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vconsole: more completely cover fedora legacy vconsole configuration
[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>oneshot</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, if the process offers
133                                 functionality to other processes on
134                                 the system its communication channels
135                                 should be installed before the daemon
136                                 is started up (e.g. sockets set up by
137                                 systemd, via socket activation), as
138                                 systemd will immediately proceed
139                                 starting follow-up units.</para>
140
141                                 <para>If set to
142                                 <option>forking</option> it is
143                                 expected that the process configured
144                                 with <varname>ExecStart=</varname>
145                                 will call <function>fork()</function>
146                                 as part of its start-up. The parent process is
147                                 expected to exit when start-up is
148                                 complete and all communication
149                                 channels set up. The child continues
150                                 to run as the main daemon
151                                 process. This is the behaviour of
152                                 traditional UNIX daemons. If this
153                                 setting is used, it is recommended to
154                                 also use the
155                                 <varname>PIDFile=</varname> option, so
156                                 that systemd can identify the main
157                                 process of the daemon. systemd will
158                                 proceed starting follow-up units as
159                                 soon as the parent process
160                                 exits.</para>
161
162                                 <para>Behaviour of
163                                 <option>oneshot</option> is similar
164                                 to <option>simple</option>, however
165                                 it is expected that the process has to
166                                 exit before systemd starts follow-up
167                                 units. <varname>RemainAfterExit=</varname>
168                                 is particularly useful for this type
169                                 of service.</para>
170
171                                 <para>Behaviour of
172                                 <option>dbus</option> is similar to
173                                 <option>simple</option>, however it is
174                                 expected that the daemon acquires a
175                                 name on the D-Bus bus, as configured
176                                 by
177                                 <varname>BusName=</varname>. systemd
178                                 will proceed starting follow-up units
179                                 after the D-Bus bus name has been
180                                 acquired. Service units with this
181                                 option configured implicitly gain
182                                 dependencies on the
183                                 <filename>dbus.target</filename>
184                                 unit.</para>
185
186                                 <para>Behaviour of
187                                 <option>notify</option> is similar to
188                                 <option>simple</option>, however it is
189                                 expected that the daemon sends a
190                                 notification message via
191                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
192                                 or an equivalent call when it finished
193                                 starting up. systemd will proceed
194                                 starting follow-up units after this
195                                 notification message has been sent. If
196                                 this option is used
197                                 <varname>NotifyAccess=</varname> (see
198                                 below) should be set to open access to
199                                 the notification socket provided by
200                                 systemd. If
201                                 <varname>NotifyAccess=</varname> is not
202                                 set, it will implicitly be set to
203                                 <option>main</option>.</para>
204                                 </listitem>
205                         </varlistentry>
206
207                         <varlistentry>
208                                 <term><varname>RemainAfterExit=</varname></term>
209
210                                 <listitem><para>Takes a boolean value
211                                 that specifies whether the service
212                                 shall be considered active even when
213                                 all its processes exited. Defaults to
214                                 <option>no</option>.</para>
215                                 </listitem>
216                         </varlistentry>
217
218                         <varlistentry>
219                                 <term><varname>PIDFile=</varname></term>
220
221                                 <listitem><para>Takes an absolute file
222                                 name pointing to the PID file of this
223                                 daemon. Use of this option is
224                                 recommended for services where
225                                 <varname>Type=</varname> is set to
226                                 <option>forking</option>.</para>
227                                 </listitem>
228                         </varlistentry>
229
230                         <varlistentry>
231                                 <term><varname>BusName=</varname></term>
232
233                                 <listitem><para>Takes a D-Bus bus
234                                 name, where this service is reachable
235                                 as. This option is mandatory for
236                                 services where
237                                 <varname>Type=</varname> is set to
238                                 <option>dbus</option>, but its use
239                                 is otherwise recommended as well if
240                                 the process takes a name on the D-Bus
241                                 bus.</para>
242                                 </listitem>
243                         </varlistentry>
244
245                         <varlistentry>
246                                 <term><varname>ExecStart=</varname></term>
247                                 <listitem><para>Takes a command line
248                                 that is executed when this service
249                                 shall be started up. The first token
250                                 of the command line must be an
251                                 absolute file name, then followed by
252                                 arguments for the process. It is
253                                 mandatory to set this option for all
254                                 services. This option may not be
