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7 This file is part of systemd.
9 Copyright 2010 Lennart Poettering
11 systemd is free software; you can redistribute it and/or modify it
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25 <refentry id="systemd.service">
27 <title>systemd.service</title>
28 <productname>systemd</productname>
32 <contrib>Developer</contrib>
33 <firstname>Lennart</firstname>
34 <surname>Poettering</surname>
35 <email>lennart@poettering.net</email>
41 <refentrytitle>systemd.service</refentrytitle>
42 <manvolnum>5</manvolnum>
46 <refname>systemd.service</refname>
47 <refpurpose>systemd service configuration files</refpurpose>
51 <para><filename>systemd.service</filename></para>
55 <title>Description</title>
57 <para>A unit configuration file whose name ends in
58 <filename>.service</filename> encodes information
59 about a process controlled and supervised by
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>
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>
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
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
102 <title>Options</title>
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>
116 <term><varname>Type=</varname></term>
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>
127 <option>simple</option> (the default
128 value) it is expected that the process
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>
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
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
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
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
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
181 <filename>dbus.target</filename>
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
195 <varname>NotifyAccess=</varname> (see
196 below) must be set to open access to
197 the notification socket provided by
199 <varname>NotifyAccess=</varname> is not
200 set, it will be implicitly set to
201 <option>main</option>.</para>
206 <term><varname>ValidNoProcess=</varname></term>
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>
217 <term><varname>PIDFile=</varname></term>
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>
229 <term><varname>BusName=</varname></term>
231 <listitem><para>Takes a D-Bus bus
232 name, where this service is reachable
233 as. This option is mandatory for
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
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
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>$(FOO)</literal> is replaced
270 by the value of the environment
272 name.</para></listitem>
276 <term><varname>ExecStartPre=</varname></term>
277 <term><varname>ExecStartPost=</varname></term>
278 <listitem><para>Additional commands
279 that are executed before (resp. after)
281 <varname>ExecStart=</varname>. Multiple
282 command lines may be concatenated in a
283 single directive, by seperating them
284 by semicolons (these semicolons must
285 be passed as seperate words). In that
286 case, the commands are executed one
288 serially. Alternatively, these
289 directives may be specified more than
290 once whith the same effect. However,
291 the latter syntax is not recommended
292 for compatibility with parsers
294 <filename>.desktop</filename> files.
295 Use of these settings is
296 optional. Specifier and environment
297 variable substitution is
298 supported.</para></listitem>
302 <term><varname>ExecReload=</varname></term>
303 <listitem><para>Commands to execute to
304 trigger a configuration reload in the
305 service. This argument takes multiple
306 command lines, following the same
307 scheme as pointed out for
308 <varname>ExecStartPre=</varname>
309 above. Use of this setting is
310 optional. Specifier and environment
311 variable substitution is supported
312 here following the same scheme as for
313 <varname>ExecStart=</varname>. One
314 special environment variable is set:
315 if known <literal>$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 $(MAINPID)</command>.</para></listitem>
324 <term><varname>ExecStop=</varname></term>
325 <listitem><para>Commands to execute to
326 stop the service started via
327 <varname>ExecStart=</varname>. This
328 argument takes multiple command lines,
329 following the same scheme as pointed
331 <varname>ExecStartPre=</varname>
332 above. Use of this setting is
333 optional. All processes remaining for
334 a service after the commands
335 configured in this option are run are
336 terminated according to the
337 <varname>KillMode=</varname> setting
338 (see below). If this option is not
339 specified the process is terminated
340 right-away when service stop is
341 requested. Specifier and environment
342 variable substitution is supported
344 <literal>$(MAINPID)</literal>, see
345 above).</para></listitem>
349 <term><varname>ExecStopPost=</varname></term>
350 <listitem><para>Additional commands
351 that are executed after the service
352 was stopped using the commands
354 <varname>ExecStop=</varname>. This
355 argument takes multiple command lines,
356 following the same scheme as pointed
358 <varname>ExecStartPre</varname>. Use
360 optional. Specifier and environment
361 variable substitution is
362 supported.</para></listitem>
366 <term><varname>RestartSec=</varname></term>
367 <listitem><para>Configures the time to
368 sleep before restarting a service (as
370 <varname>Restart=</varname>). Takes a
371 unit-less value in seconds, or a time
372 span value such as "5min
374 100ms.</para></listitem>
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
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
396 60s.</para></listitem>
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
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>
422 <term><varname>PermissionsStartOnly=</varname></term>
423 <listitem><para>Takes a boolean
424 argument. If true, the permission
425 related execution options as
427 <varname>User=</varname> and similar
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
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>
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>
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
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>
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
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>
492 <term><varname>KillMode=</varname></term>
493 <listitem><para>Specifies how
494 processes of this service shall be
496 <option>control-group</option>,
497 <option>process-group</option>,
498 <option>process</option>,
499 <option>none</option>.</para>
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
509 <option>process-group</option> only
510 the members of the process group of
511 the main service process are
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
524 <option>control-croup</option>.</para>
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>
535 information.</para></listitem>
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>
554 <term><varname>NotifyAccess=</varname></term>
555 <listitem><para>Controls access to the
556 service status notification socket, as
558 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
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
575 <varname>Type=notify</varname> (see above).</para></listitem>
582 <title>See Also</title>
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>