systemd.unit.xml 56.1 KB
Newer Older
1
2
3
4
5
6
7
8
9
10
<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<!--
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
11
12
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
13
14
15
16
17
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18
  Lesser General Public License for more details.
19

20
  You should have received a copy of the GNU Lesser General Public License
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->

<refentry id="systemd.unit">

        <refentryinfo>
                <title>systemd.unit</title>
                <productname>systemd</productname>

                <authorgroup>
                        <author>
                                <contrib>Developer</contrib>
                                <firstname>Lennart</firstname>
                                <surname>Poettering</surname>
                                <email>lennart@poettering.net</email>
                        </author>
                </authorgroup>
        </refentryinfo>

        <refmeta>
                <refentrytitle>systemd.unit</refentrytitle>
                <manvolnum>5</manvolnum>
        </refmeta>

        <refnamediv>
                <refname>systemd.unit</refname>
47
                <refpurpose>Unit configuration</refpurpose>
48
49
50
        </refnamediv>

        <refsynopsisdiv>
51
52
53
54
55
56
57
58
                <para><filename>systemd.service</filename>,
                <filename>systemd.socket</filename>,
                <filename>systemd.device</filename>,
                <filename>systemd.mount</filename>,
                <filename>systemd.automount</filename>,
                <filename>systemd.swap</filename>,
                <filename>systemd.target</filename>,
                <filename>systemd.path</filename>,
59
60
                <filename>systemd.timer</filename>,
                <filename>systemd.snapshot</filename></para>
61
62
63
64
65
66
        </refsynopsisdiv>

        <refsect1>
                <title>Description</title>

                <para>A unit configuration file encodes information
67
                about a service, a socket, a device, a mount point, an
Kay Sievers's avatar
Kay Sievers committed
68
                automount point, a swap file or partition, a start-up
69
                target, a file system path or a timer controlled and
70
71
72
73
                supervised by
                <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The
                syntax is inspired by <ulink
                url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
Kay Sievers's avatar
Kay Sievers committed
74
                Desktop Entry Specification</ulink> <filename>.desktop</filename> files, which are in turn
75
76
                inspired by Microsoft Windows
                <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
86
87
88
89
90
91
92
93
94
95
96
97
                type-specific section, e.g. [Service] for a service
                unit. See the respective man pages for more
                information.</para>

                <para>Unit files may contain additional options on top
                of those listed here. If systemd encounters an unknown
                option it will write a warning log message but
                continue loading the unit. If an option is prefixed
                with <option>X-</option> it is ignored completely by
                systemd. Applications may use this to include
                additional information in the unit files.</para>

                <para>Boolean arguments used in unit files can be
Lennart Poettering's avatar
Lennart Poettering committed
98
                written in various formats. For positive settings the
99
100
101
102
103
104
105
                strings <option>1</option>, <option>yes</option>,
                <option>true</option> and <option>on</option> are
                equivalent. For negative settings the strings
                <option>0</option>, <option>no</option>,
                <option>false</option> and <option>off</option> are
                equivalent.</para>

106
107
108
                <para>Time span values encoded in unit files can be
                written in various formats. A stand-alone number
                specifies a time in seconds. If suffixed with a time
Kay Sievers's avatar
Kay Sievers committed
109
                unit, the unit is honored. A concatenation of
110
                multiple values with units is supported, in which case
111
112
113
114
115
                the values are added up. Example: "50" refers to 50
                seconds; "2min 200ms" refers to 2 minutes plus 200
                milliseconds, i.e. 120200ms. The following time units
                are understood: s, min, h, d, w, ms, us.</para>

116
                <para>Empty lines and lines starting with # or ; are
117
118
119
120
                ignored. This may be used for commenting. Lines ending
                in a backslash are concatenated with the following
                line while reading and the backslash is replaced by a
                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
Michael Biebl's avatar
Michael Biebl committed
125
                included has the appropriate section headers before
126
                any directives.</para>
127
128
129
130
131
132
133
134
135
136
137
138
139

