paths
284                 determined during compilation, described in the two
285                 tables below. Unit files found in directories listed
286                 earlier override files with the same name in
287                 directories lower in the list.</para>
288
289                 <para>When systemd is running in user mode
290                 (<option>--user</option>) and the variable
291                 <varname>$SYSTEMD_UNIT_PATH</varname> is set, the
292                 contents of this variable overrides the unit load
293                 path. If <varname>$SYSTEMD_UNIT_PATH</varname> ends
294                 with an empty component (<literal>:</literal>), the
295                 usual unit load path will be appended to the contents
296                 of the variable.</para>
297
298                 <table>
299                   <title>
300                     Load path when running in system mode (<option>--system</option>).
301                   </title>
302
303                   <tgroup cols='2'>
304                     <colspec colname='path' />
305                     <colspec colname='expl' />
306                     <thead>
307                       <row>
308                         <entry>Path</entry>
309                         <entry>Description</entry>
310                       </row>
311                     </thead>
312                     <tbody>
313                       <row>
314                         <entry><filename>/etc/systemd/system</filename></entry>
315                         <entry>Local configuration</entry>
316                       </row>
317                       <row>
318                         <entry><filename>/run/systemd/system</filename></entry>
319                         <entry>Runtime units</entry>
320                       </row>
321                       <row>
322                         <entry><filename>/usr/lib/systemd/system</filename></entry>
323                         <entry>Units of installed packages</entry>
324                       </row>
325                     </tbody>
326                   </tgroup>
327                 </table>
328
329                 <table>
330                   <title>
331                     Load path when running in user mode (<option>--user</option>).
332                   </title>
333
334                   <tgroup cols='2'>
335                     <colspec colname='path' />
336                     <colspec colname='expl' />
337                     <thead>
338                       <row>
339                         <entry>Path</entry>
340                         <entry>Description</entry>
341                       </row>
342                     </thead>
343                     <tbody>
344                       <row>
345                         <entry><filename>$XDG_CONFIG_HOME/systemd/user</filename></entry>
346                         <entry>User configuration (only used when $XDG_CONFIG_HOME is set)</entry>
347                       </row>
348                       <row>
349                         <entry><filename>$HOME/.config/systemd/user</filename></entry>
350                         <entry>User configuration (only used when $XDG_CONFIG_HOME is not set)</entry>
351                       </row>
352                       <row>
353                         <entry><filename>/etc/systemd/user</filename></entry>
354                         <entry>Local configuration</entry>
355                       </row>
356                       <row>
357                         <entry><filename>$XDG_RUNTIME_DIR/systemd/user</filename></entry>
358                         <entry>Runtime units (only used when $XDG_RUNTIME_DIR is set)</entry>
359                       </row>
360                       <row>
361                         <entry><filename>/run/systemd/user</filename></entry>
362                         <entry>Runtime units</entry>
363                       </row>
364                       <row>
365                         <entry><filename>$XDG_DATA_HOME/systemd/user</filename></entry>
366                         <entry>Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is set)</entry>
367                       </row>
368                       <row>
369                         <entry><filename>$HOME/.local/share/systemd/user</filename></entry>
370                         <entry>Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is not set)</entry>
371                       </row>
372                       <row>
373                         <entry><filename>/usr/lib/systemd/user</filename></entry>
374                         <entry>Units of packages that have been installed system-wide</entry>
375                       </row>
376                     </tbody>
377                   </tgroup>
378                 </table>
379
380                 <para>Additional units might be loaded into systemd
381                 ("linked") from directories not on the unit load
382                 path. See the <command>link</command> command for
383                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. Also,
384                 some units are dynamically created via generators
385                 <ulink
386                 url="http://www.freedesktop.org/wiki/Software/systemd/Generators/">Generators</ulink>.
387                 </para>
388         </refsect1>
389
390         <refsect1>
391                 <title>[Unit] Section Options</title>
392
393                 <para>Unit file may include a [Unit] section, which
394                 carries generic information about the unit that is not
395                 dependent on the type of unit:</para>
396
397                 <variablelist class='unit-directives'>
398
399                         <varlistentry>
400                                 <term><varname>Description=</varname></term>
401                                 <listitem><para>A free-form string
402                                 describing the unit. This is intended
403                                 for use in UIs to show descriptive
404                                 information along with the unit
405                                 name. The description should contain a name
406                                 that means something to the end user.
407                                 <literal>Apache2 Web Server</literal> is a good
408                                 example. Bad examples are
409                                 <literal>high-performance light-weight HTTP
410                                 server</literal> (too generic) or
411                                 <literal>Apache2</literal> (too specific and
412                                 meaningless for people who do not know
413                                 Apache).</para></listitem>
414                         </varlistentry>
415
416                         <varlistentry>
417                                 <term><varname>Documentation=</varname></term>
418                                 <listitem><para>A space-separated list
419                                 of URIs referencing documentation for
420                                 this unit or its
421                                 configuration. Accepted are only URIs
422                                 of the types
423                                 <literal>http://</literal>,
424                                 <literal>https://</literal>,
425                                 <literal>file:</literal>,
426                                 <literal>info:</literal>,
427                                 <literal>man:</literal>. For more
428                                 information about the syntax of these
429                                 URIs, see
430                                 <citerefentry project='man-pages'><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
431                                 URIs should be listed in order of
432                                 relevance, starting with the most
433                                 relevant. It is a good idea to first
434                                 reference documentation that explains
435                                 what the unit's purpose is, followed
436                                 by how it is configured, followed by
437                                 any other related documentation. This
438                                 option may be specified more than once,
439                                 in which case the specified list of
440                                 URIs is merged. If the empty string is
441                                 assigned to this option, the list is
442                                 reset and all prior assignments will
443                                 have no effect.</para></listitem>
444                         </varlistentry>
445
446                         <varlistentry>
447                                 <term><varname>Requires=</varname></term>
448
449                                 <listitem><para>Configures requirement
450                                 dependencies on other units. If this
451                                 unit gets activated, the units listed
452                                 here will be activated as well. If one
453                                 of the other units gets deactivated or
454                                 its activation fails, this unit will
455                                 be deactivated. This option may be
456                                 specified more than once or multiple
457                                 space-separated units may be specified
458                                 in one option in which case
459                                 requirement dependencies for all
460                                 listed names will be created. Note
461                                 that requirement dependencies do not
462                                 influence the order in which services
463                                 are started or stopped. This has to be
464                                 configured independently with the
465                                 <varname>After=</varname> or
466                                 <varname>Before=</varname> options. If
467                                 a unit
468                                 <filename>foo.service</filename>
469                                 requires a unit
470                                 <filename>bar.service</filename> as
471                                 configured with
472                                 <varname>Requires=</varname> and no
473                                 ordering is configured with
474                                 <varname>After=</varname> or
475                                 <varname>Before=</varname>, then both
476                                 units will be started simultaneously
477                                 and without any delay between them if
478                                 <filename>foo.service</filename> is
479                                 activated. Often it is a better choice
480                                 to use <varname>Wants=</varname>
481                                 instead of
482                                 <varname>Requires=</varname> in order
483                                 to achieve a system that is more
484                                 robust when dealing with failing
485                                 services.</para>
486
487                                 <para>Note that dependencies of this
488                                 type may also be configured outside of
489                                 the unit configuration file by
490                                 adding a symlink to a
491                                 <filename>.requires/</filename> directory
492                                 accompanying the unit file. For
493                                 details see above.</para></listitem>
494                         </varlistentry>
495
496                         <varlistentry>
497                                 <term><varname>RequiresOverridable=</varname></term>
498
499                                 <listitem><para>Similar to
500                                 <varname>Requires=</varname>.