255                                 specified more than once, except when
256                                 <varname>Type=oneshot</varname> is
257                                 used in which case more than one
258                                 <varname>ExecStart=</varname> line is
259                                 accepted which are then invoked one by
260                                 one, sequentially in the order they
261                                 appear in the unit file.</para>
262
263                                 <para>Optionally, if the absolute file
264                                 name is prefixed with
265                                 <literal>@</literal>, the second token
266                                 will be passed as
267                                 <literal>argv[0]</literal> to the
268                                 executed process, followed by the
269                                 further arguments specified. If the
270                                 first token is prefixed with
271                                 <literal>-</literal> an exit code of
272                                 the command normally considered a
273                                 failure (i.e. non-zero exit status or
274                                 abormal exit due to signal) is ignored
275                                 and considered success. If both
276                                 <literal>-</literal> and
277                                 <literal>@</literal> are used for the
278                                 same command the former must preceed
279                                 the latter. Unless
280                                 <varname>Type=forking</varname> is
281                                 set, the process started via this
282                                 command line will be considered the
283                                 main process of the daemon. The
284                                 command line accepts % specifiers as
285                                 described in
286                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. On
287                                 top of that basic environment variable
288                                 substitution is supported, where
289                                 <literal>${FOO}</literal> is replaced
290                                 by the string value of the environment
291                                 variable of the same name. Also
292                                 <literal>$FOO</literal> may appear as
293                                 separate word on the command line in
294                                 which case the variable is replaced by
295                                 its value split at whitespaces. Note
296                                 that the first argument (i.e. the
297                                 binary to execute) may not be a
298                                 variable, and must be a literal and
299                                 absolute path name.</para></listitem>
300                         </varlistentry>
301
302                         <varlistentry>
303                                 <term><varname>ExecStartPre=</varname></term>
304                                 <term><varname>ExecStartPost=</varname></term>
305                                 <listitem><para>Additional commands
306                                 that are executed before (resp. after)
307                                 the command in
308                                 <varname>ExecStart=</varname>. Multiple
309                                 command lines may be concatenated in a
310                                 single directive, by seperating them
311                                 by semicolons (these semicolons must
312                                 be passed as separate words). In that
313                                 case, the commands are executed one
314                                 after the other,
315                                 serially. Alternatively, these
316                                 directives may be specified more than
317                                 once whith the same effect. However,
318                                 the latter syntax is not recommended
319                                 for compatibility with parsers
320                                 suitable for XDG
321                                 <filename>.desktop</filename> files.
322                                 Use of these settings is
323                                 optional. Specifier and environment
324                                 variable substitution is
325                                 supported.</para></listitem>
326                         </varlistentry>
327
328                         <varlistentry>
329                                 <term><varname>ExecReload=</varname></term>
330                                 <listitem><para>Commands to execute to
331                                 trigger a configuration reload in the
332                                 service. This argument takes multiple
333                                 command lines, following the same
334                                 scheme as pointed out for
335                                 <varname>ExecStartPre=</varname>
336                                 above. Use of this setting is
337                                 optional. Specifier and environment
338                                 variable substitution is supported
339                                 here following the same scheme as for
340                                 <varname>ExecStart=</varname>. One
341                                 special environment variable is set:
342                                 if known <literal>$MAINPID</literal> is
343                                 set to the main process of the
344                                 daemon, and may be used for command
345                                 lines like the following:
346                                 <command>/bin/kill -HUP
347                                 $(MAINPID)</command>.</para></listitem>
348                         </varlistentry>
349
350                         <varlistentry>
351                                 <term><varname>ExecStop=</varname></term>
352                                 <listitem><para>Commands to execute to
353                                 stop the service started via
354                                 <varname>ExecStart=</varname>. This
355                                 argument takes multiple command lines,
356                                 following the same scheme as pointed
357                                 out for
358                                 <varname>ExecStartPre=</varname>
359                                 above. Use of this setting is
360                                 optional. All processes remaining for
361                                 a service after the commands
362                                 configured in this option are run are
363                                 terminated according to the
364                                 <varname>KillMode=</varname> setting
365                                 (see below). If this option is not
366                                 specified the process is terminated
367                                 right-away when service stop is
368                                 requested. Specifier and environment
369                                 variable substitution is supported
