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1 <?xml version='1.0'?> <!--*-nxml-*-->
2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
4
5 <!--
6   This file is part of systemd.
7
8   Copyright 2010 Lennart Poettering
9
10   systemd is free software; you can redistribute it and/or modify it
11   under the terms of the GNU Lesser General Public License as published by
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13   (at your option) any later version.
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18   Lesser General Public License for more details.
19
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21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
22 -->
23
24 <refentry id="systemd.unit">
25
26         <refentryinfo>
27                 <title>systemd.unit</title>
28                 <productname>systemd</productname>
29
30                 <authorgroup>
31                         <author>
32                                 <contrib>Developer</contrib>
33                                 <firstname>Lennart</firstname>
34                                 <surname>Poettering</surname>
35                                 <email>lennart@poettering.net</email>
36                         </author>
37                 </authorgroup>
38         </refentryinfo>
39
40         <refmeta>
41                 <refentrytitle>systemd.unit</refentrytitle>
42                 <manvolnum>5</manvolnum>
43         </refmeta>
44
45         <refnamediv>
46                 <refname>systemd.unit</refname>
47                 <refpurpose>Unit configuration</refpurpose>
48         </refnamediv>
49
50         <refsynopsisdiv>
51                 <para><filename>systemd.service</filename>,
52                 <filename>systemd.socket</filename>,
53                 <filename>systemd.device</filename>,
54                 <filename>systemd.mount</filename>,
55                 <filename>systemd.automount</filename>,
56                 <filename>systemd.swap</filename>,
57                 <filename>systemd.target</filename>,
58                 <filename>systemd.path</filename>,
59                 <filename>systemd.timer</filename>,
60                 <filename>systemd.snapshot</filename></para>
61         </refsynopsisdiv>
62
63         <refsect1>
64                 <title>Description</title>
65
66                 <para>A unit configuration file encodes information
67                 about a service, a socket, a device, a mount point, an
68                 automount point, a swap file or partition, a start-up
69                 target, a file system path or a timer controlled and
70                 supervised by
71                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The
72                 syntax is inspired by <ulink
73                 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
74                 Desktop Entry Specification</ulink> <filename>.desktop</filename> files, which are in turn
75                 inspired by Microsoft Windows
76                 <filename>.ini</filename> files.</para>
77
78                 <para>This man pages lists the common configuration
79                 options of all the unit types. These options need to
80                 be configured in the [Unit] resp. [Install]
81                 section of the unit files.</para>
82
83                 <para>In addition to the generic [Unit] and [Install]
84                 sections described here, each unit should have a
85                 type-specific section, e.g. [Service] for a service
86                 unit. See the respective man pages for more
87                 information.</para>
88
89                 <para>Unit files may contain additional options on top
90                 of those listed here. If systemd encounters an unknown
91                 option it will write a warning log message but
92                 continue loading the unit. If an option is prefixed
93                 with <option>X-</option> it is ignored completely by
94                 systemd. Applications may use this to include
95                 additional information in the unit files.</para>
96
97                 <para>Boolean arguments used in unit files can be
98                 written in various formats. For positive settings the
99                 strings <option>1</option>, <option>yes</option>,
100                 <option>true</option> and <option>on</option> are
101                 equivalent. For negative settings the strings
102                 <option>0</option>, <option>no</option>,
103                 <option>false</option> and <option>off</option> are
104                 equivalent.</para>
105
106                 <para>Time span values encoded in unit files can be
107                 written in various formats. A stand-alone number
108                 specifies a time in seconds. If suffixed with a time
109                 unit, the unit is honored. A concatenation of
110                 multiple values with units is supported, in which case
111                 the values are added up. Example: "50" refers to 50
112                 seconds; "2min 200ms" refers to 2 minutes plus 200
113                 milliseconds, i.e. 120200ms. The following time units
114                 are understood: s, min, h, d, w, ms, us.</para>
115
116                 <para>Empty lines and lines starting with # or ; are
117                 ignored. This may be used for commenting. Lines ending
118                 in a backslash are concatenated with the following
119                 line while reading and the backslash is replaced by a
120                 space character. This may be used to wrap long lines.</para>
121
122                 <para>If a line starts with <option>.include</option>
123                 followed by a file name, the specified file will be
124                 parsed at this point. Make sure that the file that is
125                 included has the appropriate section headers before
126                 any directives.</para>
127
128                 <para>Along with a unit file
129                 <filename>foo.service</filename> a directory
130                 <filename>foo.service.wants/</filename> may exist. All
131                 units symlinked from such a directory are implicitly
132                 added as dependencies of type
133                 <varname>Wanted=</varname> to the unit. This is useful
134                 to hook units into the start-up of other units,
135                 without having to modify their unit configuration
136                 files. For details about the semantics of
137                 <varname>Wanted=</varname> see below. The preferred
138                 way to create symlinks in the
139                 <filename>.wants/</filename> directory of a service is
140                 with the <command>enable</command> command of the