                <para>Along with a unit file
                <filename>foo.service</filename> a directory
                <filename>foo.service.wants/</filename> may exist. All
                units symlinked from such a directory are implicitly
                added as dependencies of type
                <varname>Wanted=</varname> to the unit. This is useful
                to hook units into the start-up of other units,
                without having to modify their unit configuration
                files. For details about the semantics of
                <varname>Wanted=</varname> see below. The preferred
                way to create symlinks in the
                <filename>.wants/</filename> directory of a service is
140
141
                with the <command>enable</command> command of the
                <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
142
                tool which reads information from the [Install]
143
144
145
146
                section of unit files. (See below.) A similar
                functionality exists for <varname>Requires=</varname>
                type dependencies as well, the directory suffix is
                <filename>.requires/</filename> in this case.</para>
147
148
149
150
151
152
153
154

                <para>Note that while systemd offers a flexible
                dependency system between units it is recommended to
                use this functionality only sparsely and instead rely
                on techniques such as bus-based or socket-based
                activation which makes dependencies implicit, which
                both results in a simpler and more flexible
                system.</para>
155
156
157
158
159
160

                <para>Some unit names reflect paths existing in the
                file system name space. Example: a device unit
                <filename>dev-sda.device</filename> refers to a device
                with the device node <filename>/dev/sda</filename> in
                the file system namespace. If this applies a special
Lennart Poettering's avatar
Lennart Poettering committed
161
162
163
164
165
166
167
168
                way to escape the path name is used, so that the
                result is usable as part of a file name. Basically,
                given a path, "/" is replaced by "-", and all
                unprintable characters and the "-" are replaced by
                C-style "\x20" escapes. The root directory "/" is
                encoded as single dash, while otherwise the initial
                and ending "/" is removed from all paths during
                transformation. This escaping is reversible.</para>
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183

                <para>Optionally, units may be instantiated from a
                template file at runtime. This allows creation of
                multiple units from a single configuration file. If
                systemd looks for a unit configuration file it will
                first search for the literal unit name in the
                filesystem. If that yields no success and the unit
                name contains an @ character, systemd will look for a
                unit template that shares the same name but with the
                instance string (i.e. the part between the @ character
                and the suffix) removed. Example: if a service
                <filename>getty@tty3.service</filename> is requested
                and no file by that name is found, systemd will look
                for <filename>getty@.service</filename> and
                instantiate a service from that configuration file if
184
185
186
                it is found.</para>

                <para>To refer to the instance string from
187
188
                within the configuration file you may use the special
                <literal>%i</literal> specifier in many of the
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
                configuration options. Other specifiers exist, the
                full list is:</para>

                <table>
                  <title>Specifiers available in unit files</title>
                  <tgroup cols='3' align='left' colsep='1' rowsep='1'>
                    <colspec colname="spec" />
                    <colspec colname="mean" />
                    <colspec colname="detail" />
                    <thead>
                      <row>
                        <entry>Specifier</entry>
                        <entry>Meaning</entry>
                        <entry>Details</entry>
                      </row>
                    </thead>
                    <tbody>
                      <row>
                        <entry><literal>%n</literal></entry>
                        <entry>Full unit name</entry>
                        <entry></entry>
                      </row>
                      <row>
                        <entry><literal>%N</literal></entry>
                        <entry>Unescaped full unit name</entry>
                        <entry></entry>
                      </row>
                      <row>
                        <entry><literal>%p</literal></entry>
                        <entry>Prefix name</entry>
                        <entry>This refers to the string before the @, i.e. "getty" in the example above, where "tty3" is the instance name.</entry>
                      </row>
                      <row>
                        <entry><literal>%P</literal></entry>
                        <entry>Unescaped prefix name</entry>
                        <entry></entry>
                      </row>
                      <row>
                        <entry><literal>%i</literal></entry>
                        <entry>Instance name</entry>
                        <entry>This is the string between the @ character and the suffix.</entry>
                      </row>
                      <row>
                        <entry><literal>%I</literal></entry>
                        <entry>Unescaped instance name</entry>
                        <entry></entry>
                      </row>
                      <row>
                        <entry><literal>%f</literal></entry>
                        <entry>Unescaped file name</entry>
                        <entry>This is either the unescaped instance name (if set) with / prepended (if necessary), or the prefix name similarly prepended with /.</entry>
                      </row>
                      <row>
                        <entry><literal>%c</literal></entry>
                        <entry>Control group path of the unit</entry>
                        <entry></entry>
                      </row>
                      <row>
                        <entry><literal>%r</literal></entry>
                        <entry>Root control group path of systemd</entry>
                        <entry></entry>
                      </row>
                      <row>
                        <entry><literal>%R</literal></entry>
                        <entry>Parent directory of the root control group path of systemd</entry>
                        <entry></entry>
                      </row>
                      <row>
                        <entry><literal>%t</literal></entry>
                        <entry>Runtime socket dir</entry>
                        <entry>This is either /run (for the system manager) or $XDG_RUNTIME_DIR (for user managers).</entry>
                      </row>
261
262
263
264
265
266
267
268
269
270
                      <row>
                        <entry><literal>%u</literal></entry>
                        <entry>User name</entry>
                        <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
                      </row>
                      <row>
                        <entry><literal>%h</literal></entry>
                        <entry>User home directory</entry>
                        <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>
                      </row>
271
272
273
274
275
                      <row>
                        <entry><literal>%s</literal></entry>
                        <entry>User shell</entry>
                        <entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
                      </row>
276
277
278
                    </tbody>
                  </tgroup>
                </table>
279

