chiark / gitweb /
service: allow services of Type=oneshot that specify no ExecStart= commands
[elogind.git] / man / systemd.service.xml
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2 <?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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9   Copyright 2010 Lennart Poettering
10
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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>Service unit configuration</refpurpose>
48         </refnamediv>
49
50         <refsynopsisdiv>
51                 <para><filename><replaceable>service</replaceable>.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, and in
76                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
77                 which define the way the processes of the service are
78                 terminated, and in
79                 <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
80                 which configure resource control settings for the
81                 processes of the service.</para>
82
83                 <para>Unless <varname>DefaultDependencies=</varname>
84                 is set to <option>false</option>, service units will
85                 implicitly have dependencies of type
86                 <varname>Requires=</varname> and
87                 <varname>After=</varname> on
88                 <filename>basic.target</filename> as well as
89                 dependencies of type <varname>Conflicts=</varname> and
90                 <varname>Before=</varname> on
91                 <filename>shutdown.target</filename>. These ensure
92                 that normal service units pull in basic system
93                 initialization, and are terminated cleanly prior to
94                 system shutdown. Only services involved with early
95                 boot or late system shutdown should disable this
96                 option.</para>
97
98                 <para>If a service is requested under a certain name
99                 but no unit configuration file is found, systemd looks
100                 for a SysV init script by the same name (with the
101                 <filename>.service</filename> suffix removed) and
102                 dynamically creates a service unit from that
103                 script. This is useful for compatibility with
104                 SysV. Note that this compatibility is quite
105                 comprehensive but not 100%. For details about the
106                 incompatibilities, see the <ulink
107                 url="http://www.freedesktop.org/wiki/Software/systemd/Incompatibilities">Incompatibilities
108                 with SysV</ulink> document.
109                 </para>
110         </refsect1>
111
112         <refsect1>
113                 <title>Options</title>
114
115                 <para>Service files must include a
116                 <literal>[Service]</literal> section, which carries
117                 information about the service and the process it
118                 supervises. A number of options that may be used in
119                 this section are shared with other unit types. These
120                 options are documented in
121                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
122                 and
123                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
124                 options specific to the <literal>[Service]</literal>
125                 section of service units are the following:</para>
126
127                 <variablelist class='unit-directives'>
128                         <varlistentry>
129                                 <term><varname>Type=</varname></term>
130
131                                 <listitem><para>Configures the process
132                                 start-up type for this service
133                                 unit. One of <option>simple</option>,
134                                 <option>forking</option>,
135                                 <option>oneshot</option>,
136                                 <option>dbus</option>,
137                                 <option>notify</option> or
138                                 <option>idle</option>.</para>
139
140                                 <para>If set to
141                                 <option>simple</option> (the default
142                                 if neither
143                                 <varname>Type=</varname> nor
144                                 <varname>BusName=</varname>, but
145                                 <varname>ExecStart=</varname> are
146                                 specified), it is expected that the
147                                 process configured with
148                                 <varname>ExecStart=</varname> is the
149                                 main process of the service. In this
150                                 mode, if the process offers
151                                 functionality to other processes on
152                                 the system, its communication channels
153                                 should be installed before the daemon
154                                 is started up (e.g. sockets set up by
155                                 systemd, via socket activation), as
156                                 systemd will immediately proceed
157                                 starting follow-up units.</para>
158
159                                 <para>If set to
160                                 <option>forking</option>, it is
161                                 expected that the process configured
162                                 with <varname>ExecStart=</varname>
163                                 will call <function>fork()</function>
164                                 as part of its start-up. The parent process is
165                                 expected to exit when start-up is
166                                 complete and all communication
167                                 channels are set up. The child continues
168                                 to run as the main daemon
169                                 process. This is the behavior of
170                                 traditional UNIX daemons. If this
171                                 setting is used, it is recommended to
172                                 also use the
173                                 <varname>PIDFile=</varname> option, so
174                                 that systemd can identify the main
175                                 process of the daemon. systemd will
176                                 proceed with starting follow-up units
177                                 as soon as the parent process
178                                 exits.</para>
179
180                                 <para>Behavior of
181                                 <option>oneshot</option> is similar to
182                                 <option>simple</option>; however, it
183                                 is expected that the process has to
184                                 exit before systemd starts follow-up
185                                 units. <varname>RemainAfterExit=</varname>
186                                 is particularly useful for this type
187                                 of service. This is the implied
188                                 default if neither
189                                 <varname>Type=</varname> or
190                                 <varname>ExecStart=</varname> are
191                                 specified.</para>
192
193                                 <para>Behavior of
194                                 <option>dbus</option> is similar to
195                                 <option>simple</option>; however, it is
196                                 expected that the daemon acquires a
197                                 name on the D-Bus bus, as configured
198                                 by
199                                 <varname>BusName=</varname>. systemd
200                                 will proceed with starting follow-up
201                                 units after the D-Bus bus name has been
202                                 acquired. Service units with this
203                                 option configured implicitly gain
204                                 dependencies on the
205                                 <filename>dbus.socket</filename>
206                                 unit. This type is the default if
207                                 <varname>BusName=</varname> is
208                                 specified.</para>
209
210                                 <para>Behavior of
211                                 <option>notify</option> is similar to
212                                 <option>simple</option>; however, it is
213                                 expected that the daemon sends a
214                                 notification message via
215                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
216                                 or an equivalent call when it has finished
217                                 starting up. systemd will proceed with
218                                 starting follow-up units after this
219                                 notification message has been sent. If