501                                 Dependencies listed in
502                                 <varname>RequiresOverridable=</varname>
503                                 which cannot be fulfilled or fail to
504                                 start are ignored if the startup was
505                                 explicitly requested by the user. If
506                                 the start-up was pulled in indirectly
507                                 by some dependency or automatic
508                                 start-up of units that is not
509                                 requested by the user, this dependency
510                                 must be fulfilled and otherwise the
511                                 transaction fails. Hence, this option
512                                 may be used to configure dependencies
513                                 that are normally honored unless the
514                                 user explicitly starts up the unit, in
515                                 which case whether they failed or not
516                                 is irrelevant.</para></listitem>
517
518                         </varlistentry>
519                         <varlistentry>
520                                 <term><varname>Requisite=</varname></term>
521                                 <term><varname>RequisiteOverridable=</varname></term>
522
523                                 <listitem><para>Similar to
524                                 <varname>Requires=</varname> and
525                                 <varname>RequiresOverridable=</varname>,
526                                 respectively. However, if the units
527                                 listed here are not started already,
528                                 they will not be started and the
529                                 transaction will fail immediately.
530                                 </para></listitem>
531                         </varlistentry>
532
533                         <varlistentry>
534                                 <term><varname>Wants=</varname></term>
535
536                                 <listitem><para>A weaker version of
537                                 <varname>Requires=</varname>. Units
538                                 listed in this option will be started
539                                 if the configuring unit is. However,
540                                 if the listed units fail to start
541                                 or cannot be added to the transaction,
542                                 this has no impact on the validity of
543                                 the transaction as a whole. This is
544                                 the recommended way to hook start-up
545                                 of one unit to the start-up of another
546                                 unit.</para>
547
548                                 <para>Note that dependencies of this
549                                 type may also be configured outside of
550                                 the unit configuration file by adding
551                                 symlinks to a
552                                 <filename>.wants/</filename> directory
553                                 accompanying the unit file. For
554                                 details, see above.</para></listitem>
555                         </varlistentry>
556
557                         <varlistentry>
558                                 <term><varname>BindsTo=</varname></term>
559
560                                 <listitem><para>Configures requirement
561                                 dependencies, very similar in style to
562                                 <varname>Requires=</varname>, however
563                                 in addition to this behavior, it also
564                                 declares that this unit is stopped
565                                 when any of the units listed suddenly
566                                 disappears. Units can suddenly,
567                                 unexpectedly disappear if a service
568                                 terminates on its own choice, a device
569                                 is unplugged or a mount point
570                                 unmounted without involvement of
571                                 systemd.</para></listitem>
572                         </varlistentry>
573
574                         <varlistentry>
575                                 <term><varname>PartOf=</varname></term>
576
577                                 <listitem><para>Configures dependencies
578                                 similar to <varname>Requires=</varname>,
579                                 but limited to stopping and restarting
580                                 of units. When systemd stops or restarts
581                                 the units listed here, the action is
582                                 propagated to this unit.
583                                 Note that this is a one-way dependency —
584                                 changes to this unit do not affect the
585                                 listed units.
