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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. Unless
260                                 <varname>Type=forking</varname> is
261                                 set, the process started via this
262                                 command line will be considered the
263                                 main process of the daemon. The
264                                 command line accepts % specifiers as
265                                 described in
266                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. On
267                                 top of that basic environment variable
268                                 substitution is supported, where
269                                 <literal>$(FOO)</literal> is replaced
270                                 by the value of the environment
271                                 variable of the same
272                                 name.</para></listitem>
273                         </varlistentry>
274
275                         <varlistentry>
276                                 <term><varname>ExecStartPre=</varname></term>
277                                 <term><varname>ExecStartPost=</varname></term>
278                                 <listitem><para>Additional commands
279                                 that are executed before (resp. after)
280                                 the command in
281                                 <varname>ExecStart=</varname>. Multiple
282                                 command lines may be concatenated in a
283                                 single directive, by seperating them
284                                 by semicolons (these semicolons must
285                                 be passed as seperate words). In that
286                                 case, the commands are executed one
287                                 after the other,
288                                 serially. Alternatively, these
289                                 directives may be specified more than
290                                 once whith the same effect. However,
291                                 the latter syntax is not recommended
292                                 for compatibility with parsers
293                                 suitable for XDG
294                                 <filename>.desktop</filename> files.
295                                 Use of these settings is
296                                 optional. Specifier and environment
297                                 variable substitution is
298                                 supported.</para></listitem>
299                         </varlistentry>
300
301                         <varlistentry>
302                                 <term><varname>ExecReload=</varname></term>
303                                 <listitem><para>Commands to execute to
304                                 trigger a configuration reload in the
305                                 service. This argument takes multiple
306                                 command lines, following the same
307                                 scheme as pointed out for
308                                 <varname>ExecStartPre=</varname>
309                                 above. Use of this setting is
310                                 optional. Specifier and environment
311                                 variable substitution is supported
312                                 here following the same scheme as for
313                                 <varname>ExecStart=</varname>. One
314                                 special environment variable is set:
315                                 if known <literal>$MAINPID</literal> is
316                                 set to the main process of the
317                                 daemon, and may be used for command
318                                 lines like the following:
319                                 <command>/bin/kill -HUP
320                                 $(MAINPID)</command>.</para></listitem>
321                         </varlistentry>
322
323                         <varlistentry>
324                                 <term><varname>ExecStop=</varname></term>
325                                 <listitem><para>Commands to execute to
326                                 stop the service started via
327                                 <varname>ExecStart=</varname>. This
328                                 argument takes multiple command lines,
329                                 following the same scheme as pointed
330                                 out for
331                                 <varname>ExecStartPre=</varname>
332                                 above. Use of this setting is
333                                 optional. All processes remaining for
334                                 a service after the commands
335                                 configured in this option are run are
336                                 terminated according to the
337                                 <varname>KillMode=</varname> setting
338                                 (see below). If this option is not
339                                 specified the process is terminated
340                                 right-away when service stop is
341                                 requested. Specifier and environment
342                                 variable substitution is supported
343                                 (including
344                                 <literal>$(MAINPID)</literal>, see
345                                 above).</para></listitem>
346                         </varlistentry>
347
348                         <varlistentry>
349                                 <term><varname>ExecStopPost=</varname></term>
350                                 <listitem><para>Additional commands
351                                 that are executed after the service
352                                 was stopped using the commands
353                                 configured in
354                                 <varname>ExecStop=</varname>. This
355                                 argument takes multiple command lines,
356                                 following the same scheme as pointed
357                                 out for
358                                 <varname>ExecStartPre</varname>. Use
359                                 of these settings is
360                                 optional. Specifier and environment
361                                 variable substitution is
362                                 supported.</para></listitem>
363                         </varlistentry>
364
365                         <varlistentry>
366                                 <term><varname>RestartSec=</varname></term>