141                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
142                 tool which reads information from the [Install]
143                 section of unit files. (See below.) A similar
144                 functionality exists for <varname>Requires=</varname>
145                 type dependencies as well, the directory suffix is
146                 <filename>.requires/</filename> in this case.</para>
147
148                 <para>Note that while systemd offers a flexible
149                 dependency system between units it is recommended to
150                 use this functionality only sparsely and instead rely
151                 on techniques such as bus-based or socket-based
152                 activation which makes dependencies implicit, which
153                 both results in a simpler and more flexible
154                 system.</para>
155
156                 <para>Some unit names reflect paths existing in the
157                 file system name space. Example: a device unit
158                 <filename>dev-sda.device</filename> refers to a device
159                 with the device node <filename>/dev/sda</filename> in
160                 the file system namespace. If this applies a special
161                 way to escape the path name is used, so that the
162                 result is usable as part of a file name. Basically,
163                 given a path, "/" is replaced by "-", and all
164                 unprintable characters and the "-" are replaced by
165                 C-style "\x20" escapes. The root directory "/" is
166                 encoded as single dash, while otherwise the initial
167                 and ending "/" is removed from all paths during
168                 transformation. This escaping is reversible.</para>
169
170                 <para>Optionally, units may be instantiated from a
171                 template file at runtime. This allows creation of
172                 multiple units from a single configuration file. If
173                 systemd looks for a unit configuration file it will
174                 first search for the literal unit name in the
175                 filesystem. If that yields no success and the unit
176                 name contains an @ character, systemd will look for a
177                 unit template that shares the same name but with the
178                 instance string (i.e. the part between the @ character
179                 and the suffix) removed. Example: if a service
180                 <filename>getty@tty3.service</filename> is requested
181                 and no file by that name is found, systemd will look
182                 for <filename>getty@.service</filename> and
183                 instantiate a service from that configuration file if
184                 it is found.</para>
185
186                 <para>To refer to the instance string from
187                 within the configuration file you may use the special
188                 <literal>%i</literal> specifier in many of the
189                 configuration options. Other specifiers exist, the
190                 full list is:</para>
191
192                 <table>
193                   <title>Specifiers available in unit files</title>
194                   <tgroup cols='3' align='left' colsep='1' rowsep='1'>
195                     <colspec colname="spec" />
196                     <colspec colname="mean" />
197                     <colspec colname="detail" />
198                     <thead>
199                       <row>
200                         <entry>Specifier</entry>
201                         <entry>Meaning</entry>
202                         <entry>Details</entry>
203                       </row>
204                     </thead>
205                     <tbody>
206                       <row>
207                         <entry><literal>%n</literal></entry>
208                         <entry>Full unit name</entry>
209                         <entry></entry>
210                       </row>
211                       <row>
212                         <entry><literal>%N</literal></entry>
213                         <entry>Unescaped full unit name</entry>
214                         <entry></entry>
215                       </row>
216                       <row>
217                         <entry><literal>%p</literal></entry>
218                         <entry>Prefix name</entry>
219                         <entry>This refers to the string before the @, i.e. "getty" in the example above, where "tty3" is the instance name.</entry>
220                       </row>
221                       <row>
222                         <entry><literal>%P</literal></entry>
223                         <entry>Unescaped prefix name</entry>
224                         <entry></entry>
225                       </row>
226                       <row>
227                         <entry><literal>%i</literal></entry>
228                         <entry>Instance name</entry>
229                         <entry>This is the string between the @ character and the suffix.</entry>
230                       </row>
231                       <row>
232                         <entry><literal>%I</literal></entry>
233                         <entry>Unescaped instance name</entry>
234                         <entry></entry>
235                       </row>
236                       <row>
237                         <entry><literal>%f</literal></entry>
238                         <entry>Unescaped file name</entry>
239                         <entry>This is either the unescaped instance name (if set) with / prepended (if necessary), or the prefix name similarly prepended with /.</entry>
240                       </row>
241                       <row>
242                         <entry><literal>%c</literal></entry>
243                         <entry>Control group path of the unit</entry>
244                         <entry></entry>
245                       </row>
246                       <row>
247                         <entry><literal>%r</literal></entry>
248                         <entry>Root control group path of systemd</entry>
249                         <entry></entry>
250                       </row>
251                       <row>
252                         <entry><literal>%R</literal></entry>
253                         <entry>Parent directory of the root control group path of systemd</entry>
254                         <entry></entry>
255                       </row>
256                       <row>
257                         <entry><literal>%t</literal></entry>
258                         <entry>Runtime socket dir</entry>
259                         <entry>This is either /run (for the system manager) or $XDG_RUNTIME_DIR (for user managers).</entry>
260                       </row>