280
281
282
283
284
285
286
287
                <para>If a unit file is empty (i.e. has the file size
                0) or is symlinked to <filename>/dev/null</filename>
                its configuration will not be loaded and it appears
                with a load state of <literal>masked</literal>, and
                cannot be activated. Use this as an effective way to
                fully disable a unit, making it impossible to start it
                even manually.</para>

288
289
290
291
                <para>The unit file format is covered by the
                <ulink
                url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
                Stability Promise</ulink>.</para>
292
293
294
295
296
        </refsect1>

        <refsect1>
                <title>Options</title>

297
298
299
300
                <para>Unit file may include a [Unit] section, which
                carries generic information about the unit that is not
                dependent on the type of unit:</para>

301
                <variablelist>
302
303
304
305

                        <varlistentry>
                                <term><varname>Description=</varname></term>
                                <listitem><para>A free-form string
306
307
308
309
                                describing the unit. This is intended
                                for use in UIs to show descriptive
                                information along with the unit
                                name.</para></listitem>
310
311
                        </varlistentry>

312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
                        <varlistentry>
                                <term><varname>Documentation=</varname></term>
                                <listitem><para>A space separated list
                                of URIs referencing documentation for
                                this unit or its
                                configuration. Accepted are only URIs
                                of the types
                                <literal>http://</literal>,
                                <literal>https://</literal>,
                                <literal>file:</literal>,
                                <literal>info:</literal>,
                                <literal>man:</literal>. For more
                                information about the syntax of these
                                URIs see
                                <citerefentry><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem>
                        </varlistentry>

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
336
337
338
339
340
                                here will be activated as well. If one
                                of the other units gets deactivated or
                                its activation fails, this unit will
                                be deactivated. This option may be
                                specified more than once, in which
                                case requirement dependencies for all
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
                                listed names are created. Note that
                                requirement dependencies do not
                                influence the order in which services
                                are started or stopped. This has to be
                                configured independently with the
                                <varname>After=</varname> or
                                <varname>Before=</varname> options. If
                                a unit
                                <filename>foo.service</filename>
                                requires a unit
                                <filename>bar.service</filename> as
                                configured with
                                <varname>Requires=</varname> and no
                                ordering is configured with
                                <varname>After=</varname> or
                                <varname>Before=</varname>, then both
                                units will be started simultaneously
                                and without any delay between them if
                                <filename>foo.service</filename> is
                                activated. Often it is a better choice
                                to use <varname>Wants=</varname>
                                instead of
                                <varname>Requires=</varname> in order
                                to achieve a system that is more
                                robust when dealing with failing
                                services.</para></listitem>
367
                        </varlistentry>
368
369
370
371
372
373
374
375
376

                        <varlistentry>
                                <term><varname>RequiresOverridable=</varname></term>

                                <listitem><para>Similar to
                                <varname>Requires=</varname>.
                                Dependencies listed in
                                <varname>RequiresOverridable=</varname>
                                which cannot be fulfilled or fail to
377
                                start are ignored if the startup was
378
379
380
381
382
383
384
385
                                explicitly requested by the user. If
                                the start-up was pulled in indirectly
                                by some dependency or automatic
                                start-up of units that is not
                                requested by the user this dependency
                                must be fulfilled and otherwise the
                                transaction fails. Hence, this option
                                may be used to configure dependencies
Kay Sievers's avatar
Kay Sievers committed
386
                                that are normally honored unless the
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
                                user explicitly starts up the unit, in
                                which case whether they failed or not
                                is irrelevant.</para></listitem>