367                                 <listitem><para>Configures the time to
368                                 sleep before restarting a service (as
369                                 configured with
370                                 <varname>Restart=</varname>). Takes a
371                                 unit-less value in seconds, or a time
372                                 span value such as "5min
373                                 20s". Defaults to
374                                 100ms.</para></listitem>
375                         </varlistentry>
376
377                         <varlistentry>
378                                 <term><varname>TimeoutSec=</varname></term>
379                                 <listitem><para>Configures the time to
380                                 wait for start-up and stop. If a
381                                 daemon service does not signal
382                                 start-up completion within the
383                                 configured time the service will be
384                                 considered failed and be shut down
385                                 again. If a service is asked to stop
386                                 but does not terminate in the
387                                 specified time it will be terminated
388                                 forcibly via SIGTERM, and after
389                                 another delay of this time with
390                                 SIGKILL. (See
391                                 <varname>KillMode=</varname>
392                                 below.) Takes a unit-less value in seconds, or a
393                                 time span value such as "5min
394                                 20s". Pass 0 to disable the timeout
395                                 logic. Defaults to
396                                 60s.</para></listitem>
397                         </varlistentry>
398
399                         <varlistentry>
400                                 <term><varname>Restart=</varname></term>
401                                 <listitem><para>Configures whether the
402                                 main service process shall be restarted when
403                                 it exists. Takes one of
404                                 <option>once</option>,
405                                 <option>restart-on-success</option> or
406                                 <option>restart-always</option>. If
407                                 set to <option>once</option> (the
408                                 default) the service will not be
409                                 restarted when it exits. If set to
410                                 <option>restart-on-success</option> it
411                                 will be restarted only when it exited
412                                 cleanly, i.e. terminated with an exit
413                                 code of 0. If set to
414                                 <option>restart-always</option> the
415                                 service will be restarted regardless
416                                 whether it exited cleanly or not, or
417                                 got terminated abnormally by a
418                                 signal.</para></listitem>
419                         </varlistentry>
420
421                         <varlistentry>
422                                 <term><varname>PermissionsStartOnly=</varname></term>
423                                 <listitem><para>Takes a boolean
424                                 argument. If true, the permission
425                                 related execution options as
426                                 configured with
427                                 <varname>User=</varname> and similar
428                                 options (see
429                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
430                                 for more information) are only applied
431                                 to the process started with
432                                 <varname>ExecStart=</varname>, and not
433                                 to the various other
434                                 <varname>ExecStartPre=</varname>,
435                                 <varname>ExecStartPost=</varname>,
436                                 <varname>ExecReload=</varname>,
437                                 <varname>ExecStop=</varname>,
438                                 <varname>ExecStopPost=</varname>
439                                 commands. If false, the setting is
440                                 applied to all configured commands the
441                                 same way. Defaults to
442                                 false.</para></listitem>
443                         </varlistentry>
444
445                         <varlistentry>
446                                 <term><varname>RootDirectoryStartOnly=</varname></term>
447                                 <listitem><para>Takes a boolean
448                                 argument. If true, the root directory
449                                 as configured with the
450                                 <varname>RootDirectory=</varname>
451                                 option (see
452                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
453                                 for more information) is only applied
454                                 to the process started with
455                                 <varname>ExecStart=</varname>, and not
456                                 to the various other
457                                 <varname>ExecStartPre=</varname>,
458                                 <varname>ExecStartPost=</varname>,
459                                 <varname>ExecReload=</varname>,
460                                 <varname>ExecStop=</varname>,
461                                 <varname>ExecStopPost=</varname>
462                                 commands. If false, the setting is
463                                 applied to all configured commands the
464                                 same way. Defaults to
465                                 false.</para></listitem>
466                         </varlistentry>
467
468                         <varlistentry>
469                                 <term><varname>SysVStartPriority=</varname></term>
470                                 <listitem><para>Set the SysV start
471                                 priority to use to order this service
472                                 in relation to SysV services lacking
473                                 LSB headers. This option is only
474                                 necessary to fix ordering in relation
475                                 to legacy SysV services, that have no
476                                 ordering information encoded in the