586                                 </para></listitem>
587                         </varlistentry>
588
589                         <varlistentry>
590                                 <term><varname>Conflicts=</varname></term>
591
592                                 <listitem><para>A space-separated list
593                                 of unit names. Configures negative
594                                 requirement dependencies. If a unit
595                                 has a <varname>Conflicts=</varname>
596                                 setting on another unit, starting the
597                                 former will stop the latter and vice
598                                 versa. Note that this setting is
599                                 independent of and orthogonal to the
600                                 <varname>After=</varname> and
601                                 <varname>Before=</varname> ordering
602                                 dependencies.</para>
603
604                                 <para>If a unit A that conflicts with
605                                 a unit B is scheduled to be started at
606                                 the same time as B, the transaction
607                                 will either fail (in case both are
608                                 required part of the transaction) or
609                                 be modified to be fixed (in case one
610                                 or both jobs are not a required part
611                                 of the transaction). In the latter
612                                 case, the job that is not the required
613                                 will be removed, or in case both are
614                                 not required, the unit that conflicts
615                                 will be started and the unit that is
616                                 conflicted is
617                                 stopped.</para></listitem>
618                         </varlistentry>
619
620                         <varlistentry>
621                                 <term><varname>Before=</varname></term>
622                                 <term><varname>After=</varname></term>
623
624                                 <listitem><para>A space-separated list
625                                 of unit names. Configures ordering
626                                 dependencies between units. If a unit
627                                 <filename>foo.service</filename>
628                                 contains a setting
629                                 <option>Before=bar.service</option>
630                                 and both units are being started,
631                                 <filename>bar.service</filename>'s
632                                 start-up is delayed until
633                                 <filename>foo.service</filename> is
634                                 started up. Note that this setting is
635                                 independent of and orthogonal to the
636                                 requirement dependencies as configured
637                                 by <varname>Requires=</varname>. It is
638                                 a common pattern to include a unit
639                                 name in both the
640                                 <varname>After=</varname> and
641                                 <varname>Requires=</varname> option, in
642                                 which case the unit listed will be
643                                 started before the unit that is
644                                 configured with these options. This
645                                 option may be specified more than
646                                 once, in which case ordering
647                                 dependencies for all listed names are
648                                 created. <varname>After=</varname> is
649                                 the inverse of
650                                 <varname>Before=</varname>, i.e. while
651                                 <varname>After=</varname> ensures that
652                                 the configured unit is started after
653                                 the listed unit finished starting up,
654                                 <varname>Before=</varname> ensures the
655                                 opposite, i.e.  that the configured
656                                 unit is fully started up before the
657                                 listed unit is started. Note that when
658                                 two units with an ordering dependency
659                                 between them are shut down, the
660                                 inverse of the start-up order is
661                                 applied. i.e. if a unit is configured
662                                 with <varname>After=</varname> on
663                                 another unit, the former is stopped
664                                 before the latter if both are shut
665                                 down. If one unit with an ordering
666                                 dependency on another unit is shut
667                                 down while the latter is started up,
668                                 the shut down is ordered before the
669                                 start-up regardless of whether the
670                                 ordering dependency is actually of
671                                 type <varname>After=</varname> or
672                                 <varname>Before=</varname>. If two
673                                 units have no ordering dependencies
674                                 between them, they are shut down or
675                                 started up simultaneously, and no
676                                 ordering takes
677                                 place. </para></listitem>
678                         </varlistentry>
679
680                         <varlistentry>
681                                 <term><varname>OnFailure=</varname></term>
682
683                                 <listitem><para>A space-separated list
684                                 of one or more units that are
685                                 activated when this unit enters the
686                                 <literal>failed</literal>
687                                 state.</para></listitem>
688                         </varlistentry>
689
690                         <varlistentry>
691                                 <term><varname>PropagatesReloadTo=</varname></term>
692                                 <term><varname>ReloadPropagatedFrom=</varname></term>
693
694                                 <listitem><para>A space-separated list
695                                 of one or more units where reload
696                                 requests on this unit will be
697                                 propagated to, or reload requests on
698                                 the other unit will be propagated to
699                                 this unit, respectively. Issuing a
700                                 reload request on a unit will
701                                 automatically also enqueue a reload
702                                 request on all units that the reload
703                                 request shall be propagated to via
704                                 these two settings.</para></listitem>
705                         </varlistentry>
706
707                         <varlistentry>
708                                 <term><varname>JoinsNamespaceOf=</varname></term>
709
710                                 <listitem><para>For units that start
711                                 processes (such as service units),
712                                 lists one or more other units whose
713                                 network and/or temporary file
714                                 namespace to join. This only applies
715                                 to unit types which support the
716                                 <varname>PrivateNetwork=</varname> and
717                                 <varname>PrivateTmp=</varname>
718                                 directives (see
719                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
720                                 for details). If a unit that has this
721                                 setting set is started, its processes
722                                 will see the same
723                                 <filename>/tmp</filename>,
724                                 <filename>/tmp/var</filename> and
725                                 network namespace as one listed unit
726                                 that is started. If multiple listed
727                                 units are already started, it is not
728                                 defined which namespace is
729                                 joined. Note that this setting only
730                                 has an effect if
731                                 <varname>PrivateNetwork=</varname>
732                                 and/or <varname>PrivateTmp=</varname>
733                                 is enabled for both the unit that
734                                 joins the namespace and the unit whose
735                                 namespace is joined.</para></listitem>
736                         </varlistentry>
737
738                         <varlistentry>
739                                 <term><varname>RequiresMountsFor=</varname></term>
740
741                                 <listitem><para>Takes a
742                                 space-separated list of absolute
743                                 paths. Automatically adds dependencies
744                                 of type <varname>Requires=</varname>
745                                 and <varname>After=</varname> for all
746                                 mount units required to access the
747                                 specified path.</para>
748
749                                 <para>Mount points marked with
750                                 <option>noauto</option> are not
751                                 mounted automatically and will be
752                                 ignored for the purposes of this
753                                 option. If such a mount should be a
754                                 requirement for this unit,
755                                 direct dependencies on the mount
756                                 units may be added
757                                 (<varname>Requires=</varname> and
758                                 <varname>After=</varname> or
759                                 some other combination).
760                                 </para></listitem>
761                         </varlistentry>
762
763                         <varlistentry>
764                                 <term><varname>OnFailureJobMode=</varname></term>
765
766                                 <listitem><para>Takes a value of
767                                 <literal>fail</literal>,
768                                 <literal>replace</literal>,
769                                 <literal>replace-irreversibly</literal>,
770                                 <literal>isolate</literal>,
771                                 <literal>flush</literal>,
772                                 <literal>ignore-dependencies</literal>
773                                 or
774                                 <literal>ignore-requirements</literal>. Defaults
775                                 to
776                                 <literal>replace</literal>. Specifies
777                                 how the units listed in
778                                 <varname>OnFailure=</varname> will be
779                                 enqueued. See
780                                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
781                                 <option>--job-mode=</option> option
782                                 for details on the possible values. If
783                                 this is set to
784                                 <literal>isolate</literal>, only a
785                                 single unit may be listed in
786                                 <varname>OnFailure=</varname>..</para></listitem>
787                         </varlistentry>
788
789                         <varlistentry>
790                                 <term><varname>IgnoreOnIsolate=</varname></term>
791
792                                 <listitem><para>Takes a boolean
793                                 argument. If <option>true</option>,
794                                 this unit will not be stopped when
795                                 isolating another unit. Defaults to
796                                 <option>false</option>.</para></listitem>
797                         </varlistentry>
798
799                         <varlistentry>
800                                 <term><varname>IgnoreOnSnapshot=</varname></term>
801
802                                 <listitem><para>Takes a boolean
803                                 argument. If <option>true</option>,
804                                 this unit will not be included in
805                                 snapshots. Defaults to
806                                 <option>true</option> for device and
807                                 snapshot units, <option>false</option>
808                                 for the others.</para></listitem>
809                         </varlistentry>
810
811                         <varlistentry>
812                                 <term><varname>StopWhenUnneeded=</varname></term>
813
814                                 <listitem><para>Takes a boolean
815                                 argument. If <option>true</option>,
816                                 this unit will be stopped when it is
817                                 no longer used. Note that in order to
818                                 minimize the work to be executed,
819                                 systemd will not stop units by default
820                                 unless they are conflicting with other
821                                 units, or the user explicitly
822                                 requested their shut down. If this
823                                 option is set, a unit will be
824                                 automatically cleaned up if no other
825                                 active unit requires it. Defaults to
826                                 <option>false</option>.</para></listitem>
827                         </varlistentry>
828
829                         <varlistentry>
830                                 <term><varname>RefuseManualStart=</varname></term>
831                                 <term><varname>RefuseManualStop=</varname></term>
832
833                                 <listitem><para>Takes a boolean
834                                 argument. If <option>true</option>,
835                                 this unit can only be activated
836                                 or deactivated indirectly. In
837                                 this case, explicit start-up
838                                 or termination requested by the
839                                 user is denied, however if it is
840                                 started or stopped as a
841                                 dependency of another unit, start-up
842                                 or termination will succeed. This
843                                 is mostly a safety feature to ensure
844                                 that the user does not accidentally
845                                 activate units that are not intended
846                                 to be activated explicitly, and not
847                                 accidentally deactivate units that are
848                                 not intended to be deactivated.