                        </varlistentry>
                        <varlistentry>
                                <term><varname>Requisite=</varname></term>
                                <term><varname>RequisiteOverridable=</varname></term>

                                <listitem><para>Similar to
                                <varname>Requires=</varname>
                                resp. <varname>RequiresOverridable=</varname>. However,
                                if a unit listed here is not started
                                already it will not be started and the
                                transaction fails
                                immediately.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>Wants=</varname></term>

                                <listitem><para>A weaker version of
                                <varname>Requires=</varname>. A unit
                                listed in this option will be started
                                if the configuring unit is. However,
412
                                if the listed unit fails to start up
413
414
415
416
417
418
419
420
421
422
423
424
425
426
                                or cannot be added to the transaction
                                this has no impact on the validity of
                                the transaction as a whole. This is
                                the recommended way to hook start-up
                                of one unit to the start-up of another
                                unit. Note that dependencies of this
                                type may also be configured outside of
                                the unit configuration file by
                                adding a symlink to a
                                <filename>.wants/</filename> directory
                                accompanying the unit file. For
                                details see above.</para></listitem>
                        </varlistentry>

427
                        <varlistentry>
428
                                <term><varname>BindsTo=</varname></term>
429
430
431
432
433
434
435
436
437
438
439

                                <listitem><para>Configures requirement
                                dependencies, very similar in style to
                                <varname>Requires=</varname>, however
                                in addition to this behaviour it also
                                declares that this unit is stopped
                                when any of the units listed suddenly
                                disappears. Units can suddenly,
                                unexpectedly disappear if a service
                                terminates on its own choice, a device
                                is unplugged or a mount point
440
                                unmounted without involvement of
441
442
443
                                systemd.</para></listitem>
                        </varlistentry>

444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
                        <varlistentry>
                                <term><varname>PartOf=</varname></term>

                                 <listitem><para>Configures dependency
                                 on other unit. When systemd stops or
                                 restarts unit listed here, stop or
                                 restart is propagated to dependent
                                 units. Note that this is one way
                                 dependency and changes to dependent
                                 units does not affect listed unit. If
                                 something else is desired, please
                                 use some other type of dependency.
                                 </para></listitem>
                        </varlistentry>

459
460
461
462
463
                        <varlistentry>
                                <term><varname>Conflicts=</varname></term>

                                <listitem><para>Configures negative
                                requirement dependencies. If a unit
464
                                has a
465
                                <varname>Conflicts=</varname> setting
466
                                on another unit, starting the former
467
468
469
470
471
                                will stop the latter and vice
                                versa. Note that this setting is
                                independent of and orthogonal to the
                                <varname>After=</varname> and
                                <varname>Before=</varname> ordering
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
                                dependencies.</para>

                                <para>If a unit A that conflicts with
                                a unit B is scheduled to be started at
                                the same time as B, the transaction
                                will either fail (in case both are
                                required part of the transaction) or
                                be modified to be fixed (in case one
                                or both jobs are not a required part
                                of the transaction). In the latter
                                case the job that is not the required
                                will be removed, or in case both are
                                not required the unit that conflicts
                                will be started and the unit that is
                                conflicted is
                                stopped.</para></listitem>
488
489
490
491
492
493
494
495
496
497
498
                        </varlistentry>

                        <varlistentry>
                                <term><varname>Before=</varname></term>
                                <term><varname>After=</varname></term>

                                <listitem><para>Configures ordering
                                dependencies between units. If a unit
                                <filename>foo.service</filename>
                                contains a setting
                                <option>Before=bar.service</option>
499
                                and both units are being started,
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
                                <filename>bar.service</filename>'s
                                start-up is delayed until
                                <filename>foo.service</filename> is
                                started up. Note that this setting is
                                independent of and orthogonal to the
                                requirement dependencies as configured
                                by <varname>Requires=</varname>. It is
                                a common pattern to include a unit
                                name in both the
                                <varname>After=</varname> and
                                <varname>Requires=</varname> option in
                                which case the unit listed will be
                                started before the unit that is
                                configured with these options. This
                                option may be specified more than
                                once, in which case ordering
                                dependencies for all listed names are
                                created. <varname>After=</varname> is
                                the inverse of
                                <varname>Before=</varname>, i.e. while
                                <varname>After=</varname> ensures that
                                the configured unit is started after
                                the listed unit finished starting up,
                                <varname>Before=</varname> ensures the
                                opposite, i.e.  that the configured
                                unit is fully started up before the
                                listed unit is started. Note that when
                                two units with an ordering dependency
                                between them are shut down, the
529
                                inverse of the start-up order is
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
                                applied. i.e. if a unit is configured
                                with <varname>After=</varname> on
                                another unit, the former is stopped
                                before the latter if both are shut
                                down. If one unit with an ordering
                                dependency on another unit is shut
                                down while the latter is started up,
                                the shut down is ordered before the
                                start-up regardless whether the
                                ordering dependency is actually of
                                type <varname>After=</varname> or
                                <varname>Before=</varname>. If two
                                units have no ordering dependencies
                                between them they are shut down
                                resp. started up simultaneously, and
                                no ordering takes
                                place. </para></listitem>
                        </varlistentry>

