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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
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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>. If
274 specified more than once, all commands
275 are executed one after the other,
276 serially. Use of these settings is
277 optional.</para></listitem>
281 <term><varname>ExecReload=</varname></term>
282 <listitem><para>Commands to execute to
283 trigger a configuration reload in the
284 service. If used more than once, all
285 commands are executed one after the
286 other, serially. Use of this setting is optional.
291 <term><varname>ExecStop=</varname></term>
292 <listitem><para>Commands to execute to
293 stop the service started via
294 <varname>ExecStart=</varname>. If used
295 more than once, all commands are
296 executed one after the other,
297 serially. Use of this setting is
298 optional. All processes remaining for
299 a service after the commands
300 configured in this option are run are
301 terminated according to the
302 <varname>KillMode=</varname> setting
303 (see below). If this option is not
304 specified the process is terminated
305 right-away when service stop is
306 requested.</para></listitem>
310 <term><varname>ExecStopPost=</varname></term>
311 <listitem><para>Additional commands
312 that are executed after the service
313 was stopped using the commands
315 <varname>ExecStop=</varname>. If
316 specified more than once, all commands
317 are executed one after the other,
318 serially. Use of these settings is
319 optional.</para></listitem>
323 <term><varname>RestartSec=</varname></term>
324 <listitem><para>Configures the time to
325 sleep before restarting a service (as
327 <varname>Restart=</varname>). Takes a
328 unit-less value in seconds, or a time
329 span value such as "5min
331 100ms.</para></listitem>
335 <term><varname>TimeoutSec=</varname></term>
336 <listitem><para>Configures the time to
337 wait for start-up and stop. If a
338 daemon service does not signal
339 start-up completion within the
340 configured time the service will be
341 considered failed and be shut down
342 again. If a service is asked to stop
343 but does not terminate in the
344 specified time it will be terminated
345 forcibly via SIGTERM, and after
346 another delay of this time with
348 <varname>KillMode=</varname>
349 below.) Takes a unit-less value in seconds, or a
350 time span value such as "5min
351 20s". Pass 0 to disable the timeout
353 60s.</para></listitem>
357 <term><varname>Restart=</varname></term>
358 <listitem><para>Configures whether the
359 main service process shall be restarted when
360 it exists. Takes one of
361 <option>once</option>,
362 <option>restart-on-success</option> or
363 <option>restart-always</option>. If
364 set to <option>once</option> (the
365 default) the service will not be
366 restarted when it exits. If set to
367 <option>restart-on-success</option> it
368 will be restarted only when it exited
369 cleanly, i.e. terminated with an exit
371 <option>restart-always</option> the
372 service will be restarted regardless
373 whether it exited cleanly or not, or
374 got terminated abnormally by a
375 signal.</para></listitem>
379 <term><varname>PermissionsStartOnly=</varname></term>
380 <listitem><para>Takes a boolean
381 argument. If true, the permission
382 related execution options as
384 <varname>User=</varname> and similar
386 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
387 for more information) are only applied
388 to the process started with
389 <varname>ExecStart=</varname>, and not
391 <varname>ExecStartPre=</varname>,
392 <varname>ExecStartPost=</varname>,
393 <varname>ExecReload=</varname>,
394 <varname>ExecStop=</varname>,
395 <varname>ExecStopPost=</varname>
396 commands. If false, the setting is
397 applied to all configured commands the
398 same way. Defaults to
399 false.</para></listitem>
403 <term><varname>RootDirectoryStartOnly=</varname></term>
404 <listitem><para>Takes a boolean
405 argument. If true, the root directory
406 as configured with the
407 <varname>RootDirectory=</varname>
409 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
410 for more information) is only applied
411 to the process started with
412 <varname>ExecStart=</varname>, and not
414 <varname>ExecStartPre=</varname>,
415 <varname>ExecStartPost=</varname>,
416 <varname>ExecReload=</varname>,
417 <varname>ExecStop=</varname>,
418 <varname>ExecStopPost=</varname>
419 commands. If false, the setting is
420 applied to all configured commands the
421 same way. Defaults to
422 false.</para></listitem>
426 <term><varname>SysVStartPriority=</varname></term>
427 <listitem><para>Set the SysV start
428 priority to use to order this service
429 in relation to SysV services lacking
430 LSB headers. This option is only
431 necessary to fix ordering in relation
432 to legacy SysV services, that have no
433 ordering information encoded in the
434 script headers. As such it should only
435 be used as temporary compatibility
436 option, and not be used in new unit
437 files. Almost always it is a better
438 choice to add explicit ordering
440 <varname>After=</varname> or
441 <varname>Before=</varname>,
442 instead. For more details see
443 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
444 used, pass an integer value in the
445 range 0-99.</para></listitem>
449 <term><varname>KillMode=</varname></term>
450 <listitem><para>Specifies how
451 processes of this service shall be
453 <option>control-group</option>,
454 <option>process-group</option>,
455 <option>process</option>,
456 <option>none</option>.</para>
459 <option>control-group</option> all
460 remaining processes in the control
461 group of this service will be
462 terminated on service stop, after the
463 stop command (as configured with
464 <varname>ExecStop=</varname>) is
466 <option>process-group</option> only
467 the members of the process group of
468 the main service process are
470 <option>process</option> only the main
471 process itself is killed. If set to
472 <option>none</option> no process is
473 killed. In this case only the stop
474 command will be executed on service
475 stop, but no process be killed
476 otherwise. Processes remaining alive
477 after stop are left in their control
478 group and the control group continues
479 to exist after stop unless it is
481 <option>control-croup</option>.</para>
483 <para>Processes will first be
484 terminated via SIGTERM. If then after
485 a delay (configured via the
486 <varname>TimeoutSec=</varname> option)
487 processes still remain, the
488 termination request is repeated with
489 the SIGKILL signal. See
490 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
492 information.</para></listitem>
496 <term><varname>NonBlocking=</varname></term>
497 <listitem><para>Set O_NONBLOCK flag
498 for all file descriptors passed via
499 socket-based activation. If true, all
500 file descriptors >= 3 (i.e. all except
501 STDIN/STDOUT/STDERR) will have
502 the O_NONBLOCK flag set and hence are in
503 non-blocking mode. This option is only
504 useful in conjunction with a socket
505 unit, as described in
506 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
507 to false.</para></listitem>
511 <term><varname>NotifyAccess=</varname></term>
512 <listitem><para>Controls access to the
513 service status notification socket, as
515 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
517 <option>none</option> (the default),
518 <option>main</option> or
519 <option>all</option>. If
520 <option>none</option> no daemon status
521 updates are accepted by the service
522 processes, all status update messages
523 are ignored. If <option>main</option>
524 only service updates sent from the
525 main process of the service are
526 accepted. If <option>all</option> all
527 services updates from all members of
528 the service's control group are
529 accepted. This option must be set to
530 open access to the notification socket
532 <varname>Type=notify</varname> (see above).</para></listitem>
539 <title>See Also</title>
541 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
542 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
543 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
544 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>