220                                 this option is used,
221                                 <varname>NotifyAccess=</varname> (see
222                                 below) should be set to open access to
223                                 the notification socket provided by
224                                 systemd. If
225                                 <varname>NotifyAccess=</varname> is
226                                 not set, it will be implicitly set to
227                                 <option>main</option>. Note that
228                                 currently
229                                 <varname>Type=</varname><option>notify</option>
230                                 will not work if used in combination with
231                                 <varname>PrivateNetwork=</varname><option>yes</option>.</para>
232
233                                 <para>Behavior of
234                                 <option>idle</option> is very similar
235                                 to <option>simple</option>; however,
236                                 actual execution of the service
237                                 binary is delayed until all jobs are
238                                 dispatched. This may be used to avoid
239                                 interleaving of output of shell
240                                 services with the status output on the
241                                 console.</para>
242                                 </listitem>
243                         </varlistentry>
244
245                         <varlistentry>
246                                 <term><varname>RemainAfterExit=</varname></term>
247
248                                 <listitem><para>Takes a boolean value
249                                 that specifies whether the service
250                                 shall be considered active even when
251                                 all its processes exited. Defaults to
252                                 <option>no</option>.</para>
253                                 </listitem>
254                         </varlistentry>
255
256                         <varlistentry>
257                                 <term><varname>GuessMainPID=</varname></term>
258
259                                 <listitem><para>Takes a boolean value
260                                 that specifies whether systemd should
261                                 try to guess the main PID of a service
262                                 if it cannot be determined
263                                 reliably. This option is ignored
264                                 unless <option>Type=forking</option>
265                                 is set and <option>PIDFile=</option>
266                                 is unset because for the other types
267                                 or with an explicitly configured PID
268                                 file, the main PID is always known. The
269                                 guessing algorithm might come to
270                                 incorrect conclusions if a daemon
271                                 consists of more than one process. If
272                                 the main PID cannot be determined,
273                                 failure detection and automatic
274                                 restarting of a service will not work
275                                 reliably. Defaults to
276                                 <option>yes</option>.</para>
277                                 </listitem>
278                         </varlistentry>
279
280                         <varlistentry>
281                                 <term><varname>PIDFile=</varname></term>
282
283                                 <listitem><para>Takes an absolute file
284                                 name pointing to the PID file of this
285                                 daemon. Use of this option is
286                                 recommended for services where
287                                 <varname>Type=</varname> is set to
288                                 <option>forking</option>. systemd will
289                                 read the PID of the main process of
290                                 the daemon after start-up of the
291                                 service. systemd will not write to the
292                                 file configured here.</para>
293                                 </listitem>
294                         </varlistentry>
295
296                         <varlistentry>
297                                 <term><varname>BusName=</varname></term>
298
299                                 <listitem><para>Takes a D-Bus bus
300                                 name that this service is reachable
301                                 as. This option is mandatory for
302                                 services where
303                                 <varname>Type=</varname> is set to
304                                 <option>dbus</option>, but its use
305                                 is otherwise recommended if the process
306                                 takes a name on the D-Bus bus.</para>
307                                 </listitem>
308                         </varlistentry>
309
310                         <varlistentry>
311                                 <term><varname>ExecStart=</varname></term>
312                                 <listitem><para>Commands with their
313                                 arguments that are executed when this
314                                 service is started. For each of the
315                                 specified commands, the first argument
316                                 must be an absolute and literal path
317                                 to an executable.</para>
318
319                                 <para>When <varname>Type</varname> is
320                                 not <option>oneshot</option>, only one
321                                 command may and must be given. When
322                                 <varname>Type=oneshot</varname> is
323                                 used, none or more than one command
324                                 may be specified. Multiple command
325                                 lines may be concatenated in a single
326                                 directive by separating them with
327                                 semicolons (these semicolons must be
328                                 passed as separate
329                                 words). Alternatively, this directive
330                                 may be specified more than once with
331                                 the same effect.  Lone semicolons may
332                                 be escaped as
333                                 <literal>\;</literal>. If the empty
334                                 string is assigned to this option, the
335                                 list of commands to start is reset,
336                                 prior assignments of this option will
337                                 have no effect. If no
338                                 <varname>ExecStart=</varname> is
339                                 specified, then the service must have
340                                 <varname>RemainAfterExit=yes</varname>
341                                 set.</para>
342
343                                 <para>Each command line is split on
344                                 whitespace, with the first item being
345                                 the command to execute, and the
346                                 subsequent items being the arguments.
347                                 Double quotes ("...") and single
348                                 quotes ('...') may be used, in which
349                                 case everything until the next
350                                 matching quote becomes part of the
351                                 same argument. Quotes themselves are
352                                 removed after parsing. In addition, a
353                                 trailing backslash
354                                 (<literal>\</literal>) may be used to
355                                 merge lines. This syntax is intended
356                                 to be very similar to shell syntax,
357                                 but only the meta-characters and
358                                 expansions described in the following
359                                 paragraphs are understood.
360                                 Specifically, redirection using
361                                 <literal>&lt;</literal>,
362                                 <literal>&lt;&lt;</literal>,
363                                 <literal>&gt;</literal>, and
364                                 <literal>&gt;&gt;</literal>, pipes
365                                 using <literal>|</literal>, and
366                                 running programs in the background
367                                 using <literal>&amp;</literal>
368                                 and <emphasis>other elements of shell
369                                 syntax are not supported</emphasis>.