549
550
551
552
553
                        <varlistentry>
                                <term><varname>OnFailure=</varname></term>

                                <listitem><para>Lists one or more
                                units that are activated when this
554
555
556
                                unit enters the
                                '<literal>failed</literal>'
                                state.</para></listitem>
557
558
                        </varlistentry>

559
                        <varlistentry>
560
561
                                <term><varname>PropagatesReloadTo=</varname></term>
                                <term><varname>ReloadPropagatedFrom=</varname></term>
562
563
564
565
566
567
568
569
570
571
572
573
574

                                <listitem><para>Lists one or more
                                units where reload requests on the
                                unit will be propagated to/on the
                                other unit will be propagated
                                from. Issuing a reload request on a
                                unit will automatically also enqueue a
                                reload request on all units that the
                                reload request shall be propagated to
                                via these two
                                settings.</para></listitem>
                        </varlistentry>

575
576
577
578
579
580
581
582
583
584
585
586
                        <varlistentry>
                                <term><varname>RequiresMountsFor=</varname></term>

                                <listitem><para>Takes a space
                                separated list of paths. Automatically
                                adds dependencies of type
                                <varname>Requires=</varname> and
                                <varname>After=</varname> for all
                                mount units required to access the
                                specified path.</para></listitem>
                        </varlistentry>

587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
                        <varlistentry>
                                <term><varname>OnFailureIsolate=</varname></term>

                                <listitem><para>Takes a boolean
                                argument. If <option>true</option> the
                                unit listed in
                                <varname>OnFailure=</varname> will be
                                enqueued in isolation mode, i.e. all
                                units that are not its dependency will
                                be stopped. If this is set only a
                                single unit may be listed in
                                <varname>OnFailure=</varname>. Defaults
                                to
                                <option>false</option>.</para></listitem>
                        </varlistentry>

603
604
605
606
607
608
609
610
611
612
                        <varlistentry>
                                <term><varname>IgnoreOnIsolate=</varname></term>

                                <listitem><para>Takes a boolean
                                argument. If <option>true</option>
                                this unit will not be stopped when
                                isolating another unit. Defaults to
                                <option>false</option>.</para></listitem>
                        </varlistentry>

613
614
615
616
617
618
619
                        <varlistentry>
                                <term><varname>IgnoreOnSnapshot=</varname></term>

                                <listitem><para>Takes a boolean
                                argument. If <option>true</option>
                                this unit will not be included in
                                snapshots. Defaults to
620
621
                                <option>true</option> for device and
                                snapshot units, <option>false</option>
622
623
624
                                for the others.</para></listitem>
                        </varlistentry>

625
626
627
628
629
630
631
                        <varlistentry>
                                <term><varname>StopWhenUnneeded=</varname></term>

                                <listitem><para>Takes a boolean
                                argument. If <option>true</option>
                                this unit will be stopped when it is
                                no longer used. Note that in order to
632
633
                                minimize the work to be executed,
                                systemd will not stop units by default
634
635
636
                                unless they are conflicting with other
                                units, or the user explicitly
                                requested their shut down. If this
637
                                option is set, a unit will be
638
639
640
641
642
643
                                automatically cleaned up if no other
                                active unit requires it. Defaults to
                                <option>false</option>.</para></listitem>
                        </varlistentry>

                        <varlistentry>
644
645
                                <term><varname>RefuseManualStart=</varname></term>
                                <term><varname>RefuseManualStop=</varname></term>
646
647
648

