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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>oneshot</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, 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>
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
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
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
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
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
183 <filename>dbus.target</filename>
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
197 <varname>NotifyAccess=</varname> (see
198 below) should be set to open access to
199 the notification socket provided by
201 <varname>NotifyAccess=</varname> is not
202 set, it will implicitly be set to
203 <option>main</option>.</para>
208 <term><varname>RemainAfterExit=</varname></term>
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>
219 <term><varname>PIDFile=</varname></term>
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>. systemd will
227 read the PID of the main process of
228 the daemon after start-up of the
229 service. systemd will not write to the
230 file configured here.</para>
235 <term><varname>BusName=</varname></term>
237 <listitem><para>Takes a D-Bus bus
238 name, where this service is reachable
239 as. This option is mandatory for
241 <varname>Type=</varname> is set to
242 <option>dbus</option>, but its use
243 is otherwise recommended as well if
244 the process takes a name on the D-Bus
250 <term><varname>ExecStart=</varname></term>
251 <listitem><para>Takes a command line
252 that is executed when this service
253 shall be started up. The first token
254 of the command line must be an
255 absolute file name, then followed by
256 arguments for the process. It is
257 mandatory to set this option for all
258 services. This option may not be
259 specified more than once, except when
260 <varname>Type=oneshot</varname> is
261 used in which case more than one
262 <varname>ExecStart=</varname> line is
263 accepted which are then invoked one by
264 one, sequentially in the order they
265 appear in the unit file.</para>
267 <para>Optionally, if the absolute file
268 name is prefixed with
269 <literal>@</literal>, the second token
271 <literal>argv[0]</literal> to the
272 executed process, followed by the
273 further arguments specified. If the
274 first token is prefixed with
275 <literal>-</literal> an exit code of
276 the command normally considered a
277 failure (i.e. non-zero exit status or
278 abnormal exit due to signal) is ignored
279 and considered success. If both
280 <literal>-</literal> and
281 <literal>@</literal> are used for the
282 same command the former must precede
284 <varname>Type=forking</varname> is
285 set, the process started via this
286 command line will be considered the
287 main process of the daemon. The
288 command line accepts % specifiers as
290 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. On
291 top of that basic environment variable
292 substitution is supported, where
293 <literal>${FOO}</literal> is replaced
294 by the string value of the environment
295 variable of the same name. Also
296 <literal>$FOO</literal> may appear as
297 separate word on the command line in
298 which case the variable is replaced by
299 its value split at whitespaces. Note
300 that the first argument (i.e. the
301 binary to execute) may not be a
302 variable, and must be a literal and
303 absolute path name.</para></listitem>
307 <term><varname>ExecStartPre=</varname></term>
308 <term><varname>ExecStartPost=</varname></term>
309 <listitem><para>Additional commands
310 that are executed before (resp. after)
312 <varname>ExecStart=</varname>. Multiple
313 command lines may be concatenated in a
314 single directive, by separating them
315 by semicolons (these semicolons must
316 be passed as separate words). In that
317 case, the commands are executed one
319 serially. Alternatively, these
320 directives may be specified more than
321 once with the same effect. However,
322 the latter syntax is not recommended
323 for compatibility with parsers
325 <filename>.desktop</filename> files.