370                                 </para>
371
372                                 <para>If more than one command is
373                                 specified, the commands are invoked
374                                 sequentially in the order they appear
375                                 in the unit file. If one of the
376                                 commands fails (and is not prefixed
377                                 with <literal>-</literal>), other lines
378                                 are not executed, and the unit is
379                                 considered failed.</para>
380
381                                 <para>Unless
382                                 <varname>Type=forking</varname> is
383                                 set, the process started via this
384                                 command line will be considered the
385                                 main process of the daemon.</para>
386
387                                 <para>The command line accepts
388                                 <literal>%</literal> specifiers as
389                                 described in
390                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
391                                 Note that the first argument of the
392                                 command line (i.e. the program to
393                                 execute) may not include
394                                 specifiers.</para>
395
396                                 <para>Basic environment variable
397                                 substitution is supported. Use
398                                 <literal>${FOO}</literal> as part of a
399                                 word, or as a word of its own, on the
400                                 command line, in which case it will be
401                                 replaced by the value of the
402                                 environment variable including all
403                                 whitespace it contains, resulting in a
404                                 single argument. Use
405                                 <literal>$FOO</literal> as a separate
406                                 word on the command line, in which
407                                 case it will be replaced by the value
408                                 of the environment variable split at
409                                 whitespace, resulting in zero or more
410                                 arguments. To pass a literal dollar
411                                 sign, use <literal>$$</literal>.
412                                 Variables whose value is not known at
413                                 expansion time are treated as empty
414                                 strings. Note that the first argument
415                                 (i.e. the program to execute) may not
416                                 be a variable.</para>
417
418                                 <para>Variables to be used in this
419                                 fashion may be defined through
420                                 <varname>Environment=</varname> and
421                                 <varname>EnvironmentFile=</varname>.
422                                 In addition, variables listed in the
423                                 section "Environment variables in
424                                 spawned processes" in
425                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
426                                 which are considered "static
427                                 configuration", may be used (this includes
428                                 e.g. <varname>$USER</varname>, but not
429                                 <varname>$TERM</varname>).</para>
430
431                                 <para>Optionally, if the absolute file
432                                 name is prefixed with
433                                 <literal>@</literal>, the second token
434                                 will be passed as
435                                 <literal>argv[0]</literal> to the
436                                 executed process, followed by the
437                                 further arguments specified. If the
438                                 absolute filename is prefixed with
439                                 <literal>-</literal>, an exit code of
440                                 the command normally considered a
441                                 failure (i.e. non-zero exit status or
442                                 abnormal exit due to signal) is ignored
443                                 and considered success. If both
444                                 <literal>-</literal> and
445                                 <literal>@</literal> are used, they
446                                 can appear in either order.</para>
447
448                                 <para>Note that this setting does not
449                                 directly support shell command
450                                 lines. If shell command lines are to
451                                 be used, they need to be passed
452                                 explicitly to a shell implementation
453                                 of some kind. Example:</para>
454                                 <programlisting>ExecStart=/bin/sh -c 'dmesg | tac'</programlisting>
455                                 <para>Example:</para>
456                                 <programlisting>ExecStart=/bin/echo one ; /bin/echo "two two"</programlisting>
457                                 <para>This will execute
458                                 <command>/bin/echo</command> two
459                                 times, each time with one argument:
460                                 <literal>one</literal> and
461                                 <literal>two two</literal>,
462                                 respectively. Because two commands are
463                                 specified,
464                                 <varname>Type=oneshot</varname> must
465                                 be used.</para>
466
467                                 <para>Example:</para>
468                                 <programlisting>ExecStart=/bin/echo / &gt;/dev/null &amp; \; \
469 /bin/ls</programlisting>
470                                 <para>This will execute
471                                 <command>/bin/echo</command> with five
472                                 arguments: <literal>/</literal>,
473                                 <literal>&gt;/dev/null</literal>,
474                                 <literal>&amp;</literal>,
475                                 <literal>;</literal>, and
476                                 <literal>/bin/ls</literal>.</para>
477
478                                 <para>Example:</para>
479                                 <programlisting>Environment="ONE=one" 'TWO=two two'
480 ExecStart=/bin/echo $ONE $TWO ${TWO}</programlisting>
481                                 <para>This will execute
482                                 <command>/bin/echo</command> with four
483                                 arguments: <literal>one</literal>,
484                                 <literal>two</literal>,
485                                 <literal>two</literal>, and
486                                 <literal>two two</literal>.</para>
487                               </listitem>
488                         </varlistentry>
489
490                         <varlistentry>
491                                 <term><varname>ExecStartPre=</varname></term>
492                                 <term><varname>ExecStartPost=</varname></term>
493                                 <listitem><para>Additional commands
494                                 that are executed before or after
495                                 the command in
496                                 <varname>ExecStart=</varname>, respectively.