849                                 These options default to
850                                 <option>false</option>.</para></listitem>
851                         </varlistentry>
852
853                         <varlistentry>
854                                 <term><varname>AllowIsolate=</varname></term>
855
856                                 <listitem><para>Takes a boolean
857                                 argument. If <option>true</option>,
858                                 this unit may be used with the
859                                 <command>systemctl isolate</command>
860                                 command. Otherwise, this will be
861                                 refused. It probably is a good idea to
862                                 leave this disabled except for target
863                                 units that shall be used similar to
864                                 runlevels in SysV init systems, just
865                                 as a precaution to avoid unusable
866                                 system states. This option defaults to
867                                 <option>false</option>.</para></listitem>
868                         </varlistentry>
869
870                         <varlistentry>
871                                 <term><varname>DefaultDependencies=</varname></term>
872
873                                 <listitem><para>Takes a boolean
874                                 argument. If <option>true</option>,
875                                 (the default), a few default
876                                 dependencies will implicitly be
877                                 created for the unit. The actual
878                                 dependencies created depend on the
879                                 unit type. For example, for service
880                                 units, these dependencies ensure that
881                                 the service is started only after
882                                 basic system initialization is
883                                 completed and is properly terminated on
884                                 system shutdown. See the respective
885                                 man pages for details. Generally, only
886                                 services involved with early boot or
887                                 late shutdown should set this option
888                                 to <option>false</option>. It is
889                                 highly recommended to leave this
890                                 option enabled for the majority of
891                                 common units. If set to
892                                 <option>false</option>, this option
893                                 does not disable all implicit
894                                 dependencies, just non-essential
895                                 ones.</para></listitem>
896                         </varlistentry>
897
898                         <varlistentry>
899                                 <term><varname>JobTimeoutSec=</varname></term>
900                                 <term><varname>JobTimeoutAction=</varname></term>
901                                 <term><varname>JobTimeoutRebootArgument=</varname></term>
902
903                                 <listitem><para>When a job for this
904                                 unit is queued a time-out may be
905                                 configured. If this time limit is
906                                 reached, the job will be cancelled,
907                                 the unit however will not change state
908                                 or even enter the
909                                 <literal>failed</literal> mode. This
910                                 value defaults to 0 (job timeouts
911                                 disabled), except for device
912                                 units. NB: this timeout is independent
913                                 from any unit-specific timeout (for
914                                 example, the timeout set with
915                                 <varname>StartTimeoutSec=</varname> in service
916                                 units) as the job timeout has no
917                                 effect on the unit itself, only on the
918                                 job that might be pending for it. Or
919                                 in other words: unit-specific timeouts
920                                 are useful to abort unit state
921                                 changes, and revert them. The job
922                                 timeout set with this option however
923                                 is useful to abort only the job
924                                 waiting for the unit state to
925                                 change.</para>
926
927                                 <para><varname>JobTimeoutAction=</varname>
928                                 optionally configures an additional
929                                 action to take when the time-out is
930                                 hit. It takes the same values as the
931                                 per-service
932                                 <varname>StartLimitAction=</varname>
933                                 setting, see
934                                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
935                                 for details. Defaults to
936                                 <option>none</option>. <varname>JobTimeoutRebootArgument=</varname>
937                                 configures an optional reboot string
938                                 to pass to the
939                                 <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
940                                 system call.</para></listitem>
941                         </varlistentry>
942
943                         <varlistentry>
944                                 <term><varname>ConditionArchitecture=</varname></term>
945                                 <term><varname>ConditionVirtualization=</varname></term>
946                                 <term><varname>ConditionHost=</varname></term>
947                                 <term><varname>ConditionKernelCommandLine=</varname></term>
948                                 <term><varname>ConditionSecurity=</varname></term>
949                                 <term><varname>ConditionCapability=</varname></term>
950                                 <term><varname>ConditionACPower=</varname></term>
951                                 <term><varname>ConditionNeedsUpdate=</varname></term>
952                                 <term><varname>ConditionFirstBoot=</varname></term>
953                                 <term><varname>ConditionPathExists=</varname></term>
954                                 <term><varname>ConditionPathExistsGlob=</varname></term>
955                                 <term><varname>ConditionPathIsDirectory=</varname></term>
956                                 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
957                                 <term><varname>ConditionPathIsMountPoint=</varname></term>
958                                 <term><varname>ConditionPathIsReadWrite=</varname></term>
959                                 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
960                                 <term><varname>ConditionFileNotEmpty=</varname></term>
961                                 <term><varname>ConditionFileIsExecutable=</varname></term>
962
963                                 <!-- We don't document ConditionNull=
964                                      here as it is not particularly
965                                      useful and probably just
966                                      confusing. -->
967
968                                 <listitem><para>Before starting a unit
969                                 verify that the specified condition is
970                                 true. If it is not true, the starting
971                                 of the unit will be skipped, however
972                                 all ordering dependencies of it are
973                                 still respected. A failing condition
974                                 will not result in the unit being
975                                 moved into a failure state. The
976                                 condition is checked at the time the
977                                 queued start job is to be
978                                 executed.</para>
979
980                                 <para><varname>ConditionArchitecture=</varname>
981                                 may be used to check whether the
982                                 system is running on a specific
983                                 architecture. Takes one of
984                                 <varname>x86</varname>,
985                                 <varname>x86-64</varname>,
986                                 <varname>ppc</varname>,
987                                 <varname>ppc-le</varname>,
988                                 <varname>ppc64</varname>,
989                                 <varname>ppc64-le</varname>,