261                       <row>
262                         <entry><literal>%u</literal></entry>
263                         <entry>User name</entry>
264                         <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
265                       </row>
266                       <row>
267                         <entry><literal>%h</literal></entry>
268                         <entry>User home directory</entry>
269                         <entry>This is the home directory of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
270                       </row>
271                       <row>
272                         <entry><literal>%s</literal></entry>
273                         <entry>User shell</entry>
274                         <entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
275                       </row>
276                     </tbody>
277                   </tgroup>
278                 </table>
279
280                 <para>If a unit file is empty (i.e. has the file size
281                 0) or is symlinked to <filename>/dev/null</filename>
282                 its configuration will not be loaded and it appears
283                 with a load state of <literal>masked</literal>, and
284                 cannot be activated. Use this as an effective way to
285                 fully disable a unit, making it impossible to start it
286                 even manually.</para>
287
288                 <para>The unit file format is covered by the
289                 <ulink
290                 url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
291                 Stability Promise</ulink>.</para>
292         </refsect1>
293
294         <refsect1>
295                 <title>Options</title>
296
297                 <para>Unit file may include a [Unit] section, which
298                 carries generic information about the unit that is not
299                 dependent on the type of unit:</para>
300
301                 <variablelist>
302
303                         <varlistentry>
304                                 <term><varname>Description=</varname></term>
305                                 <listitem><para>A free-form string
306                                 describing the unit. This is intended
307                                 for use in UIs to show descriptive
308                                 information along with the unit
309                                 name.</para></listitem>
310                         </varlistentry>
311
312                         <varlistentry>
313                                 <term><varname>Documentation=</varname></term>
314                                 <listitem><para>A space separated list
315                                 of URIs referencing documentation for
316                                 this unit or its
317                                 configuration. Accepted are only URIs
318                                 of the types
319                                 <literal>http://</literal>,
320                                 <literal>https://</literal>,
321                                 <literal>file:</literal>,
322                                 <literal>info:</literal>,
323                                 <literal>man:</literal>. For more
324                                 information about the syntax of these
325                                 URIs see
326                                 <citerefentry><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem>
327                         </varlistentry>
328
329                         <varlistentry>
330                                 <term><varname>Requires=</varname></term>
331
332                                 <listitem><para>Configures requirement
333                                 dependencies on other units. If this
334                                 unit gets activated, the units listed
335                                 here will be activated as well. If one
336                                 of the other units gets deactivated or
337                                 its activation fails, this unit will
338                                 be deactivated. This option may be
339                                 specified more than once, in which
340                                 case requirement dependencies for all
341                                 listed names are created. Note that
342                                 requirement dependencies do not
343                                 influence the order in which services
344                                 are started or stopped. This has to be
345                                 configured independently with the
346                                 <varname>After=</varname> or
347                                 <varname>Before=</varname> options. If
348                                 a unit
349                                 <filename>foo.service</filename>
350                                 requires a unit
351                                 <filename>bar.service</filename> as
352                                 configured with
353                                 <varname>Requires=</varname> and no
354                                 ordering is configured with
355                                 <varname>After=</varname> or
356                                 <varname>Before=</varname>, then both
357                                 units will be started simultaneously
358                                 and without any delay between them if
359                                 <filename>foo.service</filename> is
360                                 activated. Often it is a better choice
361                                 to use <varname>Wants=</varname>
362                                 instead of
363                                 <varname>Requires=</varname> in order
364                                 to achieve a system that is more
365                                 robust when dealing with failing
366                                 services.</para>
367
368                                 <para>Note that dependencies of this
369                                 type may also be configured outside of
370                                 the unit configuration file by
371                                 adding a symlink to a
372                                 <filename>.requires/</filename> directory
373                                 accompanying the unit file. For
374                                 details see above.</para></listitem>
375                         </varlistentry>
376
377                         <varlistentry>
378                                 <term><varname>RequiresOverridable=</varname></term>
379
380                                 <listitem><para>Similar to
381                                 <varname>Requires=</varname>.