370                                 (including
371                                 <literal>$(MAINPID)</literal>, see
372                                 above).</para></listitem>
373                         </varlistentry>
374
375                         <varlistentry>
376                                 <term><varname>ExecStopPost=</varname></term>
377                                 <listitem><para>Additional commands
378                                 that are executed after the service
379                                 was stopped using the commands
380                                 configured in
381                                 <varname>ExecStop=</varname>. This
382                                 argument takes multiple command lines,
383                                 following the same scheme as pointed
384                                 out for
385                                 <varname>ExecStartPre</varname>. Use
386                                 of these settings is
387                                 optional. Specifier and environment
388                                 variable substitution is
389                                 supported.</para></listitem>
390                         </varlistentry>
391
392                         <varlistentry>
393                                 <term><varname>RestartSec=</varname></term>
394                                 <listitem><para>Configures the time to
395                                 sleep before restarting a service (as
396                                 configured with
397                                 <varname>Restart=</varname>). Takes a
398                                 unit-less value in seconds, or a time
399                                 span value such as "5min
400                                 20s". Defaults to
401                                 100ms.</para></listitem>
402                         </varlistentry>
403
404                         <varlistentry>
405                                 <term><varname>TimeoutSec=</varname></term>
406                                 <listitem><para>Configures the time to
407                                 wait for start-up and stop. If a
408                                 daemon service does not signal
409                                 start-up completion within the
410                                 configured time the service will be
411                                 considered failed and be shut down
412                                 again. If a service is asked to stop
413                                 but does not terminate in the
414                                 specified time it will be terminated
415                                 forcibly via SIGTERM, and after
416                                 another delay of this time with
417                                 SIGKILL. (See
418                                 <varname>KillMode=</varname>
419                                 below.) Takes a unit-less value in seconds, or a
420                                 time span value such as "5min
421                                 20s". Pass 0 to disable the timeout
422                                 logic. Defaults to
423                                 60s.</para></listitem>
424                         </varlistentry>
425
426                         <varlistentry>
427                                 <term><varname>Restart=</varname></term>
428                                 <listitem><para>Configures whether the
429                                 main service process shall be restarted when
430                                 it exists. Takes one of
431                                 <option>once</option>,
432                                 <option>restart-on-success</option> or
433                                 <option>restart-always</option>. If
434                                 set to <option>once</option> (the
435                                 default) the service will not be
436                                 restarted when it exits. If set to
437                                 <option>restart-on-success</option> it
438                                 will be restarted only when it exited
439                                 cleanly, i.e. terminated with an exit
440                                 code of 0. If set to
441                                 <option>restart-always</option> the
442                                 service will be restarted regardless
443                                 whether it exited cleanly or not, or
444                                 got terminated abnormally by a
445                                 signal.</para></listitem>
446                         </varlistentry>
447
448                         <varlistentry>
449                                 <term><varname>PermissionsStartOnly=</varname></term>
450                                 <listitem><para>Takes a boolean
451                                 argument. If true, the permission
452                                 related execution options as
453                                 configured with
454                                 <varname>User=</varname> and similar
455                                 options (see
456                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
457                                 for more information) are only applied
458                                 to the process started with
459                                 <varname>ExecStart=</varname>, and not
460                                 to the various other
461                                 <varname>ExecStartPre=</varname>,
462                                 <varname>ExecStartPost=</varname>,
463                                 <varname>ExecReload=</varname>,
464                                 <varname>ExecStop=</varname>,
465                                 <varname>ExecStopPost=</varname>
466                                 commands. If false, the setting is
467                                 applied to all configured commands the
468                                 same way. Defaults to
469                                 false.</para></listitem>
470                         </varlistentry>
471
472                         <varlistentry>
473                                 <term><varname>RootDirectoryStartOnly=</varname></term>
474                                 <listitem><para>Takes a boolean
475                                 argument. If true, the root directory
476                                 as configured with the
477                                 <varname>RootDirectory=</varname>
478                                 option (see
479                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
480                                 for more information) is only applied
481                                 to the process started with
482                                 <varname>ExecStart=</varname>, and not
483                                 to the various other
484                                 <varname>ExecStartPre=</varname>,
485                                 <varname>ExecStartPost=</varname>,
486                                 <varname>ExecReload=</varname>,
487                                 <varname>ExecStop=</varname>,
488                                 <varname>ExecStopPost=</varname>
489                                 commands. If false, the setting is
490                                 applied to all configured commands the
491                                 same way. Defaults to
