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