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[elogind.git] / man / systemd.service.xml
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9   Copyright 2010 Lennart Poettering
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24
25 <refentry id="systemd.service">
26         <refentryinfo>
27                 <title>systemd.service</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.service</refentrytitle>
42                 <manvolnum>5</manvolnum>
43         </refmeta>
44
45         <refnamediv>
46                 <refname>systemd.service</refname>
47                 <refpurpose>systemd service configuration files</refpurpose>
48         </refnamediv>
49
50         <refsynopsisdiv>
51                 <para><filename>systemd.service</filename></para>
52         </refsynopsisdiv>
53
54         <refsect1>
55                 <title>Description</title>
56
57                 <para>A unit configuration file whose name ends in
58                 <filename>.service</filename> encodes information
59                 about a process controlled and supervised by
60                 systemd.</para>
61
62                 <para>This man page lists the configuration options
63                 specific to this unit type. See
64                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
65                 for the common options of all unit configuration
66                 files. The common configuration items are configured
67                 in the generic <literal>[Unit]</literal> and
68                 <literal>[Install]</literal> sections. The service
69                 specific configuration options are configured in the
70                 <literal>[Service]</literal> section.</para>
71
72                 <para>Additional options are listed in
73                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
74                 which define the execution environment the commands
75                 are executed in.</para>
76
77                 <para>Unless <varname>DefaultDependencies=</varname>
78                 is set to <option>false</option>, service units will
79                 implicitly have dependencies of type
80                 <varname>Requires=</varname> and
81                 <varname>After=</varname> on
82                 <filename>basic.target</filename> as well as
83                 dependencies of type <varname>Conflicts=</varname> and
84                 <varname>Before=</varname> on
85                 <filename>shutdown.target</filename>. These ensure
86                 that normal service units pull in basic system
87                 initialization, and are terminated cleanly prior to
88                 system shutdown. Only services involved with early
89                 boot or late system shutdown should disable this
90                 option.</para>
91
92                 <para>If a service is requested under a certain name
93                 but no unit configuration file is found, systemd looks
94                 for a SysV init script by the same name (with the
95                 <filename>.service</filename> suffix removed) and
96                 dynamically creates a service unit from that
97                 script. This is useful for compatibility with
98                 SysV.</para>
99         </refsect1>
100
101         <refsect1>
102                 <title>Options</title>
103
104                 <para>Service files must include a
105                 <literal>[Service]</literal> section, which carries
106                 information about the service and the process it
107                 supervises. A number of options that may be used in
108                 this section are shared with other unit types. These
109                 options are documented in
110                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
111                 options specific to the <literal>[Service]</literal>
112                 section of service units are the following:</para>
113
114                 <variablelist>
115                         <varlistentry>
116                                 <term><varname>Type=</varname></term>
117
118                                 <listitem><para>Configures the process
119                                 start-up type for this service
120                                 unit. One of <option>simple</option>,
121                                 <option>forking</option>,
122                                 <option>finish</option>,
123                                 <option>dbus</option>,
124                                 <option>notify</option>.</para>
125
126                                 <para>If set to
127                                 <option>simple</option> (the default
128                                 value) it is expected that the process
129                                 configured with
130                                 <varname>ExecStart=</varname> is the
131                                 main process of the service. In this
132                                 mode, communication channels must be
133                                 installed before the daemon is started
134                                 up (e.g. sockets set up by systemd,
135                                 via socket activation), as systemd
136                                 will immediately proceed starting
137                                 follow-up units.</para>
138
139                                 <para>If set to
140                                 <option>forking</option> it is
141                                 expected that the process configured
142                                 with <varname>ExecStart=</varname>
143                                 will start up and call
144                                 <function>fork()</function>. The
145                                 parent process is expected to finish
146                                 when start-up is complete and all
147                                 communication channels set up. The
148                                 child continues to run as the main
149                                 daemon process. This is the behaviour
150                                 of traditional UNIX daemons. If this
151                                 setting is used, it is recommended to
152                                 also use the
153                                 <varname>PIDFile=</varname> option, so
154                                 that systemd can identify the main
155                                 process of the daemon. systemd will
156                                 proceed starting follow-up units as
157                                 soon as the parent process
158                                 exits.</para>
159