492                                 false.</para></listitem>
493                         </varlistentry>
494
495                         <varlistentry>
496                                 <term><varname>SysVStartPriority=</varname></term>
497                                 <listitem><para>Set the SysV start
498                                 priority to use to order this service
499                                 in relation to SysV services lacking
500                                 LSB headers. This option is only
501                                 necessary to fix ordering in relation
502                                 to legacy SysV services, that have no
503                                 ordering information encoded in the
504                                 script headers. As such it should only
505                                 be used as temporary compatibility
506                                 option, and not be used in new unit
507                                 files. Almost always it is a better
508                                 choice to add explicit ordering
509                                 directives via
510                                 <varname>After=</varname> or
511                                 <varname>Before=</varname>,
512                                 instead. For more details see
513                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
514                                 used, pass an integer value in the
515                                 range 0-99.</para></listitem>
516                         </varlistentry>
517
518                         <varlistentry>
519                                 <term><varname>KillMode=</varname></term>
520                                 <listitem><para>Specifies how
521                                 processes of this service shall be
522                                 killed. One of
523                                 <option>control-group</option>,
524                                 <option>process-group</option>,
525                                 <option>process</option>,
526                                 <option>none</option>.</para>
527
528                                 <para>If set to
529                                 <option>control-group</option> all
530                                 remaining processes in the control
531                                 group of this service will be
532                                 terminated on service stop, after the
533                                 stop command (as configured with
534                                 <varname>ExecStop=</varname>) is
535                                 executed. If set to
536                                 <option>process-group</option> only
537                                 the members of the process group of
538                                 the main service process are
539                                 killed. If set to
540                                 <option>process</option> only the main
541                                 process itself is killed. If set to
542                                 <option>none</option> no process is
543                                 killed. In this case only the stop
544                                 command will be executed on service
545                                 stop, but no process be killed
546                                 otherwise. Processes remaining alive
547                                 after stop are left in their control
548                                 group and the control group continues
549                                 to exist after stop unless it is
550                                 empty. Defaults to
551                                 <option>control-croup</option>.</para>
552
553                                 <para>Processes will first be
554                                 terminated via SIGTERM. If then after
555                                 a delay (configured via the
556                                 <varname>TimeoutSec=</varname> option)
557                                 processes still remain, the
558                                 termination request is repeated with
559                                 the SIGKILL signal. See
560                                 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
561                                 for more
562                                 information.</para></listitem>
563                         </varlistentry>
564
565                         <varlistentry>
566                                 <term><varname>NonBlocking=</varname></term>
567                                 <listitem><para>Set O_NONBLOCK flag
568                                 for all file descriptors passed via
569                                 socket-based activation. If true, all
570                                 file descriptors >= 3 (i.e. all except
571                                 STDIN/STDOUT/STDERR) will have
572                                 the O_NONBLOCK flag set and hence are in
573                                 non-blocking mode. This option is only
574                                 useful in conjunction with a socket
575                                 unit, as described in
576                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
577                                 to false.</para></listitem>
578                         </varlistentry>
579
580                         <varlistentry>
581                                 <term><varname>NotifyAccess=</varname></term>
582                                 <listitem><para>Controls access to the
583                                 service status notification socket, as
584                                 accessible via the
585                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
586                                 call. Takes one of
587                                 <option>none</option> (the default),
588                                 <option>main</option> or
589                                 <option>all</option>. If
590                                 <option>none</option> no daemon status
591                                 updates are accepted by the service
592                                 processes, all status update messages
593                                 are ignored. If <option>main</option>
594                                 only service updates sent from the
595                                 main process of the service are
596                                 accepted. If <option>all</option> all
597                                 services updates from all members of
598                                 the service's control group are
599                                 accepted. This option must be set to
600                                 open access to the notification socket
601                                 when using
602                                 <varname>Type=notify</varname> (see above).</para></listitem>
603                         </varlistentry>
604
605                 </variablelist>
606         </refsect1>
607
608         <refsect1>
609                   <title>See Also</title>
610                   <para>
611                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
612                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
613                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
614                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
615                   </para>
616         </refsect1>
617
618 </refentry>