                                <listitem><para>Takes a boolean
                                argument. If <option>true</option>
649
                                this unit can only be activated
650
651
652
653
654
                                (resp. deactivated) indirectly. In
                                this case explicit start-up
                                (resp. termination) requested by the
                                user is denied, however if it is
                                started (resp. stopped) as a
655
                                dependency of another unit, start-up
656
657
658
659
660
661
662
663
                                (resp. termination) will succeed. This
                                is mostly a safety feature to ensure
                                that the user does not accidentally
                                activate units that are not intended
                                to be activated explicitly, and not
                                accidentally deactivate units that are
                                not intended to be deactivated.
                                These options default to
664
665
666
                                <option>false</option>.</para></listitem>
                        </varlistentry>

667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
                        <varlistentry>
                                <term><varname>AllowIsolate=</varname></term>

                                <listitem><para>Takes a boolean
                                argument. If <option>true</option>
                                this unit may be used with the
                                <command>systemctl isolate</command>
                                command. Otherwise this will be
                                refused. It probably is a good idea to
                                leave this disabled except for target
                                units that shall be used similar to
                                runlevels in SysV init systems, just
                                as a precaution to avoid unusable
                                system states. This option defaults to
                                <option>false</option>.</para></listitem>
                        </varlistentry>

684
685
686
687
688
689
690
691
692
693
694
695
696
                        <varlistentry>
                                <term><varname>DefaultDependencies=</varname></term>

                                <listitem><para>Takes a boolean
                                argument. If <option>true</option>
                                (the default), a few default
                                dependencies will implicitly be
                                created for the unit. The actual
                                dependencies created depend on the
                                unit type. For example, for service
                                units, these dependencies ensure that
                                the service is started only after
                                basic system initialization is
697
                                completed and is properly terminated on
698
699
700
701
702
703
704
705
706
707
708
709
710
711
                                system shutdown. See the respective
                                man pages for details. Generally, only
                                services involved with early boot or
                                late shutdown should set this option
                                to <option>false</option>. It is
                                highly recommended to leave this
                                option enabled for the majority of
                                common units. If set to
                                <option>false</option> this option
                                does not disable all implicit
                                dependencies, just non-essential
                                ones.</para></listitem>
                        </varlistentry>

712
713
714
715
716
717
718
719
720
                        <varlistentry>
                                <term><varname>JobTimeoutSec=</varname></term>

                                <listitem><para>When clients are
                                waiting for a job of this unit to
                                complete, time out after the specified
                                time. If this time limit is reached
                                the job will be cancelled, the unit
                                however will not change state or even
721
722
723
724
725
726
                                enter the '<literal>failed</literal>'
                                mode. This value defaults to 0 (job
                                timeouts disabled), except for device
                                units. NB: this timeout is independent
                                from any unit-specific timeout (for
                                example, the timeout set with
727
                                <varname>Timeout=</varname> in service
728
729
730
731
                                units) as the job timeout has no
                                effect on the unit itself, only on the
                                job that might be pending for it. Or
                                in other words: unit-specific timeouts
732
733
734
                                are useful to abort unit state
                                changes, and revert them. The job
                                timeout set with this option however
735
736
737
                                is useful to abort only the job
                                waiting for the unit state to
                                change.</para></listitem>
738
739
                        </varlistentry>

740
741
                        <varlistentry>
                                <term><varname>ConditionPathExists=</varname></term>
742
                                <term><varname>ConditionPathExistsGlob=</varname></term>
743
                                <term><varname>ConditionPathIsDirectory=</varname></term>
744
                                <term><varname>ConditionPathIsSymbolicLink=</varname></term>
745
                                <term><varname>ConditionPathIsMountPoint=</varname></term>
746
                                <term><varname>ConditionPathIsReadWrite=</varname></term>
747
                                <term><varname>ConditionDirectoryNotEmpty=</varname></term>
748
                                <term><varname>ConditionFileIsExecutable=</varname></term>
749
                                <term><varname>ConditionKernelCommandLine=</varname></term>
750
                                <term><varname>ConditionVirtualization=</varname></term>
751
                                <term><varname>ConditionSecurity=</varname></term>
752
                                <term><varname>ConditionCapability=</varname></term>
753
                                <term><varname>ConditionNull=</varname></term>
754
755
756
757
758