160                                 <para>Behaviour of
161                                 <option>finish</option> is similar
162                                 to <option>simple</option>, however
163                                 it is expected that the process has to
164                                 exit before systemd starts follow-up
165                                 units. <varname>ValidNoProcess=</varname>
166                                 is particularly useful for this type
167                                 of service.</para>
168
169                                 <para>Behaviour of
170                                 <option>dbus</option> is similar to
171                                 <option>simple</option>, however it is
172                                 expected that the daemon acquires a
173                                 name on the D-Bus bus, as configured
174                                 by
175                                 <varname>BusName=</varname>. systemd
176                                 will proceed starting follow-up units
177                                 after the D-Bus bus name has been
178                                 acquired. Service units with this
179                                 option configured implicitly have
180                                 dependencies on the
181                                 <filename>dbus.target</filename>
182                                 unit.</para>
183
184                                 <para>Behaviour of
185                                 <option>notify</option> is similar to
186                                 <option>simple</option>, however it is
187                                 expected that the daemon sends a
188                                 notification message via
189                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
190                                 or an equivalent call when it finished
191                                 starting up. systemd will proceed
192                                 starting follow-up units after this
193                                 notification message has been sent. If
194                                 this option is used
195                                 <varname>NotifyAccess=</varname> (see
196                                 below) must be set to open access to
197                                 the notification socket provided by
198                                 systemd. If
199                                 <varname>NotifyAccess=</varname> is not
200                                 set, it will be implicitly set to
201                                 <option>main</option>.</para>
202                                 </listitem>
203                         </varlistentry>
204
205                         <varlistentry>
206                                 <term><varname>ValidNoProcess=</varname></term>
207
208                                 <listitem><para>Takes a boolean value
209                                 that specifies whether the service
210                                 shall be considered active even when
211                                 all its processes exited. Defaults to
212                                 <option>no</option>.</para>
213                                 </listitem>
214                         </varlistentry>
215
216                         <varlistentry>
217                                 <term><varname>PIDFile=</varname></term>
218
219                                 <listitem><para>Takes an absolute file
220                                 name pointing to the PID file of this
221                                 daemon. Use of this option is
222                                 recommended for services where
223                                 <varname>Type=</varname> is set to
224                                 <option>forking</option>.</para>
225                                 </listitem>
226                         </varlistentry>
227
228                         <varlistentry>
229                                 <term><varname>BusName=</varname></term>
230
231                                 <listitem><para>Takes a D-Bus bus
232                                 name, where this service is reachable
233                                 as. This option is mandatory for
234                                 services where
235                                 <varname>Type=</varname> is set to
236                                 <option>dbus</option>, but its use
237                                 is otherwise recommended as well if
238                                 the process takes a name on the D-Bus
239                                 bus.</para>
240                                 </listitem>
241                         </varlistentry>
242
243                         <varlistentry>
244                                 <term><varname>ExecStart=</varname></term>
245                                 <listitem><para>Takes a command line
246                                 that is executed when this service
247                                 shall be started up. The first token
248                                 of the command line must be an
249                                 absolute file name, then followed by
250                                 arguments for the process. It is
251                                 mandatory to set this option for all
252                                 services. This option may not be
253                                 specified more than once. Optionally,
254                                 if the absolute file name is prefixed
255                                 with <literal>@</literal>, the second
256                                 token will be passed as
257                                 <literal>argv[0]</literal> to the
258                                 executed process, followed by the
259                                 further arguments specified. If the
260                                 first token is prefixed with
261                                 <literal>-</literal> an error code of
262                                 the command normally considered a
263                                 failure is ignored and considered
264                                 success. If both <literal>-</literal>
265                                 and <literal>@</literal> are used for
266                                 the same command the latter must
267                                 preceed the latter. Unless
268                                 <varname>Type=forking</varname> is
269                                 set, the process started via this
270                                 command line will be considered the
271                                 main process of the daemon. The