326 Use of these settings is
327 optional. Specifier and environment
328 variable substitution is
329 supported.</para></listitem>
333 <term><varname>ExecReload=</varname></term>
334 <listitem><para>Commands to execute to
335 trigger a configuration reload in the
336 service. This argument takes multiple
337 command lines, following the same
338 scheme as pointed out for
339 <varname>ExecStartPre=</varname>
340 above. Use of this setting is
341 optional. Specifier and environment
342 variable substitution is supported
343 here following the same scheme as for
344 <varname>ExecStart=</varname>. One
345 special environment variable is set:
346 if known <literal>$MAINPID</literal> is
347 set to the main process of the
348 daemon, and may be used for command
349 lines like the following:
350 <command>/bin/kill -HUP
351 $MAINPID</command>.</para></listitem>
355 <term><varname>ExecStop=</varname></term>
356 <listitem><para>Commands to execute to
357 stop the service started via
358 <varname>ExecStart=</varname>. This
359 argument takes multiple command lines,
360 following the same scheme as pointed
362 <varname>ExecStartPre=</varname>
363 above. Use of this setting is
364 optional. All processes remaining for
365 a service after the commands
366 configured in this option are run are
367 terminated according to the
368 <varname>KillMode=</varname> setting
369 (see below). If this option is not
370 specified the process is terminated
371 right-away when service stop is
372 requested. Specifier and environment
373 variable substitution is supported
375 <literal>$MAINPID</literal>, see
376 above).</para></listitem>
380 <term><varname>ExecStopPost=</varname></term>
381 <listitem><para>Additional commands
382 that are executed after the service
383 was stopped using the commands
385 <varname>ExecStop=</varname>. This
386 argument takes multiple command lines,
387 following the same scheme as pointed
389 <varname>ExecStartPre</varname>. Use
391 optional. Specifier and environment
392 variable substitution is
393 supported.</para></listitem>
397 <term><varname>RestartSec=</varname></term>
398 <listitem><para>Configures the time to
399 sleep before restarting a service (as
401 <varname>Restart=</varname>). Takes a
402 unit-less value in seconds, or a time
403 span value such as "5min
405 100ms.</para></listitem>
409 <term><varname>TimeoutSec=</varname></term>
410 <listitem><para>Configures the time to
411 wait for start-up and stop. If a
412 daemon service does not signal
413 start-up completion within the
414 configured time the service will be
415 considered failed and be shut down
416 again. If a service is asked to stop
417 but does not terminate in the
418 specified time it will be terminated
419 forcibly via SIGTERM, and after
420 another delay of this time with
422 <varname>KillMode=</varname>
423 below.) Takes a unit-less value in seconds, or a
424 time span value such as "5min
425 20s". Pass 0 to disable the timeout
427 60s.</para></listitem>
431 <term><varname>Restart=</varname></term>
432 <listitem><para>Configures whether the
433 main service process shall be
434 restarted when it exits. Takes one of
436 <option>on-success</option>,
437 <option>on-failure</option>,
438 <option>on-abort</option> or
439 <option>always</option>. If set to
440 <option>no</option> (the default) the
441 service will not be restarted when it
443 <option>on-success</option> it will be
444 restarted only when it exited cleanly,
445 i.e. terminated with an exit code of
447 <option>on-failure</option> it will be
448 restarted only when it exited with an
449 exit code not equalling 0, or when
450 terminated by a signal. If set to
451 <option>on-abort</option> it will be
452 restarted only if it exits due to
453 reception of an uncaught signal. If
454 set to <option>always</option> the
455 service will be restarted regardless
456 whether it exited cleanly or not, or
457 got terminated abnormally by a
458 signal.</para></listitem>
462 <term><varname>PermissionsStartOnly=</varname></term>
463 <listitem><para>Takes a boolean
464 argument. If true, the permission
465 related execution options as
467 <varname>User=</varname> and similar
469 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
470 for more information) are only applied
471 to the process started with
472 <varname>ExecStart=</varname>, and not
474 <varname>ExecStartPre=</varname>,
475 <varname>ExecStartPost=</varname>,
476 <varname>ExecReload=</varname>,
477 <varname>ExecStop=</varname>,
478 <varname>ExecStopPost=</varname>
479 commands. If false, the setting is
480 applied to all configured commands the
481 same way. Defaults to
482 false.</para></listitem>
486 <term><varname>RootDirectoryStartOnly=</varname></term>
487 <listitem><para>Takes a boolean
488 argument. If true, the root directory
489 as configured with the
490 <varname>RootDirectory=</varname>
492 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
493 for more information) is only applied
494 to the process started with
495 <varname>ExecStart=</varname>, and not
497 <varname>ExecStartPre=</varname>,
498 <varname>ExecStartPost=</varname>,
499 <varname>ExecReload=</varname>,
500 <varname>ExecStop=</varname>,
501 <varname>ExecStopPost=</varname>
502 commands. If false, the setting is
503 applied to all configured commands the
504 same way. Defaults to
505 false.</para></listitem>
509 <term><varname>SysVStartPriority=</varname></term>
510 <listitem><para>Set the SysV start
511 priority to use to order this service
512 in relation to SysV services lacking
513 LSB headers. This option is only
514 necessary to fix ordering in relation
515 to legacy SysV services, that have no