477                                 script headers. As such it should only
478                                 be used as temporary compatibility
479                                 option, and not be used in new unit
480                                 files. Almost always it is a better
481                                 choice to add explicit ordering
482                                 directives via
483                                 <varname>After=</varname> or
484                                 <varname>Before=</varname>,
485                                 instead. For more details see
486                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
487                                 used, pass an integer value in the
488                                 range 0-99.</para></listitem>
489                         </varlistentry>
490
491                         <varlistentry>
492                                 <term><varname>KillMode=</varname></term>
493                                 <listitem><para>Specifies how
494                                 processes of this service shall be
495                                 killed. One of
496                                 <option>control-group</option>,
497                                 <option>process-group</option>,
498                                 <option>process</option>,
499                                 <option>none</option>.</para>
500
501                                 <para>If set to
502                                 <option>control-group</option> all
503                                 remaining processes in the control
504                                 group of this service will be
505                                 terminated on service stop, after the
506                                 stop command (as configured with
507                                 <varname>ExecStop=</varname>) is
508                                 executed. If set to
509                                 <option>process-group</option> only
510                                 the members of the process group of
511                                 the main service process are
512                                 killed. If set to
513                                 <option>process</option> only the main
514                                 process itself is killed. If set to
515                                 <option>none</option> no process is
516                                 killed. In this case only the stop
517                                 command will be executed on service
518                                 stop, but no process be killed
519                                 otherwise. Processes remaining alive
520                                 after stop are left in their control
521                                 group and the control group continues
522                                 to exist after stop unless it is
523                                 empty. Defaults to
524                                 <option>control-croup</option>.</para>
525
526                                 <para>Processes will first be
527                                 terminated via SIGTERM. If then after
528                                 a delay (configured via the
529                                 <varname>TimeoutSec=</varname> option)
530                                 processes still remain, the
531                                 termination request is repeated with
532                                 the SIGKILL signal. See
533                                 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
534                                 for more
535                                 information.</para></listitem>
536                         </varlistentry>
537
538                         <varlistentry>
539                                 <term><varname>NonBlocking=</varname></term>
540                                 <listitem><para>Set O_NONBLOCK flag
541                                 for all file descriptors passed via
542                                 socket-based activation. If true, all
543                                 file descriptors >= 3 (i.e. all except
544                                 STDIN/STDOUT/STDERR) will have
545                                 the O_NONBLOCK flag set and hence are in
546                                 non-blocking mode. This option is only
547                                 useful in conjunction with a socket
548                                 unit, as described in
549                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
550                                 to false.</para></listitem>
551                         </varlistentry>
552
553                         <varlistentry>
554                                 <term><varname>NotifyAccess=</varname></term>
555                                 <listitem><para>Controls access to the
556                                 service status notification socket, as
557                                 accessible via the
558                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
559                                 call. Takes one of
560                                 <option>none</option> (the default),
561                                 <option>main</option> or
562                                 <option>all</option>. If
563                                 <option>none</option> no daemon status
564                                 updates are accepted by the service
565                                 processes, all status update messages
566                                 are ignored. If <option>main</option>
567                                 only service updates sent from the
568                                 main process of the service are
569                                 accepted. If <option>all</option> all
570                                 services updates from all members of
571                                 the service's control group are
572                                 accepted. This option must be set to
573                                 open access to the notification socket
574                                 when using
575                                 <varname>Type=notify</varname> (see above).</para></listitem>
576                         </varlistentry>
577
578                 </variablelist>
579         </refsect1>
580
581         <refsect1>
582                   <title>See Also</title>
583                   <para>
584                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
585                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
586                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
587                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
588                   </para>
589         </refsect1>
590
591 </refentry>