497                                 Syntax is the same as for
498                                 <varname>ExecStart=</varname>, except
499                                 that multiple command lines are allowed
500                                 and the commands are executed one
501                                 after the other, serially.</para>
502
503                                 <para>If any of those commands (not
504                                 prefixed with <literal>-</literal>)
505                                 fail, the rest are not executed and
506                                 the unit is considered failed.</para>
507                                 </listitem>
508                         </varlistentry>
509
510                         <varlistentry>
511                                 <term><varname>ExecReload=</varname></term>
512                                 <listitem><para>Commands to execute to
513                                 trigger a configuration reload in the
514                                 service. This argument takes multiple
515                                 command lines, following the same
516                                 scheme as described for
517                                 <varname>ExecStart=</varname>
518                                 above. Use of this setting is
519                                 optional. Specifier and environment
520                                 variable substitution is supported
521                                 here following the same scheme as for
522                                 <varname>ExecStart=</varname>.</para>
523
524                                 <para>One additional, special
525                                 environment variable is set: if known,
526                                 <varname>$MAINPID</varname> is set to
527                                 the main process of the daemon, and
528                                 may be used for command lines like the
529                                 following:</para>
530
531                                 <programlisting>/bin/kill -HUP $MAINPID</programlisting>
532
533                                 <para>Note however that reloading a
534                                 daemon by sending a signal (as with
535                                 the example line above) is usually not
536                                 a good choice, because this is an
537                                 asynchronous operation and hence not
538                                 suitable to order reloads of multiple
539                                 services against each other. It is
540                                 strongly recommended to set
541                                 <varname>ExecReload=</varname> to a
542                                 command that not only triggers a
543                                 configuration reload of the daemon,
544                                 but also synchronously waits for it to
545                                 complete.</para>
546                                 </listitem>
547                         </varlistentry>
548
549                         <varlistentry>
550                                 <term><varname>ExecStop=</varname></term>
551                                 <listitem><para>Commands to execute to
552                                 stop the service started via
553                                 <varname>ExecStart=</varname>. This
554                                 argument takes multiple command lines,
555                                 following the same scheme as described
556                                 for <varname>ExecStart=</varname>
557                                 above. Use of this setting is
558                                 optional. After the commands configured
559                                 in this option are run, all processes
560                                 remaining for a service are
561                                 terminated according to the
562                                 <varname>KillMode=</varname> setting
563                                 (see
564                                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>). If
565                                 this option is not specified, the
566                                 process is terminated immediately when
567                                 service stop is requested. Specifier
568                                 and environment variable substitution
569                                 is supported (including
570                                 <varname>$MAINPID</varname>, see
571                                 above).</para></listitem>
572                         </varlistentry>
573
574                         <varlistentry>
575                                 <term><varname>ExecStopPost=</varname></term>
576                                 <listitem><para>Additional commands
577                                 that are executed after the service
578                                 was stopped. This includes cases where
579                                 the commands configured in
580                                 <varname>ExecStop=</varname> were used,
581                                 where the service does not have any
582                                 <varname>ExecStop=</varname> defined, or
583                                 where the service exited unexpectedly. This
584                                 argument takes multiple command lines,
585                                 following the same scheme as described
586                                 for <varname>ExecStart</varname>. Use
587                                 of these settings is
588                                 optional. Specifier and environment
589                                 variable substitution is
590                                 supported.</para></listitem>
591                         </varlistentry>
592
593                         <varlistentry>
594                                 <term><varname>RestartSec=</varname></term>
595                                 <listitem><para>Configures the time to
596                                 sleep before restarting a service (as
597                                 configured with
598                                 <varname>Restart=</varname>). Takes a
599                                 unit-less value in seconds, or a time
600                                 span value such as "5min
601                                 20s". Defaults to
602                                 100ms.</para></listitem>
603                         </varlistentry>
604
605                         <varlistentry>
606                                 <term><varname>TimeoutStartSec=</varname></term>
607                                 <listitem><para>Configures the time to
608                                 wait for start-up. If a
609                                 daemon service does not signal
610                                 start-up completion within the
611                                 configured time, the service will be
612                                 considered failed and will be shut
613                                 down again.
614                                 Takes a unit-less value in seconds, or a
615                                 time span value such as "5min
616                                 20s". Pass <literal>0</literal> to
617                                 disable the timeout logic. Defaults to
618                                 <varname>DefaultTimeoutStartSec=</varname> from
619                                 the manager configuration file, except
620                                 when <varname>Type=oneshot</varname> is
621                                 used, in which case the timeout
622                                 is disabled by default
623                                 (see <citerefentry><refentrytitle>systemd-systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
624                                 </para></listitem>
625                         </varlistentry>
626
627                         <varlistentry>
628                                 <term><varname>TimeoutStopSec=</varname></term>
629                                 <listitem><para>Configures the time to
630                                 wait for stop. If a service is asked
631                                 to stop, but does not terminate in the
632                                 specified time, it will be terminated
633                                 forcibly via <constant>SIGTERM</constant>,
634                                 and after another timeout of equal duration
635                                 with <constant>SIGKILL</constant> (see
636                                 <varname>KillMode=</varname>
637                                 in <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
638                                 Takes a unit-less value in seconds, or a
639                                 time span value such as "5min
640                                 20s". Pass <literal>0</literal> to disable
641                                 the timeout logic. Defaults to
642                                 <varname>DefaultTimeoutStopSec=</varname> from the
643                                 manager configuration file
644                                 (see <citerefentry><refentrytitle>systemd-systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
645                                 </para></listitem>
646                         </varlistentry>
647
648                         <varlistentry>
649                                 <term><varname>TimeoutSec=</varname></term>
650                                 <listitem><para>A shorthand for configuring
651                                 both <varname>TimeoutStartSec=</varname>
652                                 and <varname>TimeoutStopSec=</varname>
653                                 to the specified value.