382                                 Dependencies listed in
383                                 <varname>RequiresOverridable=</varname>
384                                 which cannot be fulfilled or fail to
385                                 start are ignored if the startup was
386                                 explicitly requested by the user. If
387                                 the start-up was pulled in indirectly
388                                 by some dependency or automatic
389                                 start-up of units that is not
390                                 requested by the user this dependency
391                                 must be fulfilled and otherwise the
392                                 transaction fails. Hence, this option
393                                 may be used to configure dependencies
394                                 that are normally honored unless the
395                                 user explicitly starts up the unit, in
396                                 which case whether they failed or not
397                                 is irrelevant.</para></listitem>
398
399                         </varlistentry>
400                         <varlistentry>
401                                 <term><varname>Requisite=</varname></term>
402                                 <term><varname>RequisiteOverridable=</varname></term>
403
404                                 <listitem><para>Similar to
405                                 <varname>Requires=</varname>
406                                 resp. <varname>RequiresOverridable=</varname>. However,
407                                 if a unit listed here is not started
408                                 already it will not be started and the
409                                 transaction fails
410                                 immediately.</para></listitem>
411                         </varlistentry>
412
413                         <varlistentry>
414                                 <term><varname>Wants=</varname></term>
415
416                                 <listitem><para>A weaker version of
417                                 <varname>Requires=</varname>. A unit
418                                 listed in this option will be started
419                                 if the configuring unit is. However,
420                                 if the listed unit fails to start up
421                                 or cannot be added to the transaction
422                                 this has no impact on the validity of
423                                 the transaction as a whole. This is
424                                 the recommended way to hook start-up
425                                 of one unit to the start-up of another
426                                 unit.</para>
427
428                                 <para>Note that dependencies of this
429                                 type may also be configured outside of
430                                 the unit configuration file by
431                                 adding a symlink to a
432                                 <filename>.wants/</filename> directory
433                                 accompanying the unit file. For
434                                 details see above.</para></listitem>
435                         </varlistentry>
436
437                         <varlistentry>
438                                 <term><varname>BindsTo=</varname></term>
439
440                                 <listitem><para>Configures requirement
441                                 dependencies, very similar in style to
442                                 <varname>Requires=</varname>, however
443                                 in addition to this behaviour it also
444                                 declares that this unit is stopped
445                                 when any of the units listed suddenly
446                                 disappears. Units can suddenly,
447                                 unexpectedly disappear if a service
448                                 terminates on its own choice, a device
449                                 is unplugged or a mount point
450                                 unmounted without involvement of
451                                 systemd.</para></listitem>
452                         </varlistentry>
453
454                         <varlistentry>
455                                 <term><varname>PartOf=</varname></term>
456
457                                 <listitem><para>Configures dependencies
458                                 similar to <varname>Requires=</varname>,
459                                 but limited to stopping and restarting
460                                 of units. When systemd stops or restarts
461                                 the units listed here, the action is
462                                 propagated to this unit.
463                                 Note that this is a one way dependency -
464                                 changes to this unit do not affect the
465                                 listed units.
466                                 </para></listitem>
467                         </varlistentry>
468
469                         <varlistentry>
470                                 <term><varname>Conflicts=</varname></term>
471
472                                 <listitem><para>Configures negative
473                                 requirement dependencies. If a unit
474                                 has a
475                                 <varname>Conflicts=</varname> setting
476                                 on another unit, starting the former
477                                 will stop the latter and vice
478                                 versa. Note that this setting is
479                                 independent of and orthogonal to the
480                                 <varname>After=</varname> and
481                                 <varname>Before=</varname> ordering
482                                 dependencies.</para>
483
484                                 <para>If a unit A that conflicts with
485                                 a unit B is scheduled to be started at
486                                 the same time as B, the transaction
487                                 will either fail (in case both are
488                                 required part of the transaction) or
489                                 be modified to be fixed (in case one
490                                 or both jobs are not a required part
491                                 of the transaction). In the latter
492                                 case the job that is not the required
493                                 will be removed, or in case both are
494                                 not required the unit that conflicts
495                                 will be started and the unit that is
496                                 conflicted is
497                                 stopped.</para></listitem>
498                         </varlistentry>
499
500                         <varlistentry>
501                                 <term><varname>Before=</varname></term>
502                                 <term><varname>After=</varname></term>
503
504                                 <listitem><para>Configures ordering
505                                 dependencies between units. If a unit
506                                 <filename>foo.service</filename>
507                                 contains a setting
508                                 <option>Before=bar.service</option>
509                                 and both units are being started,
510                                 <filename>bar.service</filename>'s
511                                 start-up is delayed until
512                                 <filename>foo.service</filename> is
513                                 started up. Note that this setting is
514                                 independent of and orthogonal to the
515                                 requirement dependencies as configured
516                                 by <varname>Requires=</varname>. It is
517                                 a common pattern to include a unit
518                                 name in both the