                                <listitem><para>Before starting a unit
                                verify that the specified condition is
                                true. With
                                <varname>ConditionPathExists=</varname>
759
                                a file existence condition can be
760
761
                                checked before a unit is started. If
                                the specified absolute path name does
762
                                not exist, startup of a unit will not
763
764
765
766
767
768
769
770
771
                                actually happen, however the unit is
                                still useful for ordering purposes in
                                this case. The condition is checked at
                                the time the queued start job is to be
                                executed. If the absolute path name
                                passed to
                                <varname>ConditionPathExists=</varname>
                                is prefixed with an exclamation mark
                                (!), the test is negated, and the unit
772
                                is only started if the path does not
773
                                exist.
774
775
776
                                <varname>ConditionPathExistsGlob=</varname>
                                works in a similar way, but checks for
                                the existence of at least one file or
777
                                directory matching the specified
778
779
780
781
782
                                globbing
                                pattern. <varname>ConditionPathIsDirectory=</varname>
                                is similar to
                                <varname>ConditionPathExists=</varname>
                                but verifies whether a certain path
783
                                exists and is a
784
785
786
787
                                directory. <varname>ConditionPathIsSymbolicLink=</varname>
                                is similar to
                                <varname>ConditionPathExists=</varname>
                                but verifies whether a certain path
788
789
                                exists and is a symbolic
                                link. <varname>ConditionPathIsMountPoint=</varname>
790
791
792
793
                                is similar to
                                <varname>ConditionPathExists=</varname>
                                but verifies whether a certain path
                                exists and is a mount
794
795
796
797
798
799
800
                                point. <varname>ConditionPathIsReadWrite=</varname>
                                is similar to
                                <varname>ConditionPathExists=</varname>
                                but verifies whether the underlying
                                file system is read and writable
                                (i.e. not mounted
                                read-only). <varname>ConditionFileIsExecutable=</varname>
801
802
803
804
                                is similar to
                                <varname>ConditionPathExists=</varname>
                                but verifies whether a certain path
                                exists, is a regular file and marked
805
                                executable.
806
807
808
809
                                <varname>ConditionDirectoryNotEmpty=</varname>
                                is similar to
                                <varname>ConditionPathExists=</varname>
                                but verifies whether a certain path
810
811
                                exists and is a non-empty
                                directory. Similarly
812
813
814
815
816
817
                                <varname>ConditionKernelCommandLine=</varname>
                                may be used to check whether a
                                specific kernel command line option is
                                set (or if prefixed with the
                                exclamation mark unset). The argument
                                must either be a single word, or an
Miklos Vajna's avatar
Miklos Vajna committed
818
                                assignment (i.e. two words, separated
819
                                by the equality sign). In the former
820
821
822
823
824
825
                                case the kernel command line is
                                searched for the word appearing as is,
                                or as left hand side of an
                                assignment. In the latter case the
                                exact assignment is looked for with
                                right and left hand side
826
827
828
829
830
831
                                matching. <varname>ConditionVirtualization=</varname>
                                may be used to check whether the
                                system is executed in a virtualized
                                environment and optionally test
                                whether it is a specific
                                implementation. Takes either boolean
832
                                value to check if being executed in
833
834
                                any virtualized environment, or one of
                                <varname>vm</varname> and
835
836
837
                                <varname>container</varname> to test
                                against a specific type of
                                virtualization solution, or one of
838
839
840
841
842
843
                                <varname>qemu</varname>,
                                <varname>kvm</varname>,
                                <varname>vmware</varname>,
                                <varname>microsoft</varname>,
                                <varname>oracle</varname>,
                                <varname>xen</varname>,
844
845
                                <varname>bochs</varname>,
                                <varname>chroot</varname>,
846
847
                                <varname>openvz</varname>,
                                <varname>lxc</varname>,
848
                                <varname>lxc-libvirt</varname>,
849
850
851
852
853
854
855
                                <varname>systemd-nspawn</varname> to
                                test against a specific
                                implementation. If multiple
                                virtualization technologies are nested
                                only the innermost is considered. The
                                test may be negated by prepending an
                                exclamation mark.
856
                                <varname>ConditionSecurity=</varname>
857
858
859
860
861
                                may be used to check whether the given
                                security module is enabled on the
                                system.  Currently the only recognized
                                value is <varname>selinux</varname>.
                                The test may be negated by prepending
862
863
864
865
866
867
868
869
870
871
872
873
874
                                an exclamation
                                mark. <varname>ConditionCapability=</varname>
                                may be used to check whether the given
                                capability exists in the capability
                                bounding set of the service manager
                                (i.e. this does not check whether
                                capability is actually available in
                                the permitted or effective sets, see
                                <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
                                for details). Pass a capability name
                                such as <literal>CAP_MKNOD</literal>,
                                possibly prefixed with an exclamation
                                mark to negate the check. Finally,
875
876
877
878
879
880
881
                                <varname>ConditionNull=</varname> may
                                be used to add a constant condition
                                check value to the unit. It takes a
                                boolean argument. If set to
                                <varname>false</varname> the condition
                                will always fail, otherwise
                                succeed. If multiple conditions are
882
                                specified the unit will be executed if
883
884
885
886
887
888
889
890
891
892
893
894
895
                                all of them apply (i.e. a logical AND
                                is applied). Condition checks can be
                                prefixed with a pipe symbol (|) in
                                which case a condition becomes a
                                triggering condition. If at least one
                                triggering condition is defined for a
                                unit then the unit will be executed if
                                at least one of the triggering
                                conditions apply and all of the
                                non-triggering conditions. If you
                                prefix an argument with the pipe
                                symbol and an exclamation mark the
                                pipe symbol must be passed first, the
896
897
                                exclamation second. Except for
                                <varname>ConditionPathIsSymbolicLink=</varname>,
898
899
                                all path checks follow
                                symlinks.</para></listitem>
900
                        </varlistentry>
901