272                                 command line accepts % specifiers as
273                                 described in
274                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. On
275                                 top of that basic environment variable
276                                 substitution is supported, where
277                                 <literal>$(FOO)</literal> is replaced
278                                 by the value of the environment
279                                 variable of the same
280                                 name.</para></listitem>
281                         </varlistentry>
282
283                         <varlistentry>
284                                 <term><varname>ExecStartPre=</varname></term>
285                                 <term><varname>ExecStartPost=</varname></term>
286                                 <listitem><para>Additional commands
287                                 that are executed before (resp. after)
288                                 the command in
289                                 <varname>ExecStart=</varname>. Multiple
290                                 command lines may be concatenated in a
291                                 single directive, by seperating them
292                                 by semicolons (these semicolons must
293                                 be passed as seperate words). In that
294                                 case, the commands are executed one
295                                 after the other,
296                                 serially. Alternatively, these
297                                 directives may be specified more than
298                                 once whith the same effect. However,
299                                 the latter syntax is not recommended
300                                 for compatibility with parsers
301                                 suitable for XDG
302                                 <filename>.desktop</filename> files.
303                                 Use of these settings is
304                                 optional. Specifier and environment
305                                 variable substitution is
306                                 supported.</para></listitem>
307                         </varlistentry>
308
309                         <varlistentry>
310                                 <term><varname>ExecReload=</varname></term>
311                                 <listitem><para>Commands to execute to
312                                 trigger a configuration reload in the
313                                 service. This argument takes multiple
314                                 command lines, following the same
315                                 scheme as pointed out for
316                                 <varname>ExecStartPre=</varname>
317                                 above. Use of this setting is
318                                 optional. Specifier and environment
319                                 variable substitution is supported
320                                 here following the same scheme as for
321                                 <varname>ExecStart=</varname>. One
322                                 special environment variable is set:
323                                 if known <literal>$MAINPID</literal> is
324                                 set to the main process of the
325                                 daemon, and may be used for command
326                                 lines like the following:
327                                 <command>/bin/kill -HUP
328                                 $(MAINPID)</command>.</para></listitem>
329                         </varlistentry>
330
331                         <varlistentry>
332                                 <term><varname>ExecStop=</varname></term>
333                                 <listitem><para>Commands to execute to
334                                 stop the service started via
335                                 <varname>ExecStart=</varname>. This
336                                 argument takes multiple command lines,
337                                 following the same scheme as pointed
338                                 out for
339                                 <varname>ExecStartPre=</varname>
340                                 above. Use of this setting is
341                                 optional. All processes remaining for
342                                 a service after the commands
343                                 configured in this option are run are
344                                 terminated according to the
345                                 <varname>KillMode=</varname> setting
346                                 (see below). If this option is not
347                                 specified the process is terminated
348                                 right-away when service stop is
349                                 requested. Specifier and environment
350                                 variable substitution is supported
351                                 (including
352                                 <literal>$(MAINPID)</literal>, see
353                                 above).</para></listitem>
354                         </varlistentry>
355
356                         <varlistentry>
357                                 <term><varname>ExecStopPost=</varname></term>
358                                 <listitem><para>Additional commands
359                                 that are executed after the service
360                                 was stopped using the commands
361                                 configured in
362                                 <varname>ExecStop=</varname>. This
363                                 argument takes multiple command lines,
364                                 following the same scheme as pointed
365                                 out for
366                                 <varname>ExecStartPre</varname>. Use
367                                 of these settings is
368                                 optional. Specifier and environment
369                                 variable substitution is
370                                 supported.</para></listitem>
371                         </varlistentry>
372
373                         <varlistentry>
374                                 <term><varname>RestartSec=</varname></term>
375                                 <listitem><para>Configures the time to
376                                 sleep before restarting a service (as
377                                 configured with
378                                 <varname>Restart=</varname>). Takes a