990                                 <varname>ia64</varname>,
991                                 <varname>parisc</varname>,
992                                 <varname>parisc64</varname>,
993                                 <varname>s390</varname>,
994                                 <varname>s390x</varname>,
995                                 <varname>sparc</varname>,
996                                 <varname>sparc64</varname>,
997                                 <varname>mips</varname>,
998                                 <varname>mips-le</varname>,
999                                 <varname>mips64</varname>,
1000                                 <varname>mips64-le</varname>,
1001                                 <varname>alpha</varname>,
1002                                 <varname>arm</varname>,
1003                                 <varname>arm-be</varname>,
1004                                 <varname>arm64</varname>,
1005                                 <varname>arm64-be</varname>,
1006                                 <varname>sh</varname>,
1007                                 <varname>sh64</varname>,
1008                                 <varname>m86k</varname>,
1009                                 <varname>tilegx</varname>,
1010                                 <varname>cris</varname> to test
1011                                 against a specific architecture. The
1012                                 architecture is determined from the
1013                                 information returned by
1014                                 <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1015                                 and is thus subject to
1016                                 <citerefentry><refentrytitle>personality</refentrytitle><manvolnum>2</manvolnum></citerefentry>. Note
1017                                 that a <varname>Personality=</varname>
1018                                 setting in the same unit file has no
1019                                 effect on this condition. A special
1020                                 architecture name
1021                                 <varname>native</varname> is mapped to
1022                                 the architecture the system manager
1023                                 itself is compiled for. The test may
1024                                 be negated by prepending an
1025                                 exclamation mark.</para>
1026
1027                                 <para><varname>ConditionVirtualization=</varname>
1028                                 may be used to check whether the
1029                                 system is executed in a virtualized
1030                                 environment and optionally test
1031                                 whether it is a specific
1032                                 implementation. Takes either boolean
1033                                 value to check if being executed in
1034                                 any virtualized environment, or one of
1035                                 <varname>vm</varname> and
1036                                 <varname>container</varname> to test
1037                                 against a generic type of
1038                                 virtualization solution, or one of
1039                                 <varname>qemu</varname>,
1040                                 <varname>kvm</varname>,
1041                                 <varname>zvm</varname>,
1042                                 <varname>vmware</varname>,
1043                                 <varname>microsoft</varname>,
1044                                 <varname>oracle</varname>,
1045                                 <varname>xen</varname>,
1046                                 <varname>bochs</varname>,
1047                                 <varname>uml</varname>,
1048                                 <varname>openvz</varname>,
1049                                 <varname>lxc</varname>,
1050                                 <varname>lxc-libvirt</varname>,
1051                                 <varname>systemd-nspawn</varname>,
1052                                 <varname>docker</varname> to test
1053                                 against a specific implementation. See
1054                                 <citerefentry><refentrytitle>systemd-detect-virt</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1055                                 for a full list of known
1056                                 virtualization technologies and their
1057                                 identifiers. If multiple
1058                                 virtualization technologies are
1059                                 nested, only the innermost is
1060                                 considered. The test may be negated by
1061                                 prepending an exclamation mark.</para>
1062
1063                                 <para><varname>ConditionHost=</varname>
1064                                 may be used to match against the
1065                                 hostname or machine ID of the
1066                                 host. This either takes a hostname
1067                                 string (optionally with shell style
1068                                 globs) which is tested against the
1069                                 locally set hostname as returned by
1070                                 <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
1071                                 or a machine ID formatted as string
1072                                 (see
1073                                 <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
1074                                 The test may be negated by prepending
1075                                 an exclamation mark.</para>
1076
1077                                 <para><varname>ConditionKernelCommandLine=</varname>
1078                                 may be used to check whether a
1079                                 specific kernel command line option is
1080                                 set (or if prefixed with the
1081                                 exclamation mark unset). The argument
1082                                 must either be a single word, or an
1083                                 assignment (i.e. two words, separated
1084                                 <literal>=</literal>). In the former
1085                                 case the kernel command line is
1086                                 searched for the word appearing as is,
1087                                 or as left hand side of an
1088                                 assignment. In the latter case, the
1089                                 exact assignment is looked for with
1090                                 right and left hand side
1091                                 matching.</para>
1092
1093                                 <para><varname>ConditionSecurity=</varname>
1094                                 may be used to check whether the given
1095                                 security module is enabled on the
1096                                 system. Currently the recognized
1097                                 values values are
1098                                 <varname>selinux</varname>,
1099                                 <varname>apparmor</varname>,
1100                                 <varname>ima</varname>,
1101                                 <varname>smack</varname> and
1102                                 <varname>audit</varname>. The test may
1103                                 be negated by prepending an
1104                                 exclamation mark.</para>
1105
1106                                 <para><varname>ConditionCapability=</varname>
1107                                 may be used to check whether the given
1108                                 capability exists in the capability
1109                                 bounding set of the service manager
1110                                 (i.e. this does not check whether
1111                                 capability is actually available in
1112                                 the permitted or effective sets, see
1113                                 <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1114                                 for details). Pass a capability name
1115                                 such as <literal>CAP_MKNOD</literal>,
1116                                 possibly prefixed with an exclamation
1117                                 mark to negate the check.</para>
1118
1119                                 <para><varname>ConditionACPower=</varname>
1120                                 may be used to check whether the
1121                                 system has AC power, or is exclusively
1122                                 battery powered at the time of
1123                                 activation of the unit. This takes a
1124                                 boolean argument. If set to
1125                                 <varname>true</varname>, the condition
1126                                 will hold only if at least one AC
1127                                 connector of the system is connected
1128                                 to a power source, or if no AC