902
903
904
905
906
907
908
909
910
911
912
913
                        <varlistentry>
                                <term><varname>SourcePath=</varname></term>
                                <listitem><para>A path to a
                                configuration file this unit has been
                                generated from. This is primarily
                                useful for implementation of generator
                                tools that convert configuration from
                                an external configuration file format
                                into native unit files. Thus
                                functionality should not be used in
                                normal units.</para></listitem>
                        </varlistentry>
914
                </variablelist>
915
916
917
918
919
920

                <para>Unit file may include a [Install] section, which
                carries installation information for the unit. This
                section is not interpreted by
                <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
                during runtime. It is used exclusively by the
921
922
923
                <command>enable</command> and
                <command>disable</command> commands of the
                <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
924
                tool during installation of a unit:</para>
925
926
927
928
929

                <variablelist>
                        <varlistentry>
                                <term><varname>Alias=</varname></term>

Lennart Poettering's avatar
Lennart Poettering committed
930
                                <listitem><para>Additional names this
931
932
933
934
935
936
                                unit shall be installed under. The
                                names listed here must have the same
                                suffix (i.e. type) as the unit file
                                name. This option may be specified
                                more than once, in which case all
                                listed names are used. At installation
Kay Sievers's avatar
Kay Sievers committed
937
                                time,
938
                                <command>systemctl enable</command>
939
                                will create symlinks from these names
940
                                to the unit file name.</para></listitem>
941
942
943
944
                        </varlistentry>

                        <varlistentry>
                                <term><varname>WantedBy=</varname></term>
945
                                <term><varname>RequiredBy=</varname></term>
946
947
948

                                <listitem><para>Installs a symlink in
                                the <filename>.wants/</filename>
949
                                resp. <filename>.requires/</filename>
950
951
952
953
                                subdirectory for a unit. This has the
                                effect that when the listed unit name
                                is activated the unit listing it is
                                activated
Lennart Poettering's avatar
Lennart Poettering committed
954
                                too. <command>WantedBy=foo.service</command>
955
956
957
958
959
960
961
962
963
964
965
966
967
968
                                in a service
                                <filename>bar.service</filename> is
                                mostly equivalent to
                                <command>Alias=foo.service.wants/bar.service</command>
                                in the same file.</para></listitem>
                        </varlistentry>

                        <varlistentry>
                                <term><varname>Also=</varname></term>

                                <listitem><para>Additional units to
                                install when this unit is
                                installed. If the user requests
                                installation of a unit with this
969
                                option configured,
970
                                <command>systemctl enable</command>
971
972
973
                                will automatically install units
                                listed in this option as
                                well.</para></listitem>
974
975
976
                        </varlistentry>
                </variablelist>

977
978
979
        </refsect1>

        <refsect1>
Lennart Poettering's avatar
Lennart Poettering committed
980
981
982
                <title>See Also</title>
                <para>
                        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
983
984
985
986
987
988
989
990
991
992
                        <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
993
                        <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
994
995
                        <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
                        <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
Lennart Poettering's avatar
Lennart Poettering committed
996
                </para>
997
998
999
        </refsect1>

</refentry>