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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
12 under the terms of the GNU General Public License as published by
13 the Free Software Foundation; either version 2 of the License, or
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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 set,
261 the process started via this command
262 line will be considered the main
264 daemon.</para></listitem>
268 <term><varname>ExecStartPre=</varname></term>
269 <term><varname>ExecStartPost=</varname></term>
270 <listitem><para>Additional commands
271 that are executed before (resp. after)
273 <varname>ExecStart=</varname>. Multiple
274 command lines may be concatenated in a
275 single directive, by seperating them
276 by semicolons (these semicolons must
277 be passed as seperate words). In that
278 case, the commands are executed one
280 serially. Alternatively, these
281 directives may be specified more than
282 once whith the same effect. However,
283 the latter syntax is not recommended
284 for compatibility with parsers
286 <filename>.desktop</filename> files.
287 Use of these settings is
288 optional.</para></listitem>
292 <term><varname>ExecReload=</varname></term>
293 <listitem><para>Commands to execute to
294 trigger a configuration reload in the
295 service. This argument takes multiple
296 command lines, following the same
297 scheme as pointed out for
298 <varname>ExecStartPre=</varname>
299 above. Use of this setting is
300 optional. </para></listitem>
304 <term><varname>ExecStop=</varname></term>
305 <listitem><para>Commands to execute to
306 stop the service started via
307 <varname>ExecStart=</varname>. This
308 argument takes multiple command lines,
309 following the same scheme as pointed
311 <varname>ExecStartPre=</varname>
312 above. Use of this setting is
313 optional. All processes remaining for
314 a service after the commands
315 configured in this option are run are
316 terminated according to the
317 <varname>KillMode=</varname> setting
318 (see below). If this option is not
319 specified the process is terminated
320 right-away when service stop is
321 requested.</para></listitem>
325 <term><varname>ExecStopPost=</varname></term>
326 <listitem><para>Additional commands
327 that are executed after the service
328 was stopped using the commands
330 <varname>ExecStop=</varname>. This
331 argument takes multiple command lines,
332 following the same scheme as pointed
334 <varname>ExecStartPre</varname>. Use
336 optional.</para></listitem>
340 <term><varname>RestartSec=</varname></term>
341 <listitem><para>Configures the time to
342 sleep before restarting a service (as
344 <varname>Restart=</varname>). Takes a
345 unit-less value in seconds, or a time
346 span value such as "5min
348 100ms.</para></listitem>
352 <term><varname>TimeoutSec=</varname></term>
353 <listitem><para>Configures the time to
354 wait for start-up and stop. If a
355 daemon service does not signal
356 start-up completion within the
357 configured time the service will be
358 considered failed and be shut down
359 again. If a service is asked to stop
360 but does not terminate in the
361 specified time it will be terminated
362 forcibly via SIGTERM, and after
363 another delay of this time with
365 <varname>KillMode=</varname>
366 below.) Takes a unit-less value in seconds, or a
367 time span value such as "5min
368 20s". Pass 0 to disable the timeout
370 60s.</para></listitem>
374 <term><varname>Restart=</varname></term>
375 <listitem><para>Configures whether the
376 main service process shall be restarted when
377 it exists. Takes one of
378 <option>once</option>,
379 <option>restart-on-success</option> or
380 <option>restart-always</option>. If
381 set to <option>once</option> (the
382 default) the service will not be
383 restarted when it exits. If set to
384 <option>restart-on-success</option> it
385 will be restarted only when it exited
386 cleanly, i.e. terminated with an exit
388 <option>restart-always</option> the
389 service will be restarted regardless
390 whether it exited cleanly or not, or
391 got terminated abnormally by a
392 signal.</para></listitem>
396 <term><varname>PermissionsStartOnly=</varname></term>
397 <listitem><para>Takes a boolean
398 argument. If true, the permission
399 related execution options as
401 <varname>User=</varname> and similar
403 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
404 for more information) are only applied
405 to the process started with
406 <varname>ExecStart=</varname>, and not
408 <varname>ExecStartPre=</varname>,
409 <varname>ExecStartPost=</varname>,