654                                 </para></listitem>
655                         </varlistentry>
656
657                         <varlistentry>
658                                 <term><varname>WatchdogSec=</varname></term>
659                                 <listitem><para>Configures the
660                                 watchdog timeout for a service. The
661                                 watchdog is activated when the start-up is
662                                 completed. The service must call
663                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
664                                 regularly with <literal>WATCHDOG=1</literal>
665                                 (i.e. the "keep-alive ping"). If the time
666                                 between two such calls is larger than
667                                 the configured time, then the service
668                                 is placed in a failed state. By
669                                 setting <varname>Restart=</varname> to
670                                 <option>on-failure</option> or
671                                 <option>always</option>, the service
672                                 will be automatically restarted. The
673                                 time configured here will be passed to
674                                 the executed service process in the
675                                 <varname>WATCHDOG_USEC=</varname>
676                                 environment variable. This allows
677                                 daemons to automatically enable the
678                                 keep-alive pinging logic if watchdog
679                                 support is enabled for the service. If
680                                 this option is used,
681                                 <varname>NotifyAccess=</varname> (see
682                                 below) should be set to open access to
683                                 the notification socket provided by
684                                 systemd. If
685                                 <varname>NotifyAccess=</varname> is
686                                 not set, it will be implicitly set to
687                                 <option>main</option>. Defaults to 0,
688                                 which disables this
689                                 feature.</para></listitem>
690                         </varlistentry>
691
692                         <varlistentry>
693                                 <term><varname>Restart=</varname></term>
694                                 <listitem><para>Configures whether the
695                                 service shall be restarted when the
696                                 service process exits, is killed,
697                                 or a timeout is reached. The service
698                                 process may be the main service
699                                 process, but it may also be one of the
700                                 processes specified with
701                                 <varname>ExecStartPre=</varname>,
702                                 <varname>ExecStartPost=</varname>,
703                                 <varname>ExecStop=</varname>,
704                                 <varname>ExecStopPost=</varname>, or
705                                 <varname>ExecReload=</varname>.
706                                 When the death of the process is a
707                                 result of systemd operation (e.g. service
708                                 stop or restart), the service will not be
709                                 restarted. Timeouts include missing
710                                 the watchdog "keep-alive ping"
711                                 deadline and a service start, reload,
712                                 and stop operation timeouts.</para>
713
714                                 <para>Takes one of
715                                 <option>no</option>,
716                                 <option>on-success</option>,
717                                 <option>on-failure</option>,
718                                 <option>on-abnormal</option>,
719                                 <option>on-watchdog</option>,
720                                 <option>on-abort</option>, or
721                                 <option>always</option>. If set to
722                                 <option>no</option> (the default), the
723                                 service will not be restarted. If set
724                                 to <option>on-success</option>, it
725                                 will be restarted only when the
726                                 service process exits cleanly.  In
727                                 this context, a clean exit means an
728                                 exit code of 0, or one of the signals
729                                 <constant>SIGHUP</constant>,
730                                 <constant>SIGINT</constant>,
731                                 <constant>SIGTERM</constant> or
732                                 <constant>SIGPIPE</constant>, and
733                                 additionally, exit statuses and
734                                 signals specified in
735                                 <varname>SuccessExitStatus=</varname>.
736                                 If set to <option>on-failure</option>,
737                                 the service will be restarted when the
738                                 process exits with a non-zero exit
739                                 code, is terminated by a signal
740                                 (including on core dump, but excluding
741                                 the aforementiond four signals), when
742                                 an operation (such as service reload)
743                                 times out, and when the configured
744                                 watchdog timeout is triggered.  If set
745                                 to <option>on-abnormal</option>, the
746                                 service will be restarted when the
747                                 process is terminated by a signal
748                                 (including on core dump, excluding the
749                                 aforementioned four signals), when an
750                                 operation times out, or when the
751                                 watchdog timeout is triggered. If set
752                                 to <option>on-abort</option>, the
753                                 service will be restarted only if the
754                                 service process exits due to an
755                                 uncaught signal not specified as a
756                                 clean exit status.  If set to
757                                 <option>on-watchdog</option>, the
758                                 service will be restarted only if the
759                                 watchdog timeout for the service
760                                 expires.  If set to
761                                 <option>always</option>, the service
762                                 will be restarted regardless of
763                                 whether it exited cleanly or not, got
764                                 terminated abnormally by a signal, or
765                                 hit a timeout.</para>
766
767                                 <table>
768                                         <title>Exit causes and the effect of the <varname>Restart=</varname> settings on them</title>
769
770                                         <tgroup cols='2'>
771                                                 <colspec colname='path' />
772                                                 <colspec colname='expl' />
773                                                 <thead>
774                                                         <row>
775                                                                 <entry>Restart settings/Exit causes</entry>
776                                                                 <entry><option>no</option></entry>
777                                                                 <entry><option>always</option></entry>
778                                                                 <entry><option>on-success</option></entry>
779                                                                 <entry><option>on-failure</option></entry>
780                                                                 <entry><option>on-abnormal</option></entry>
781                                                                 <entry><option>on-abort</option></entry>
782                                                                 <entry><option>on-watchdog</option></entry>
783                                                         </row>
784                                                 </thead>
785                                                 <tbody>
786                                                         <row>
787                                                                 <entry>Clean exit code or signal</entry>
788                                                                 <entry/>
789                                                                 <entry>X</entry>
790                                                                 <entry>X</entry>
791                                                                 <entry/>
792                                                                 <entry/>
793                                                                 <entry/>
794                                                                 <entry/>
795                                                         </row>
796                                                         <row>
797                                                                 <entry>Unclean exit code</entry>
798                                                                 <entry/>
799                                                                 <entry>X</entry>