1129                                 connectors are known. Conversely, if
1130                                 set to <varname>false</varname>, the
1131                                 condition will hold only if there is
1132                                 at least one AC connector known and
1133                                 all AC connectors are disconnected
1134                                 from a power source.</para>
1135
1136                                 <para><varname>ConditionNeedsUpdate=</varname>
1137                                 takes one of <filename>/var</filename>
1138                                 or <filename>/etc</filename> as
1139                                 argument, possibly prefixed with a
1140                                 <literal>!</literal> (for inverting
1141                                 the condition). This condition may be
1142                                 used to conditionalize units on
1143                                 whether the specified directory
1144                                 requires an update because
1145                                 <filename>/usr</filename>'s
1146                                 modification time is newer than the
1147                                 stamp file
1148                                 <filename>.updated</filename> in the
1149                                 specified directory. This is useful to
1150                                 implement offline updates of the
1151                                 vendor operating system resources in
1152                                 <filename>/usr</filename> that require
1153                                 updating of <filename>/etc</filename>
1154                                 or <filename>/var</filename> on the
1155                                 next following boot. Units making use
1156                                 of this condition should order
1157                                 themselves before
1158                                 <citerefentry><refentrytitle>systemd-update-done.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1159                                 to make sure they run before the stamp
1160                                 files's modification time gets reset
1161                                 indicating a completed update.</para>
1162
1163                                 <para><varname>ConditionFirstBoot=</varname>
1164                                 takes a boolean argument. This
1165                                 condition may be used to
1166                                 conditionalize units on whether the
1167                                 system is booting up with an
1168                                 unpopulated <filename>/etc</filename>
1169                                 directory. This may be used to
1170                                 populate <filename>/etc</filename> on
1171                                 the first boot after factory reset, or
1172                                 when a new system instances boots up
1173                                 for the first time.</para>
1174
1175                                 <para>With
1176                                 <varname>ConditionPathExists=</varname>
1177                                 a file existence condition is
1178                                 checked before a unit is started. If
1179                                 the specified absolute path name does
1180                                 not exist, the condition will
1181                                 fail. If the absolute path name passed
1182                                 to
1183                                 <varname>ConditionPathExists=</varname>
1184                                 is prefixed with an exclamation mark
1185                                 (<literal>!</literal>), the test is negated, and the unit
1186                                 is only started if the path does not
1187                                 exist.</para>
1188
1189                                 <para><varname>ConditionPathExistsGlob=</varname>
1190                                 is similar to
1191                                 <varname>ConditionPathExists=</varname>,
1192                                 but checks for the existence of at
1193                                 least one file or directory matching
1194                                 the specified globbing pattern.</para>
1195
1196                                 <para><varname>ConditionPathIsDirectory=</varname>
1197                                 is similar to
1198                                 <varname>ConditionPathExists=</varname>
1199                                 but verifies whether a certain path
1200                                 exists and is a
1201                                 directory.</para>
1202
1203                                 <para><varname>ConditionPathIsSymbolicLink=</varname>
1204                                 is similar to
1205                                 <varname>ConditionPathExists=</varname>
1206                                 but verifies whether a certain path
1207                                 exists and is a symbolic
1208                                 link.</para>
1209
1210                                 <para><varname>ConditionPathIsMountPoint=</varname>
1211                                 is similar to
1212                                 <varname>ConditionPathExists=</varname>
1213                                 but verifies whether a certain path
1214                                 exists and is a mount
1215                                 point.</para>
1216
1217                                 <para><varname>ConditionPathIsReadWrite=</varname>
1218                                 is similar to
1219                                 <varname>ConditionPathExists=</varname>
1220                                 but verifies whether the underlying
1221                                 file system is readable and writable
1222                                 (i.e. not mounted
1223                                 read-only).</para>
1224
1225                                 <para><varname>ConditionDirectoryNotEmpty=</varname>
1226                                 is similar to
1227                                 <varname>ConditionPathExists=</varname>
1228                                 but verifies whether a certain path
1229                                 exists and is a non-empty
1230                                 directory.</para>
1231
1232                                 <para><varname>ConditionFileNotEmpty=</varname>
1233                                 is similar to
1234                                 <varname>ConditionPathExists=</varname>
1235                                 but verifies whether a certain path
1236                                 exists and refers to a regular file
1237                                 with a non-zero size.</para>
1238
1239                                 <para><varname>ConditionFileIsExecutable=</varname>
1240                                 is similar to
1241                                 <varname>ConditionPathExists=</varname>
1242                                 but verifies whether a certain path
1243                                 exists, is a regular file and marked
1244                                 executable.</para>
1245
1246                                 <para>If multiple conditions are
1247                                 specified, the unit will be executed if
1248                                 all of them apply (i.e. a logical AND
1249                                 is applied). Condition checks can be
1250                                 prefixed with a pipe symbol (|) in
1251                                 which case a condition becomes a
1252                                 triggering condition. If at least one
1253                                 triggering condition is defined for a
1254                                 unit, then the unit will be executed if
1255                                 at least one of the triggering
1256                                 conditions apply and all of the
1257                                 non-triggering conditions. If you
1258                                 prefix an argument with the pipe
1259                                 symbol and an exclamation mark, the
1260                                 pipe symbol must be passed first, the
1261                                 exclamation second. Except for
1262                                 <varname>ConditionPathIsSymbolicLink=</varname>,
1263                                 all path checks follow symlinks. If
1264                                 any of these options is assigned the
1265                                 empty string, the list of conditions is
1266                                 reset completely, all previous
1267                                 condition settings (of any kind) will
1268                                 have no effect.</para></listitem>
1269                         </varlistentry>
1270
1271                         <varlistentry>
1272                                 <term><varname>AssertArchitecture=</varname></term>
1273                                 <term><varname>AssertVirtualization=</varname></term>