410 <varname>ExecReload=</varname>,
411 <varname>ExecStop=</varname>,
412 <varname>ExecStopPost=</varname>
413 commands. If false, the setting is
414 applied to all configured commands the
415 same way. Defaults to
416 false.</para></listitem>
420 <term><varname>RootDirectoryStartOnly=</varname></term>
421 <listitem><para>Takes a boolean
422 argument. If true, the root directory
423 as configured with the
424 <varname>RootDirectory=</varname>
426 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
427 for more information) is only applied
428 to the process started with
429 <varname>ExecStart=</varname>, and not
431 <varname>ExecStartPre=</varname>,
432 <varname>ExecStartPost=</varname>,
433 <varname>ExecReload=</varname>,
434 <varname>ExecStop=</varname>,
435 <varname>ExecStopPost=</varname>
436 commands. If false, the setting is
437 applied to all configured commands the
438 same way. Defaults to
439 false.</para></listitem>
443 <term><varname>SysVStartPriority=</varname></term>
444 <listitem><para>Set the SysV start
445 priority to use to order this service
446 in relation to SysV services lacking
447 LSB headers. This option is only
448 necessary to fix ordering in relation
449 to legacy SysV services, that have no
450 ordering information encoded in the
451 script headers. As such it should only
452 be used as temporary compatibility
453 option, and not be used in new unit
454 files. Almost always it is a better
455 choice to add explicit ordering
457 <varname>After=</varname> or
458 <varname>Before=</varname>,
459 instead. For more details see
460 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
461 used, pass an integer value in the
462 range 0-99.</para></listitem>
466 <term><varname>KillMode=</varname></term>
467 <listitem><para>Specifies how
468 processes of this service shall be
470 <option>control-group</option>,
471 <option>process-group</option>,
472 <option>process</option>,
473 <option>none</option>.</para>
476 <option>control-group</option> all
477 remaining processes in the control
478 group of this service will be
479 terminated on service stop, after the
480 stop command (as configured with
481 <varname>ExecStop=</varname>) is
483 <option>process-group</option> only
484 the members of the process group of
485 the main service process are
487 <option>process</option> only the main
488 process itself is killed. If set to
489 <option>none</option> no process is
490 killed. In this case only the stop
491 command will be executed on service
492 stop, but no process be killed
493 otherwise. Processes remaining alive
494 after stop are left in their control
495 group and the control group continues
496 to exist after stop unless it is
498 <option>control-croup</option>.</para>
500 <para>Processes will first be
501 terminated via SIGTERM. If then after
502 a delay (configured via the
503 <varname>TimeoutSec=</varname> option)
504 processes still remain, the
505 termination request is repeated with
506 the SIGKILL signal. See
507 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
509 information.</para></listitem>
513 <term><varname>NonBlocking=</varname></term>
514 <listitem><para>Set O_NONBLOCK flag
515 for all file descriptors passed via
516 socket-based activation. If true, all
517 file descriptors >= 3 (i.e. all except
518 STDIN/STDOUT/STDERR) will have
519 the O_NONBLOCK flag set and hence are in
520 non-blocking mode. This option is only
521 useful in conjunction with a socket
522 unit, as described in
523 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
524 to false.</para></listitem>
528 <term><varname>NotifyAccess=</varname></term>
529 <listitem><para>Controls access to the
530 service status notification socket, as
532 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
534 <option>none</option> (the default),
535 <option>main</option> or
536 <option>all</option>. If
537 <option>none</option> no daemon status
538 updates are accepted by the service
539 processes, all status update messages
540 are ignored. If <option>main</option>
541 only service updates sent from the
542 main process of the service are
543 accepted. If <option>all</option> all
544 services updates from all members of
545 the service's control group are
546 accepted. This option must be set to
547 open access to the notification socket
549 <varname>Type=notify</varname> (see above).</para></listitem>
556 <title>See Also</title>
558 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
559 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
560 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
561 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>