519                                 <varname>After=</varname> and
520                                 <varname>Requires=</varname> option in
521                                 which case the unit listed will be
522                                 started before the unit that is
523                                 configured with these options. This
524                                 option may be specified more than
525                                 once, in which case ordering
526                                 dependencies for all listed names are
527                                 created. <varname>After=</varname> is
528                                 the inverse of
529                                 <varname>Before=</varname>, i.e. while
530                                 <varname>After=</varname> ensures that
531                                 the configured unit is started after
532                                 the listed unit finished starting up,
533                                 <varname>Before=</varname> ensures the
534                                 opposite, i.e.  that the configured
535                                 unit is fully started up before the
536                                 listed unit is started. Note that when
537                                 two units with an ordering dependency
538                                 between them are shut down, the
539                                 inverse of the start-up order is
540                                 applied. i.e. if a unit is configured
541                                 with <varname>After=</varname> on
542                                 another unit, the former is stopped
543                                 before the latter if both are shut
544                                 down. If one unit with an ordering
545                                 dependency on another unit is shut
546                                 down while the latter is started up,
547                                 the shut down is ordered before the
548                                 start-up regardless whether the
549                                 ordering dependency is actually of
550                                 type <varname>After=</varname> or
551                                 <varname>Before=</varname>. If two
552                                 units have no ordering dependencies
553                                 between them they are shut down
554                                 resp. started up simultaneously, and
555                                 no ordering takes
556                                 place. </para></listitem>
557                         </varlistentry>
558
559                         <varlistentry>
560                                 <term><varname>OnFailure=</varname></term>
561
562                                 <listitem><para>Lists one or more
563                                 units that are activated when this
564                                 unit enters the
565                                 '<literal>failed</literal>'
566                                 state.</para></listitem>
567                         </varlistentry>
568
569                         <varlistentry>
570                                 <term><varname>PropagatesReloadTo=</varname></term>
571                                 <term><varname>ReloadPropagatedFrom=</varname></term>
572
573                                 <listitem><para>Lists one or more
574                                 units where reload requests on the
575                                 unit will be propagated to/on the
576                                 other unit will be propagated
577                                 from. Issuing a reload request on a
578                                 unit will automatically also enqueue a
579                                 reload request on all units that the
580                                 reload request shall be propagated to
581                                 via these two
582                                 settings.</para></listitem>
583                         </varlistentry>
584
585                         <varlistentry>
586                                 <term><varname>RequiresMountsFor=</varname></term>
587
588                                 <listitem><para>Takes a space
589                                 separated list of paths. Automatically
590                                 adds dependencies of type
591                                 <varname>Requires=</varname> and
592                                 <varname>After=</varname> for all
593                                 mount units required to access the
594                                 specified path.</para></listitem>
595                         </varlistentry>
596
597                         <varlistentry>
598                                 <term><varname>OnFailureIsolate=</varname></term>
599
600                                 <listitem><para>Takes a boolean
601                                 argument. If <option>true</option> the
602                                 unit listed in
603                                 <varname>OnFailure=</varname> will be
604                                 enqueued in isolation mode, i.e. all
605                                 units that are not its dependency will
606                                 be stopped. If this is set only a
607                                 single unit may be listed in
608                                 <varname>OnFailure=</varname>. Defaults
609                                 to
610                                 <option>false</option>.</para></listitem>
611                         </varlistentry>
612
613                         <varlistentry>
614                                 <term><varname>IgnoreOnIsolate=</varname></term>
615
616                                 <listitem><para>Takes a boolean
617                                 argument. If <option>true</option>
618                                 this unit will not be stopped when
619                                 isolating another unit. Defaults to
620                                 <option>false</option>.</para></listitem>
621                         </varlistentry>
622
623                         <varlistentry>
624                                 <term><varname>IgnoreOnSnapshot=</varname></term>
625
626                                 <listitem><para>Takes a boolean
627                                 argument. If <option>true</option>
628                                 this unit will not be included in
629                                 snapshots. Defaults to
630                                 <option>true</option> for device and
631                                 snapshot units, <option>false</option>
632                                 for the others.</para></listitem>
633                         </varlistentry>
634
635                         <varlistentry>
636                                 <term><varname>StopWhenUnneeded=</varname></term>
637
638                                 <listitem><para>Takes a boolean
639                                 argument. If <option>true</option>
640                                 this unit will be stopped when it is
641                                 no longer used. Note that in order to
642                                 minimize the work to be executed,
643                                 systemd will not stop units by default
644                                 unless they are conflicting with other
645                                 units, or the user explicitly
646                                 requested their shut down. If this
647                                 option is set, a unit will be
648                                 automatically cleaned up if no other
649                                 active unit requires it. Defaults to
650                                 <option>false</option>.</para></listitem>
651                         </varlistentry>
652
653                         <varlistentry>
654                                 <term><varname>RefuseManualStart=</varname></term>
655                                 <term><varname>RefuseManualStop=</varname></term>
656
657                                 <listitem><para>Takes a boolean