516 ordering information encoded in the
517 script headers. As such it should only
518 be used as temporary compatibility
519 option, and not be used in new unit
520 files. Almost always it is a better
521 choice to add explicit ordering
523 <varname>After=</varname> or
524 <varname>Before=</varname>,
525 instead. For more details see
526 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
527 used, pass an integer value in the
528 range 0-99.</para></listitem>
532 <term><varname>KillMode=</varname></term>
533 <listitem><para>Specifies how
534 processes of this service shall be
536 <option>control-group</option>,
537 <option>process-group</option>,
538 <option>process</option>,
539 <option>none</option>.</para>
542 <option>control-group</option> all
543 remaining processes in the control
544 group of this service will be
545 terminated on service stop, after the
546 stop command (as configured with
547 <varname>ExecStop=</varname>) is
549 <option>process-group</option> only
550 the members of the process group of
551 the main service process are
553 <option>process</option> only the main
554 process itself is killed. If set to
555 <option>none</option> no process is
556 killed. In this case only the stop
557 command will be executed on service
558 stop, but no process be killed
559 otherwise. Processes remaining alive
560 after stop are left in their control
561 group and the control group continues
562 to exist after stop unless it is
564 <option>control-group</option>.</para>
566 <para>Processes will first be
567 terminated via SIGTERM (unless the
568 signal to send is changed via
569 <varname>KillSignal=</varname>). If
570 then after a delay (configured via the
571 <varname>TimeoutSec=</varname> option)
572 processes still remain, the
573 termination request is repeated with
574 the SIGKILL signal (unless this is
576 <varname>SendSIGKILL=</varname>
578 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
580 information.</para></listitem>
584 <term><varname>KillSignal=</varname></term>
585 <listitem><para>Specifies which signal
586 to use when killing a
587 service. Defaults to SIGTERM.
592 <term><varname>SendSIGKILL=</varname></term>
593 <listitem><para>Specifies whether to
594 send SIGKILL to remaining processes
595 after a timeout, if the normal
596 shutdown procedure left processes of
597 the service around. Takes a boolean
598 value. Defaults to "yes".
603 <term><varname>NonBlocking=</varname></term>
604 <listitem><para>Set O_NONBLOCK flag
605 for all file descriptors passed via
606 socket-based activation. If true, all
607 file descriptors >= 3 (i.e. all except
608 STDIN/STDOUT/STDERR) will have
609 the O_NONBLOCK flag set and hence are in
610 non-blocking mode. This option is only
611 useful in conjunction with a socket
612 unit, as described in
613 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
614 to false.</para></listitem>
618 <term><varname>NotifyAccess=</varname></term>
619 <listitem><para>Controls access to the
620 service status notification socket, as
622 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
624 <option>none</option> (the default),
625 <option>main</option> or
626 <option>all</option>. If
627 <option>none</option> no daemon status
628 updates are accepted from the service
629 processes, all status update messages
630 are ignored. If <option>main</option>
631 only service updates sent from the
632 main process of the service are
633 accepted. If <option>all</option> all
634 services updates from all members of
635 the service's control group are
636 accepted. This option must be set to
637 open access to the notification socket
639 <varname>Type=notify</varname> (see above).</para></listitem>
643 <term><varname>Sockets=</varname></term>
644 <listitem><para>Specifies the name of
645 the socket units this service shall
646 inherit the sockets from when the
647 service (ignoring the different suffix
648 of course) is started. Normally it
649 should not be necessary to use this
650 setting as all sockets whose unit
651 shares the same name as the service
652 are passed to the spawned
655 <para>Note that the same socket may be
656 passed to multiple processes at the
657 same time. Also note that a different
658 service may be activated on incoming
659 traffic than inherits the sockets. Or
661 <varname>Service=</varname> setting of
662 <filename>.socket</filename> units
663 doesn't have to match the inverse of the
664 <varname>Sockets=</varname> setting of
665 the <filename>.service</filename> it
666 refers to.</para></listitem>
670 <term><varname>FsckPassNo=</varname></term>
671 <listitem><para>Set the fsck passno
672 priority to use to order this service
673 in relation to other file system
674 checking services. This option is only
675 necessary to fix ordering in relation
676 to fsck jobs automatically created for
677 all <filename>/etc/fstab</filename>
678 entries with a value in the fs_passno
679 column > 0. As such it should only be
680 used as option for fsck
681 services. Almost always it is a better
682 choice to add explicit ordering
684 <varname>After=</varname> or
685 <varname>Before=</varname>,
686 instead. For more details see
687 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
688 used, pass an integer value in the
690 <filename>/etc/fstab</filename>'s
691 fs_passno column. See
692 <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
693 for details.</para></listitem>
700 <title>See Also</title>
702 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
703 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
704 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
705 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>