379                                 unit-less value in seconds, or a time
380                                 span value such as "5min
381                                 20s". Defaults to
382                                 100ms.</para></listitem>
383                         </varlistentry>
384
385                         <varlistentry>
386                                 <term><varname>TimeoutSec=</varname></term>
387                                 <listitem><para>Configures the time to
388                                 wait for start-up and stop. If a
389                                 daemon service does not signal
390                                 start-up completion within the
391                                 configured time the service will be
392                                 considered failed and be shut down
393                                 again. If a service is asked to stop
394                                 but does not terminate in the
395                                 specified time it will be terminated
396                                 forcibly via SIGTERM, and after
397                                 another delay of this time with
398                                 SIGKILL. (See
399                                 <varname>KillMode=</varname>
400                                 below.) Takes a unit-less value in seconds, or a
401                                 time span value such as "5min
402                                 20s". Pass 0 to disable the timeout
403                                 logic. Defaults to
404                                 60s.</para></listitem>
405                         </varlistentry>
406
407                         <varlistentry>
408                                 <term><varname>Restart=</varname></term>
409                                 <listitem><para>Configures whether the
410                                 main service process shall be restarted when
411                                 it exists. Takes one of
412                                 <option>once</option>,
413                                 <option>restart-on-success</option> or
414                                 <option>restart-always</option>. If
415                                 set to <option>once</option> (the
416                                 default) the service will not be
417                                 restarted when it exits. If set to
418                                 <option>restart-on-success</option> it
419                                 will be restarted only when it exited
420                                 cleanly, i.e. terminated with an exit
421                                 code of 0. If set to
422                                 <option>restart-always</option> the
423                                 service will be restarted regardless
424                                 whether it exited cleanly or not, or
425                                 got terminated abnormally by a
426                                 signal.</para></listitem>
427                         </varlistentry>
428
429                         <varlistentry>
430                                 <term><varname>PermissionsStartOnly=</varname></term>
431                                 <listitem><para>Takes a boolean
432                                 argument. If true, the permission
433                                 related execution options as
434                                 configured with
435                                 <varname>User=</varname> and similar
436                                 options (see
437                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
438                                 for more information) are only applied
439                                 to the process started with
440                                 <varname>ExecStart=</varname>, and not
441                                 to the various other
442                                 <varname>ExecStartPre=</varname>,
443                                 <varname>ExecStartPost=</varname>,
444                                 <varname>ExecReload=</varname>,
445                                 <varname>ExecStop=</varname>,
446                                 <varname>ExecStopPost=</varname>
447                                 commands. If false, the setting is
448                                 applied to all configured commands the
449                                 same way. Defaults to
450                                 false.</para></listitem>
451                         </varlistentry>
452
453                         <varlistentry>
454                                 <term><varname>RootDirectoryStartOnly=</varname></term>
455                                 <listitem><para>Takes a boolean
456                                 argument. If true, the root directory
457                                 as configured with the
458                                 <varname>RootDirectory=</varname>
459                                 option (see
460                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
461                                 for more information) is only applied
462                                 to the process started with
463                                 <varname>ExecStart=</varname>, and not
464                                 to the various other
465                                 <varname>ExecStartPre=</varname>,
466                                 <varname>ExecStartPost=</varname>,
467                                 <varname>ExecReload=</varname>,
468                                 <varname>ExecStop=</varname>,
469                                 <varname>ExecStopPost=</varname>
470                                 commands. If false, the setting is
471                                 applied to all configured commands the
472                                 same way. Defaults to
473                                 false.</para></listitem>
474                         </varlistentry>
475
476                         <varlistentry>
477                                 <term><varname>SysVStartPriority=</varname></term>
478                                 <listitem><para>Set the SysV start
479                                 priority to use to order this service
480                                 in relation to SysV services lacking
481                                 LSB headers. This option is only
482                                 necessary to fix ordering in relation
483                                 to legacy SysV services, that have no
484                                 ordering information encoded in the
485                                 script headers. As such it should only