658                                 argument. If <option>true</option>
659                                 this unit can only be activated
660                                 (resp. deactivated) indirectly. In
661                                 this case explicit start-up
662                                 (resp. termination) requested by the
663                                 user is denied, however if it is
664                                 started (resp. stopped) as a
665                                 dependency of another unit, start-up
666                                 (resp. termination) will succeed. This
667                                 is mostly a safety feature to ensure
668                                 that the user does not accidentally
669                                 activate units that are not intended
670                                 to be activated explicitly, and not
671                                 accidentally deactivate units that are
672                                 not intended to be deactivated.
673                                 These options default to
674                                 <option>false</option>.</para></listitem>
675                         </varlistentry>
676
677                         <varlistentry>
678                                 <term><varname>AllowIsolate=</varname></term>
679
680                                 <listitem><para>Takes a boolean
681                                 argument. If <option>true</option>
682                                 this unit may be used with the
683                                 <command>systemctl isolate</command>
684                                 command. Otherwise this will be
685                                 refused. It probably is a good idea to
686                                 leave this disabled except for target
687                                 units that shall be used similar to
688                                 runlevels in SysV init systems, just
689                                 as a precaution to avoid unusable
690                                 system states. This option defaults to
691                                 <option>false</option>.</para></listitem>
692                         </varlistentry>
693
694                         <varlistentry>
695                                 <term><varname>DefaultDependencies=</varname></term>
696
697                                 <listitem><para>Takes a boolean
698                                 argument. If <option>true</option>
699                                 (the default), a few default
700                                 dependencies will implicitly be
701                                 created for the unit. The actual
702                                 dependencies created depend on the
703                                 unit type. For example, for service
704                                 units, these dependencies ensure that
705                                 the service is started only after
706                                 basic system initialization is
707                                 completed and is properly terminated on
708                                 system shutdown. See the respective
709                                 man pages for details. Generally, only
710                                 services involved with early boot or
711                                 late shutdown should set this option
712                                 to <option>false</option>. It is
713                                 highly recommended to leave this
714                                 option enabled for the majority of
715                                 common units. If set to
716                                 <option>false</option> this option
717                                 does not disable all implicit
718                                 dependencies, just non-essential
719                                 ones.</para></listitem>
720                         </varlistentry>
721
722                         <varlistentry>
723                                 <term><varname>JobTimeoutSec=</varname></term>
724
725                                 <listitem><para>When clients are
726                                 waiting for a job of this unit to
727                                 complete, time out after the specified
728                                 time. If this time limit is reached
729                                 the job will be cancelled, the unit
730                                 however will not change state or even
731                                 enter the '<literal>failed</literal>'
732                                 mode. This value defaults to 0 (job
733                                 timeouts disabled), except for device
734                                 units. NB: this timeout is independent
735                                 from any unit-specific timeout (for
736                                 example, the timeout set with
737                                 <varname>Timeout=</varname> in service
738                                 units) as the job timeout has no
739                                 effect on the unit itself, only on the
740                                 job that might be pending for it. Or
741                                 in other words: unit-specific timeouts
742                                 are useful to abort unit state
743                                 changes, and revert them. The job
744                                 timeout set with this option however
745                                 is useful to abort only the job
746                                 waiting for the unit state to
747                                 change.</para></listitem>
748                         </varlistentry>
749
750                         <varlistentry>
751                                 <term><varname>ConditionPathExists=</varname></term>
752                                 <term><varname>ConditionPathExistsGlob=</varname></term>
753                                 <term><varname>ConditionPathIsDirectory=</varname></term>
754                                 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
755                                 <term><varname>ConditionPathIsMountPoint=</varname></term>
756                                 <term><varname>ConditionPathIsReadWrite=</varname></term>
757                                 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
758                                 <term><varname>ConditionFileIsExecutable=</varname></term>
759                                 <term><varname>ConditionKernelCommandLine=</varname></term>
760                                 <term><varname>ConditionVirtualization=</varname></term>
761                                 <term><varname>ConditionSecurity=</varname></term>
762                                 <term><varname>ConditionCapability=</varname></term>
763                                 <term><varname>ConditionNull=</varname></term>
764
765                                 <listitem><para>Before starting a unit
766                                 verify that the specified condition is
767                                 true. With
768                                 <varname>ConditionPathExists=</varname>
769                                 a file existence condition can be
770                                 checked before a unit is started. If
771                                 the specified absolute path name does
772                                 not exist, startup of a unit will not
773                                 actually happen, however the unit is
774                                 still useful for ordering purposes in
775                                 this case. The condition is checked at
776                                 the time the queued start job is to be
777                                 executed. If the absolute path name
778                                 passed to
779                                 <varname>ConditionPathExists=</varname>
780                                 is prefixed with an exclamation mark
781                                 (!), the test is negated, and the unit
782                                 is only started if the path does not
783                                 exist.