800                                                                 <entry/>
801                                                                 <entry>X</entry>
802                                                                 <entry/>
803                                                                 <entry/>
804                                                                 <entry/>
805                                                         </row>
806                                                         <row>
807                                                                 <entry>Unclean signal</entry>
808                                                                 <entry/>
809                                                                 <entry>X</entry>
810                                                                 <entry/>
811                                                                 <entry>X</entry>
812                                                                 <entry>X</entry>
813                                                                 <entry>X</entry>
814                                                                 <entry/>
815                                                         </row>
816                                                         <row>
817                                                                 <entry>Timeout</entry>
818                                                                 <entry/>
819                                                                 <entry>X</entry>
820                                                                 <entry/>
821                                                                 <entry>X</entry>
822                                                                 <entry>X</entry>
823                                                                 <entry/>
824                                                                 <entry/>
825                                                         </row>
826                                                         <row>
827                                                                 <entry>Watchdog</entry>
828                                                                 <entry/>
829                                                                 <entry>X</entry>
830                                                                 <entry/>
831                                                                 <entry>X</entry>
832                                                                 <entry>X</entry>
833                                                                 <entry/>
834                                                                 <entry>X</entry>
835                                                         </row>
836                                                 </tbody>
837                                         </tgroup>
838                                 </table>
839
840                                 <para>As exceptions to the setting
841                                 above the service will not be
842                                 restarted if the exit code or signal
843                                 is specified in
844                                 <varname>RestartPreventExitStatus=</varname>
845                                 (see below). Also, the services will
846                                 always be restarted if the exit code
847                                 or signal is specified in
848                                 <varname>RestartForceExitStatus=</varname>
849                                 (see below).</para>
850
851                                 <para>Setting this to
852                                 <option>on-failure</option> is the
853                                 recommended choice for long-running
854                                 services, in order to increase
855                                 reliability by attempting automatic
856                                 recovery from errors. For services
857                                 that shall be able to terminate on
858                                 their own choice (and avoid
859                                 immediate restarting),
860                                 <option>on-abnormal</option> is an
861                                 alternative choice.</para>
862                                 </listitem>
863                         </varlistentry>
864
865                         <varlistentry>
866                                 <term><varname>SuccessExitStatus=</varname></term>
867                                 <listitem><para>Takes a list of exit
868                                 status definitions that when returned
869                                 by the main service process will be
870                                 considered successful termination, in
871                                 addition to the normal successful exit
872                                 code 0 and the signals <constant>SIGHUP</constant>, <constant>SIGINT</constant>,
873                                 <constant>SIGTERM</constant>, and <constant>SIGPIPE</constant>. Exit status
874                                 definitions can either be numeric exit
875                                 codes or termination signal names,
876                                 separated by spaces. For example:
877                                 <programlisting>SuccessExitStatus=1 2 8 SIGKILL</programlisting>
878                                 ensures that exit codes 1, 2, 8 and
879                                 the termination signal
880                                 <constant>SIGKILL</constant> are
881                                 considered clean service terminations.
882                                 </para>
883
884                                 <para>Note that if a process has a
885                                 signal handler installed and exits by
886                                 calling
887                                 <citerefentry><refentrytitle>_exit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
888                                 in response to a signal, the
889                                 information about the signal is lost.
890                                 Programs should instead perform cleanup and kill themselves with the same signal instead. See
891                                 <ulink url="http://www.cons.org/cracauer/sigint.html">Proper handling of SIGINT/SIGQUIT — How to be a proper program</ulink>.</para>
892
893                                 <para>This option may appear more than once,
894                                 in which case the list of successful
895                                 exit statuses is merged. If the empty
896                                 string is assigned to this option, the
897                                 list is reset, all prior assignments
898                                 of this option will have no
899                                 effect.</para></listitem>
900                         </varlistentry>
901
902                         <varlistentry>
903                                 <term><varname>RestartPreventExitStatus=</varname></term>
904                                 <listitem><para>Takes a list of exit
905                                 status definitions that when returned
906                                 by the main service process will
907                                 prevent automatic service restarts,
908                                 regardless of the restart setting
909                                 configured with
910                                 <varname>Restart=</varname>. Exit
911                                 status definitions can either be
912                                 numeric exit codes or termination
913                                 signal names, and are separated by
914                                 spaces. Defaults to the empty list, so
915                                 that, by default, no exit status is
916                                 excluded from the configured restart
917                                 logic. For example:
918                                 <programlisting>RestartPreventExitStatus=1 6 SIGABRT</programlisting> ensures that exit
919                                 codes 1 and 6 and the termination
920                                 signal <constant>SIGABRT</constant> will
921                                 not result in automatic service
922                                 restarting. This
923                                 option may appear more than once, in
924                                 which case the list of restart-preventing
925                                 statuses is merged. If the empty
926                                 string is assigned to this option, the
927                                 list is reset and all prior assignments
928                                 of this option will have no
929                                 effect.</para></listitem>
930                         </varlistentry>
931
932                         <varlistentry>
933                                 <term><varname>RestartForceExitStatus=</varname></term>
934                                 <listitem><para>Takes a list of exit
935                                 status definitions that when returned
936                                 by the main service process will force
937                                 automatic service restarts, regardless
938                                 of the restart setting configured with
939                                 <varname>Restart=</varname>. The
940                                 argument format is similar to
941                                 <varname>RestartPreventExitStatus=</varname>.</para></listitem>
942                         </varlistentry>
943
944                         <varlistentry>
945                                 <term><varname>PermissionsStartOnly=</varname></term>
946                                 <listitem><para>Takes a boolean