1274                                 <term><varname>AssertHost=</varname></term>
1275                                 <term><varname>AssertKernelCommandLine=</varname></term>
1276                                 <term><varname>AssertSecurity=</varname></term>
1277                                 <term><varname>AssertCapability=</varname></term>
1278                                 <term><varname>AssertACPower=</varname></term>
1279                                 <term><varname>AssertNeedsUpdate=</varname></term>
1280                                 <term><varname>AssertFirstBoot=</varname></term>
1281                                 <term><varname>AssertPathExists=</varname></term>
1282                                 <term><varname>AssertPathExistsGlob=</varname></term>
1283                                 <term><varname>AssertPathIsDirectory=</varname></term>
1284                                 <term><varname>AssertPathIsSymbolicLink=</varname></term>
1285                                 <term><varname>AssertPathIsMountPoint=</varname></term>
1286                                 <term><varname>AssertPathIsReadWrite=</varname></term>
1287                                 <term><varname>AssertDirectoryNotEmpty=</varname></term>
1288                                 <term><varname>AssertFileNotEmpty=</varname></term>
1289                                 <term><varname>AssertFileIsExecutable=</varname></term>
1290
1291                                 <listitem><para>Similar to the
1292                                 <varname>ConditionArchitecture=</varname>,
1293                                 <varname>ConditionVirtualization=</varname>,
1294                                 ... condition settings described above
1295                                 these settings add assertion checks to
1296                                 the start-up of the unit. However,
1297                                 unlike the conditions settings any
1298                                 assertion setting that is not met
1299                                 results in failure of the start
1300                                 job it was triggered by.</para></listitem>
1301                         </varlistentry>
1302
1303                         <varlistentry>
1304                                 <term><varname>SourcePath=</varname></term>
1305                                 <listitem><para>A path to a
1306                                 configuration file this unit has been
1307                                 generated from. This is primarily
1308                                 useful for implementation of generator
1309                                 tools that convert configuration from
1310                                 an external configuration file format
1311                                 into native unit files. This
1312                                 functionality should not be used in
1313                                 normal units.</para></listitem>
1314                         </varlistentry>
1315                 </variablelist>
1316
1317         </refsect1>
1318
1319         <refsect1>
1320                 <title>[Install] Section Options</title>
1321
1322                 <para>Unit file may include an
1323                 <literal>[Install]</literal> section, which carries
1324                 installation information for the unit. This section is
1325                 not interpreted by
1326                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1327                 during runtime. It is used exclusively by the
1328                 <command>enable</command> and
1329                 <command>disable</command> commands of the
1330                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1331                 tool during installation of a unit:</para>
1332
1333                 <variablelist class='unit-directives'>
1334                         <varlistentry>
1335                                 <term><varname>Alias=</varname></term>
1336
1337                                 <listitem><para>A space-separated list
1338                                 of additional names this unit shall be
1339                                 installed under. The names listed here
1340                                 must have the same suffix (i.e. type)
1341                                 as the unit file name. This option may
1342                                 be specified more than once, in which
1343                                 case all listed names are used. At
1344                                 installation time, <command>systemctl
1345                                 enable</command> will create symlinks
1346                                 from these names to the unit
1347                                 filename.</para></listitem>
1348                         </varlistentry>
1349
1350                         <varlistentry>
1351                                 <term><varname>WantedBy=</varname></term>
1352                                 <term><varname>RequiredBy=</varname></term>
1353
1354                                 <listitem><para>This option may be
1355                                 used more than once, or a
1356                                 space-separated list of unit names may
1357                                 be given. A symbolic link is created
1358                                 in the <filename>.wants/</filename> or
1359                                 <filename>.requires/</filename>
1360                                 directory of each of the listed units
1361                                 when this unit is installed by
1362                                 <command>systemctl enable</command>.
1363                                 This has the effect that a dependency
1364                                 of type <varname>Wants=</varname> or
1365                                 <varname>Requires=</varname> is added
1366                                 from the listed unit to the current
1367                                 unit. The primary result is that the
1368                                 current unit will be started when the
1369                                 listed unit is started. See the
1370                                 description of
1371                                 <varname>Wants=</varname> and
1372                                 <varname>Requires=</varname> in the
1373                                 [Unit] section for details.</para>
1374
1375                                 <para><command>WantedBy=foo.service</command>
1376                                 in a service
1377                                 <filename>bar.service</filename> is
1378                                 mostly equivalent to
1379                                 <command>Alias=foo.service.wants/bar.service</command>
1380                                 in the same file. In case of template
1381                                 units, <command>systemctl enable</command>
1382                                 must be called with an instance name, and
1383                                 this instance will be added to the
1384                                 <filename>.wants/</filename> or
1385                                 <filename>.requires/</filename> list
1386                                 of the listed unit.
1387                                 E.g. <command>WantedBy=getty.target</command>
1388                                 in a service
1389                                 <filename>getty@.service</filename>
1390                                 will result in <command>systemctl
1391                                 enable getty@tty2.service</command>
1392                                 creating a
1393                                 <filename>getty.target.wants/getty@tty2.service</filename>
1394                                 link to <filename>getty@.service</filename>.
1395                                 </para></listitem>
1396                         </varlistentry>
1397
1398                         <varlistentry>
1399                                 <term><varname>Also=</varname></term>
1400
1401                                 <listitem><para>Additional units to
1402                                 install/deinstall when this unit is
1403                                 installed/deinstalled. If the user
1404                                 requests installation/deinstallation
1405                                 of a unit with this option configured,
1406                                 <command>systemctl enable</command>
1407                                 and <command>systemctl
1408                                 disable</command> will automatically
1409                                 install/uninstall units listed in this option as
1410                                 well.</para>
1411
1412                                 <para>This option may be used more
1413                                 than once, or a space-separated list
1414                                 of unit names may be
1415                                 given.</para></listitem>
1416                         </varlistentry>
1417
1418                         <varlistentry>
1419                                 <term><varname>DefaultInstance=</varname></term>