784                                 <varname>ConditionPathExistsGlob=</varname>
785                                 works in a similar way, but checks for
786                                 the existence of at least one file or
787                                 directory matching the specified
788                                 globbing
789                                 pattern. <varname>ConditionPathIsDirectory=</varname>
790                                 is similar to
791                                 <varname>ConditionPathExists=</varname>
792                                 but verifies whether a certain path
793                                 exists and is a
794                                 directory. <varname>ConditionPathIsSymbolicLink=</varname>
795                                 is similar to
796                                 <varname>ConditionPathExists=</varname>
797                                 but verifies whether a certain path
798                                 exists and is a symbolic
799                                 link. <varname>ConditionPathIsMountPoint=</varname>
800                                 is similar to
801                                 <varname>ConditionPathExists=</varname>
802                                 but verifies whether a certain path
803                                 exists and is a mount
804                                 point. <varname>ConditionPathIsReadWrite=</varname>
805                                 is similar to
806                                 <varname>ConditionPathExists=</varname>
807                                 but verifies whether the underlying
808                                 file system is read and writable
809                                 (i.e. not mounted
810                                 read-only). <varname>ConditionFileIsExecutable=</varname>
811                                 is similar to
812                                 <varname>ConditionPathExists=</varname>
813                                 but verifies whether a certain path
814                                 exists, is a regular file and marked
815                                 executable.
816                                 <varname>ConditionDirectoryNotEmpty=</varname>
817                                 is similar to
818                                 <varname>ConditionPathExists=</varname>
819                                 but verifies whether a certain path
820                                 exists and is a non-empty
821                                 directory. Similarly
822                                 <varname>ConditionKernelCommandLine=</varname>
823                                 may be used to check whether a
824                                 specific kernel command line option is
825                                 set (or if prefixed with the
826                                 exclamation mark unset). The argument
827                                 must either be a single word, or an
828                                 assignment (i.e. two words, separated
829                                 by the equality sign). In the former
830                                 case the kernel command line is
831                                 searched for the word appearing as is,
832                                 or as left hand side of an
833                                 assignment. In the latter case the
834                                 exact assignment is looked for with
835                                 right and left hand side
836                                 matching. <varname>ConditionVirtualization=</varname>
837                                 may be used to check whether the
838                                 system is executed in a virtualized
839                                 environment and optionally test
840                                 whether it is a specific
841                                 implementation. Takes either boolean
842                                 value to check if being executed in
843                                 any virtualized environment, or one of
844                                 <varname>vm</varname> and
845                                 <varname>container</varname> to test
846                                 against a specific type of
847                                 virtualization solution, or one of
848                                 <varname>qemu</varname>,
849                                 <varname>kvm</varname>,
850                                 <varname>vmware</varname>,
851                                 <varname>microsoft</varname>,
852                                 <varname>oracle</varname>,
853                                 <varname>xen</varname>,
854                                 <varname>bochs</varname>,
855                                 <varname>chroot</varname>,
856                                 <varname>openvz</varname>,
857                                 <varname>lxc</varname>,
858                                 <varname>lxc-libvirt</varname>,
859                                 <varname>systemd-nspawn</varname> to
860                                 test against a specific
861                                 implementation. If multiple
862                                 virtualization technologies are nested
863                                 only the innermost is considered. The
864                                 test may be negated by prepending an
865                                 exclamation mark.