947                                 argument. If true, the permission-related
948                                 execution options, as
949                                 configured with
950                                 <varname>User=</varname> and similar
951                                 options (see
952                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
953                                 for more information), are only applied
954                                 to the process started with
955                                 <varname>ExecStart=</varname>, and not
956                                 to the various other
957                                 <varname>ExecStartPre=</varname>,
958                                 <varname>ExecStartPost=</varname>,
959                                 <varname>ExecReload=</varname>,
960                                 <varname>ExecStop=</varname>, and
961                                 <varname>ExecStopPost=</varname>
962                                 commands. If false, the setting is
963                                 applied to all configured commands the
964                                 same way. Defaults to
965                                 false.</para></listitem>
966                         </varlistentry>
967
968                         <varlistentry>
969                                 <term><varname>RootDirectoryStartOnly=</varname></term>
970                                 <listitem><para>Takes a boolean
971                                 argument. If true, the root directory,
972                                 as configured with the
973                                 <varname>RootDirectory=</varname>
974                                 option (see
975                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
976                                 for more information), is only applied
977                                 to the process started with
978                                 <varname>ExecStart=</varname>, and not
979                                 to the various other
980                                 <varname>ExecStartPre=</varname>,
981                                 <varname>ExecStartPost=</varname>,
982                                 <varname>ExecReload=</varname>,
983                                 <varname>ExecStop=</varname>, and
984                                 <varname>ExecStopPost=</varname>
985                                 commands. If false, the setting is
986                                 applied to all configured commands the
987                                 same way. Defaults to
988                                 false.</para></listitem>
989                         </varlistentry>
990
991                         <varlistentry>
992                                 <term><varname>NonBlocking=</varname></term>
993                                 <listitem><para>Set the
994                                 <constant>O_NONBLOCK</constant> flag
995                                 for all file descriptors passed via
996                                 socket-based activation. If true, all
997                                 file descriptors >= 3 (i.e. all except
998                                 stdin, stdout, and stderr) will have
999                                 the <constant>O_NONBLOCK</constant> flag
1000                                 set and hence are in
1001                                 non-blocking mode. This option is only
1002                                 useful in conjunction with a socket
1003                                 unit, as described in
1004                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
1005                                 to false.</para></listitem>
1006                         </varlistentry>
1007
1008                         <varlistentry>
1009                                 <term><varname>NotifyAccess=</varname></term>
1010                                 <listitem><para>Controls access to the
1011                                 service status notification socket, as
1012                                 accessible via the
1013                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
1014                                 call. Takes one of
1015                                 <option>none</option> (the default),
1016                                 <option>main</option> or
1017                                 <option>all</option>. If
1018                                 <option>none</option>, no daemon status
1019                                 updates are accepted from the service
1020                                 processes, all status update messages
1021                                 are ignored. If <option>main</option>,
1022                                 only service updates sent from the
1023                                 main process of the service are
1024                                 accepted. If <option>all</option>, all
1025                                 services updates from all members of
1026                                 the service's control group are
1027                                 accepted. This option should be set to
1028                                 open access to the notification socket
1029                                 when using
1030                                 <varname>Type=notify</varname> or
1031                                 <varname>WatchdogSec=</varname> (see
1032                                 above). If those options are used but
1033                                 <varname>NotifyAccess=</varname> is not
1034                                 configured, it will be implicitly set
1035                                 to
1036                                 <option>main</option>.</para></listitem>
1037                         </varlistentry>
1038
1039                         <varlistentry>
1040                                 <term><varname>Sockets=</varname></term>
1041                                 <listitem><para>Specifies the name of
1042                                 the socket units this service shall
1043                                 inherit the sockets from when the
1044                                 service is started. Normally it
1045                                 should not be necessary to use this
1046                                 setting as all sockets whose unit
1047                                 shares the same name as the service
1048                                 (ignoring the different suffix of course)
1049                                 are passed to the spawned
1050                                 process.</para>
1051
1052                                 <para>Note that the same socket may be
1053                                 passed to multiple processes at the
1054                                 same time. Also note that a different
1055                                 service may be activated on incoming
1056                                 traffic than that which inherits the
1057                                 sockets. Or in other words: the
1058                                 <varname>Service=</varname> setting of
1059                                 <filename>.socket</filename> units
1060                                 does not have to match the inverse of
1061                                 the <varname>Sockets=</varname>
1062                                 setting of the
1063                                 <filename>.service</filename> it
1064                                 refers to.</para>
1065
1066                                 <para>This option may appear more than
1067                                 once, in which case the list of socket
1068                                 units is merged. If the empty string
1069                                 is assigned to this option, the list of
1070                                 sockets is reset, and all prior uses of
1071                                 this setting will have no
1072                                 effect.</para></listitem>
1073                         </varlistentry>
1074
1075                         <varlistentry>
1076                                 <term><varname>StartLimitInterval=</varname></term>
1077                                 <term><varname>StartLimitBurst=</varname></term>
1078
1079                                 <listitem><para>Configure service
1080                                 start rate limiting. By default,
1081                                 services which are started more
1082                                 than 5 times within 10 seconds are not
1083                                 permitted to start any more times
1084                                 until the 10 second interval ends. With
1085                                 these two options, this rate limiting
1086                                 may be modified. Use
1087                                 <varname>StartLimitInterval=</varname>
1088                                 to configure the checking interval (defaults to
1089                                 <varname>DefaultStartLimitInterval=</varname> in
1090                                 manager configuration file, set to 0 to disable
1091                                 any kind of rate limiting). Use
1092                                 <varname>StartLimitBurst=</varname> to
1093                                 configure how many starts per interval
1094                                 are allowed (defaults to
1095                                 <varname>DefaultStartLimitBurst=</varname> in
1096                                 manager configuration file). These
1097                                 configuration options are particularly
1098                                 useful in conjunction with
1099                                 <varname>Restart=</varname>; however,
1100                                 they apply to all kinds of starts
1101                                 (including manual), not just those
1102                                 triggered by the
1103                                 <varname>Restart=</varname> logic.