486                                 be used as temporary compatibility
487                                 option, and not be used in new unit
488                                 files. Almost always it is a better
489                                 choice to add explicit ordering
490                                 directives via
491                                 <varname>After=</varname> or
492                                 <varname>Before=</varname>,
493                                 instead. For more details see
494                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
495                                 used, pass an integer value in the
496                                 range 0-99.</para></listitem>
497                         </varlistentry>
498
499                         <varlistentry>
500                                 <term><varname>KillMode=</varname></term>
501                                 <listitem><para>Specifies how
502                                 processes of this service shall be
503                                 killed. One of
504                                 <option>control-group</option>,
505                                 <option>process-group</option>,
506                                 <option>process</option>,
507                                 <option>none</option>.</para>
508
509                                 <para>If set to
510                                 <option>control-group</option> all
511                                 remaining processes in the control
512                                 group of this service will be
513                                 terminated on service stop, after the
514                                 stop command (as configured with
515                                 <varname>ExecStop=</varname>) is
516                                 executed. If set to
517                                 <option>process-group</option> only
518                                 the members of the process group of
519                                 the main service process are
520                                 killed. If set to
521                                 <option>process</option> only the main
522                                 process itself is killed. If set to
523                                 <option>none</option> no process is
524                                 killed. In this case only the stop
525                                 command will be executed on service
526                                 stop, but no process be killed
527                                 otherwise. Processes remaining alive
528                                 after stop are left in their control
529                                 group and the control group continues
530                                 to exist after stop unless it is
531                                 empty. Defaults to
532                                 <option>control-croup</option>.</para>
533
534                                 <para>Processes will first be
535                                 terminated via SIGTERM. If then after
536                                 a delay (configured via the
537                                 <varname>TimeoutSec=</varname> option)
538                                 processes still remain, the
539                                 termination request is repeated with
540                                 the SIGKILL signal. See
541                                 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
542                                 for more
543                                 information.</para></listitem>
544                         </varlistentry>
545
546                         <varlistentry>
547                                 <term><varname>NonBlocking=</varname></term>
548                                 <listitem><para>Set O_NONBLOCK flag
549                                 for all file descriptors passed via
550                                 socket-based activation. If true, all
551                                 file descriptors >= 3 (i.e. all except
552                                 STDIN/STDOUT/STDERR) will have
553                                 the O_NONBLOCK flag set and hence are in
554                                 non-blocking mode. This option is only
555                                 useful in conjunction with a socket
556                                 unit, as described in
557                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
558                                 to false.</para></listitem>
559                         </varlistentry>
560
561                         <varlistentry>
562                                 <term><varname>NotifyAccess=</varname></term>
563                                 <listitem><para>Controls access to the
564                                 service status notification socket, as
565                                 accessible via the
566                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
567                                 call. Takes one of
568                                 <option>none</option> (the default),
569                                 <option>main</option> or
570                                 <option>all</option>. If
571                                 <option>none</option> no daemon status
572                                 updates are accepted by the service
573                                 processes, all status update messages
574                                 are ignored. If <option>main</option>
575                                 only service updates sent from the
576                                 main process of the service are
577                                 accepted. If <option>all</option> all
578                                 services updates from all members of
579                                 the service's control group are
580                                 accepted. This option must be set to
581                                 open access to the notification socket
582                                 when using
583                                 <varname>Type=notify</varname> (see above).</para></listitem>
584                         </varlistentry>
585
586                 </variablelist>
587         </refsect1>
588
589         <refsect1>
590                   <title>See Also</title>
591                   <para>
592                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
593                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
594                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
595                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
596                   </para>
597         </refsect1>
598
599 </refentry>