866                                 <varname>ConditionSecurity=</varname>
867                                 may be used to check whether the given
868                                 security module is enabled on the
869                                 system.  Currently the only recognized
870                                 value is <varname>selinux</varname>.
871                                 The test may be negated by prepending
872                                 an exclamation
873                                 mark. <varname>ConditionCapability=</varname>
874                                 may be used to check whether the given
875                                 capability exists in the capability
876                                 bounding set of the service manager
877                                 (i.e. this does not check whether
878                                 capability is actually available in
879                                 the permitted or effective sets, see
880                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
881                                 for details). Pass a capability name
882                                 such as <literal>CAP_MKNOD</literal>,
883                                 possibly prefixed with an exclamation
884                                 mark to negate the check. Finally,
885                                 <varname>ConditionNull=</varname> may
886                                 be used to add a constant condition
887                                 check value to the unit. It takes a
888                                 boolean argument. If set to
889                                 <varname>false</varname> the condition
890                                 will always fail, otherwise
891                                 succeed. If multiple conditions are
892                                 specified the unit will be executed if
893                                 all of them apply (i.e. a logical AND
894                                 is applied). Condition checks can be
895                                 prefixed with a pipe symbol (|) in
896                                 which case a condition becomes a
897                                 triggering condition. If at least one
898                                 triggering condition is defined for a
899                                 unit then the unit will be executed if
900                                 at least one of the triggering
901                                 conditions apply and all of the
902                                 non-triggering conditions. If you
903                                 prefix an argument with the pipe
904                                 symbol and an exclamation mark the
905                                 pipe symbol must be passed first, the
906                                 exclamation second. Except for
907                                 <varname>ConditionPathIsSymbolicLink=</varname>,
908                                 all path checks follow
909                                 symlinks.</para></listitem>
910                         </varlistentry>
911
912                         <varlistentry>
913                                 <term><varname>SourcePath=</varname></term>
914                                 <listitem><para>A path to a
915                                 configuration file this unit has been
916                                 generated from. This is primarily
917                                 useful for implementation of generator
918                                 tools that convert configuration from
919                                 an external configuration file format
920                                 into native unit files. Thus
921                                 functionality should not be used in
922                                 normal units.</para></listitem>
923                         </varlistentry>
924                 </variablelist>
925
926                 <para>Unit file may include a [Install] section, which
927                 carries installation information for the unit. This
928                 section is not interpreted by
929                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
930                 during runtime. It is used exclusively by the
931                 <command>enable</command> and
932                 <command>disable</command> commands of the
933                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
934                 tool during installation of a unit:</para>
935
936                 <variablelist>
937                         <varlistentry>
938                                 <term><varname>Alias=</varname></term>
939
940                                 <listitem><para>Additional names this
941                                 unit shall be installed under. The
942                                 names listed here must have the same
943                                 suffix (i.e. type) as the unit file
944                                 name. This option may be specified
945                                 more than once, in which case all
946                                 listed names are used. At installation
947                                 time,
948                                 <command>systemctl enable</command>
949                                 will create symlinks from these names
950                                 to the unit file name.</para></listitem>
951                         </varlistentry>
952
953                         <varlistentry>
954                                 <term><varname>WantedBy=</varname></term>
955                                 <term><varname>RequiredBy=</varname></term>
956
957                                 <listitem><para>Installs a symlink in
958                                 the <filename>.wants/</filename>
959                                 resp. <filename>.requires/</filename>
960                                 subdirectory for a unit. This has the
961                                 effect that when the listed unit name
962                                 is activated the unit listing it is
963                                 activated
964                                 too. <command>WantedBy=foo.service</command>
965                                 in a service
966                                 <filename>bar.service</filename> is
967                                 mostly equivalent to
968                                 <command>Alias=foo.service.wants/bar.service</command>
969                                 in the same file.</para></listitem>
970                         </varlistentry>
971
972                         <varlistentry>
973                                 <term><varname>Also=</varname></term>
974
975                                 <listitem><para>Additional units to
976                                 install when this unit is
977                                 installed. If the user requests
978                                 installation of a unit with this
979                                 option configured,
980                                 <command>systemctl enable</command>
981                                 will automatically install units
982                                 listed in this option as
983                                 well.</para></listitem>
984                         </varlistentry>
985                 </variablelist>
986
987         </refsect1>
988
989         <refsect1>
990                 <title>See Also</title>
991                 <para>
992                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
993                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
994                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
995                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
996                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
997                         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
998                         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
999                         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1000                         <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1001                         <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1002                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1003                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1004                         <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1005                         <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1006                 </para>
1007         </refsect1>
1008
1009 </refentry>