1104                                 Note that units which are configured
1105                                 for <varname>Restart=</varname> and
1106                                 which reach the start limit are not
1107                                 attempted to be restarted anymore;
1108                                 however, they may still be restarted
1109                                 manually at a later point, from which
1110                                 point on, the restart logic is again
1111                                 activated. Note that
1112                                 <command>systemctl
1113                                 reset-failed</command> will cause the
1114                                 restart rate counter for a service to
1115                                 be flushed, which is useful if the
1116                                 administrator wants to manually start
1117                                 a service and the start limit
1118                                 interferes with
1119                                 that.</para></listitem>
1120                         </varlistentry>
1121
1122                         <varlistentry>
1123                                 <term><varname>StartLimitAction=</varname></term>
1124
1125                                 <listitem><para>Configure the action
1126                                 to take if the rate limit configured
1127                                 with
1128                                 <varname>StartLimitInterval=</varname>
1129                                 and
1130                                 <varname>StartLimitBurst=</varname> is
1131                                 hit. Takes one of
1132                                 <option>none</option>,
1133                                 <option>reboot</option>,
1134                                 <option>reboot-force</option>, or
1135                                 <option>reboot-immediate</option>. If
1136                                 <option>none</option> is set,
1137                                 hitting the rate limit will trigger no
1138                                 action besides that the start will not
1139                                 be permitted. <option>reboot</option>
1140                                 causes a reboot following the normal
1141                                 shutdown procedure (i.e. equivalent to
1142                                 <command>systemctl reboot</command>).
1143                                 <option>reboot-force</option> causes
1144                                 a forced reboot which will terminate
1145                                 all processes forcibly but should
1146                                 cause no dirty file systems on reboot
1147                                 (i.e. equivalent to <command>systemctl
1148                                 reboot -f</command>) and
1149                                 <option>reboot-immediate</option>
1150                                 causes immediate execution of the
1151                                 <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1152                                 system call, which might result in
1153                                 data loss. Defaults to
1154                                 <option>none</option>.</para></listitem>
1155                         </varlistentry>
1156
1157                         <varlistentry>
1158                                 <term><varname>RebootArgument=</varname></term>
1159                                 <listitem><para>Configure the optional
1160                                 argument for the
1161                                 <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1162                                 system call if
1163                                 <varname>StartLimitAction=</varname>
1164                                 is a reboot action. This works just
1165                                 like the optional argument to
1166                                 <command>systemctl reboot</command>
1167                                 command.</para></listitem>
1168                         </varlistentry>
1169
1170                         <varlistentry>
1171                                 <term><varname>FailureAction=</varname></term>
1172                                 <listitem><para>Configure the action
1173                                 to take when the service enters a failed
1174                                 state. Takes the same values as
1175                                 <varname>StartLimitAction=</varname>
1176                                 and executes the same actions.
1177                                 Defaults to <option>none</option>.
1178                                 </para></listitem>
1179                         </varlistentry>
1180
1181                 </variablelist>
1182
1183                 <para>Check
1184                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1185                 and
1186                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1187                 for more settings.</para>
1188
1189         </refsect1>
1190
1191         <refsect1>
1192                 <title>Compatibility Options</title>
1193
1194                 <para>The following options are also available in the
1195                 <literal>[Service]</literal> section, but exist purely
1196                 for compatibility reasons and should not be used in
1197                 newly written service files.</para>
1198
1199                 <variablelist class='unit-directives'>
1200                         <varlistentry>
1201                                 <term><varname>SysVStartPriority=</varname></term>
1202                                 <listitem><para>Set the SysV start
1203                                 priority to use to order this service
1204                                 in relation to SysV services lacking
1205                                 LSB headers. This option is only
1206                                 necessary to fix ordering in relation
1207                                 to legacy SysV services that have no
1208                                 ordering information encoded in the
1209                                 script headers. As such, it should only
1210                                 be used as a temporary compatibility
1211                                 option and should not be used in new unit
1212                                 files. Almost always, it is a better
1213                                 choice to add explicit ordering
1214                                 directives via
1215                                 <varname>After=</varname> or
1216                                 <varname>Before=</varname>,
1217                                 instead. For more details, see
1218                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1219                                 If used, pass an integer value in the
1220                                 range 0-99.</para></listitem>
1221                         </varlistentry>
1222                 </variablelist>
1223         </refsect1>
1224
1225         <refsect1>
1226                   <title>See Also</title>
1227                   <para>
1228                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1229                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1230                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1231                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1232                           <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1233                           <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1234                           <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1235                   </para>
1236         </refsect1>
1237
1238 </refentry>