1420
1421                                 <listitem><para>In template unit files,
1422                                 this specifies for which instance the
1423                                 unit shall be enabled if the template
1424                                 is enabled without any explicitly set
1425                                 instance. This option has no effect in
1426                                 non-template unit files. The specified
1427                                 string must be usable as instance
1428                                 identifier.</para></listitem>
1429                         </varlistentry>
1430                 </variablelist>
1431
1432                 <para>The following specifiers are interpreted in the
1433                 Install section: %n, %N, %p, %i, %U, %u, %m, %H, %b, %v.
1434                 For their meaning see the next section.
1435                 </para>
1436         </refsect1>
1437
1438         <refsect1>
1439                 <title>Specifiers</title>
1440
1441                 <para>Many settings resolve specifiers which may be
1442                 used to write generic unit files referring to runtime
1443                 or unit parameters that are replaced when the unit
1444                 files are loaded. The following specifiers are
1445                 understood:</para>
1446
1447                 <table>
1448                   <title>Specifiers available in unit files</title>
1449                   <tgroup cols='3' align='left' colsep='1' rowsep='1'>
1450                     <colspec colname="spec" />
1451                     <colspec colname="mean" />
1452                     <colspec colname="detail" />
1453                     <thead>
1454                       <row>
1455                         <entry>Specifier</entry>
1456                         <entry>Meaning</entry>
1457                         <entry>Details</entry>
1458                       </row>
1459                     </thead>
1460                     <tbody>
1461                       <row>
1462                         <entry><literal>%n</literal></entry>
1463                         <entry>Full unit name</entry>
1464                         <entry></entry>
1465                       </row>
1466                       <row>
1467                         <entry><literal>%N</literal></entry>
1468                         <entry>Unescaped full unit name</entry>
1469                         <entry>Same as <literal>%n</literal>, but with escaping undone</entry>
1470                       </row>
1471                       <row>
1472                         <entry><literal>%p</literal></entry>
1473                         <entry>Prefix name</entry>
1474                         <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>
1475                       </row>
1476                       <row>
1477                         <entry><literal>%P</literal></entry>
1478                         <entry>Unescaped prefix name</entry>
1479                         <entry>Same as <literal>%p</literal>, but with escaping undone</entry>
1480                       </row>
1481                       <row>
1482                         <entry><literal>%i</literal></entry>
1483                         <entry>Instance name</entry>
1484                         <entry>For instantiated units: this is the string between the <literal>@</literal> character and the suffix of the unit name.</entry>
1485                       </row>
1486                       <row>
1487                         <entry><literal>%I</literal></entry>
1488                         <entry>Unescaped instance name</entry>
1489                         <entry>Same as <literal>%i</literal>, but with escaping undone</entry>
1490                       </row>
1491                       <row>
1492                         <entry><literal>%f</literal></entry>
1493                         <entry>Unescaped filename</entry>
1494                         <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>
1495                       </row>
1496                       <row>
1497                         <entry><literal>%c</literal></entry>
1498                         <entry>Control group path of the unit</entry>
1499                         <entry>This path does not include the <filename>/sys/fs/cgroup/systemd/</filename> prefix.</entry>
1500                       </row>
1501                       <row>
1502                         <entry><literal>%r</literal></entry>
1503                         <entry>Control group path of the slice the unit is placed in</entry>
1504                         <entry>This usually maps to the parent cgroup path of <literal>%c</literal>.</entry>
1505                       </row>
1506                       <row>
1507                         <entry><literal>%R</literal></entry>
1508                         <entry>Root control group path below which slices and units are placed</entry>
1509                         <entry>For system instances, this resolves to <filename>/</filename>, except in containers, where this maps to the container's root control group path.</entry>
1510                       </row>
1511                       <row>
1512                         <entry><literal>%t</literal></entry>
1513                         <entry>Runtime directory</entry>
1514                         <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>
1515                       </row>
1516                       <row>
1517                         <entry><literal>%u</literal></entry>
1518                         <entry>User name</entry>
1519                         <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1520                       </row>
1521                       <row>
1522                         <entry><literal>%U</literal></entry>
1523                         <entry>User UID</entry>
1524                         <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>
1525                       </row>
1526                       <row>
1527                         <entry><literal>%h</literal></entry>
1528                         <entry>User home directory</entry>
1529                         <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>
1530                       </row>
1531                       <row>
1532                         <entry><literal>%s</literal></entry>
1533                         <entry>User shell</entry>
1534                         <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>
1535                       </row>
1536                       <row>
1537                         <entry><literal>%m</literal></entry>
1538                         <entry>Machine ID</entry>
1539                         <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>
1540                       </row>
1541                       <row>
1542                         <entry><literal>%b</literal></entry>
1543                         <entry>Boot ID</entry>
1544                         <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
1545                       </row>
1546                       <row>
1547                         <entry><literal>%H</literal></entry>
1548                         <entry>Host name</entry>
1549                         <entry>The hostname of the running system at the point in time the unit configuation is loaded.</entry>
1550                       </row>
1551                       <row>
1552                         <entry><literal>%v</literal></entry>
1553                         <entry>Kernel release</entry>
1554                         <entry>Identical to <command>uname -r</command> output</entry>
1555                       </row>
1556                       <row>
1557                         <entry><literal>%%</literal></entry>
1558                         <entry>Single percent sign</entry>
1559                         <entry>Use <literal>%%</literal> in place of <literal>%</literal> to specify a single percent sign.</entry>
1560                       </row>
1561                     </tbody>
1562                   </tgroup>
1563                 </table>
1564
1565                 <para>Please note that specifiers
1566                 <literal>%U</literal>, <literal>%h</literal>,
1567                 <literal>%s</literal> are mostly useless when systemd
1568                 is running in system mode.  PID 1 cannot query the
1569                 user account database for information, so the
1570                 specifiers only work as shortcuts for things which are
1571                 already specified in a different way in the unit
1572                 file. They are fully functional when systemd is
1573                 running in <option>--user</option> mode.</para>
1574         </refsect1>
1575
1576         <refsect1>
1577                 <title>See Also</title>
1578                 <para>
1579                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1580                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1581                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1582                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1583                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1584                         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1585                         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1586                         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1587                         <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1588                         <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1589                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1590                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1591                         <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1592                         <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1593                         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1594                         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1595                         <citerefentry><refentrytitle>systemd-analyze</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1596                         <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1597                         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1598                         <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1599                 </para>
1600         </refsect1>
1601
1602 </refentry>