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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
11   systemd is free software; you can redistribute it and/or modify it
12   under the terms of the GNU General Public License as published by
13   the Free Software Foundation; either version 2 of the License, or
14   (at your option) any later version.
15
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19   General Public License for more details.
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22   along with systemd; If not, see <http://www.gnu.org/licenses/>.
23 -->
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>systemd service configuration files</refpurpose>
48         </refnamediv>
49
50         <refsynopsisdiv>
51                 <para><filename>systemd.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.</para>
76
77                 <para>Unless <varname>DefaultDependencies=</varname>
78                 is set to <option>false</option>, service units will
79                 implicitly have dependencies of type
80                 <varname>Requires=</varname> and
81                 <varname>After=</varname> on
82                 <filename>basic.target</filename> as well as
83                 dependencies of type <varname>Conflicts=</varname> and
84                 <varname>Before=</varname> on
85                 <filename>shutdown.target</filename>. These ensure
86                 that normal service units pull in basic system
87                 initialization, and are terminated cleanly prior to
88                 system shutdown. Only services involved with early
89                 boot or late system shutdown should disable this
90                 option.</para>
91
92                 <para>If a service is requested under a certain name
93                 but no unit configuration file is found, systemd looks
94                 for a SysV init script by the same name (with the
95                 <filename>.service</filename> suffix removed) and
96                 dynamically creates a service unit from that
97                 script. This is useful for compatibility with
98                 SysV.</para>
99         </refsect1>
100
101         <refsect1>
102                 <title>Options</title>
103
104                 <para>Service files must include a
105                 <literal>[Service]</literal> section, which carries
106                 information about the service and the process it
107                 supervises. A number of options that may be used in
108                 this section are shared with other unit types. These
109                 options are documented in
110                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
111                 options specific to the <literal>[Service]</literal>
112                 section of service units are the following:</para>
113
114                 <variablelist>
115                         <varlistentry>
116                                 <term><varname>Type=</varname></term>
117
118                                 <listitem><para>Configures the process
119                                 start-up type for this service
120                                 unit. One of <option>simple</option>,
121                                 <option>forking</option>,
122                                 <option>oneshot</option>,
123                                 <option>dbus</option>,
124                                 <option>notify</option>.</para>
125
126                                 <para>If set to
127                                 <option>simple</option> (the default
128                                 value) it is expected that the process
129                                 configured with
130                                 <varname>ExecStart=</varname> is the
131                                 main process of the service. In this
132                                 mode, if the process offers
133                                 functionality to other processes on
134                                 the system its communication channels
135                                 should be installed before the daemon
136                                 is started up (e.g. sockets set up by
137                                 systemd, via socket activation), as
138                                 systemd will immediately proceed
139                                 starting follow-up units.</para>
140
141                                 <para>If set to
142                                 <option>forking</option> it is
143                                 expected that the process configured
144                                 with <varname>ExecStart=</varname>
145                                 will call <function>fork()</function>
146                                 as part of its start-up. The parent process is
147                                 expected to exit when start-up is
148                                 complete and all communication
149                                 channels set up. The child continues
150                                 to run as the main daemon
151                                 process. This is the behaviour of
152                                 traditional UNIX daemons. If this
153                                 setting is used, it is recommended to
154                                 also use the
155                                 <varname>PIDFile=</varname> option, so
156                                 that systemd can identify the main
157                                 process of the daemon. systemd will
158                                 proceed starting follow-up units as
159                                 soon as the parent process
160                                 exits.</para>
161
162                                 <para>Behaviour of
163                                 <option>oneshot</option> is similar
164                                 to <option>simple</option>, however
165                                 it is expected that the process has to
166                                 exit before systemd starts follow-up
167                                 units. <varname>RemainAfterExit=</varname>
168                                 is particularly useful for this type
169                                 of service.</para>
170
171                                 <para>Behaviour of
172                                 <option>dbus</option> is similar to
173                                 <option>simple</option>, however it is
174                                 expected that the daemon acquires a
175                                 name on the D-Bus bus, as configured
176                                 by
177                                 <varname>BusName=</varname>. systemd
178                                 will proceed starting follow-up units
179                                 after the D-Bus bus name has been
180                                 acquired. Service units with this
181                                 option configured implicitly gain
182                                 dependencies on the
183                                 <filename>dbus.socket</filename>
184                                 unit.</para>
185
186                                 <para>Behaviour of
187                                 <option>notify</option> is similar to
188                                 <option>simple</option>, however it is
189                                 expected that the daemon sends a
190                                 notification message via
191                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
192                                 or an equivalent call when it finished
193                                 starting up. systemd will proceed
194                                 starting follow-up units after this
195                                 notification message has been sent. If
196                                 this option is used
197                                 <varname>NotifyAccess=</varname> (see
198                                 below) should be set to open access to
199                                 the notification socket provided by
200                                 systemd. If
201                                 <varname>NotifyAccess=</varname> is not
202                                 set, it will implicitly be set to
203                                 <option>main</option>.</para>
204                                 </listitem>
205                         </varlistentry>
206
207                         <varlistentry>
208                                 <term><varname>RemainAfterExit=</varname></term>
209
210                                 <listitem><para>Takes a boolean value
211                                 that specifies whether the service
212                                 shall be considered active even when
213                                 all its processes exited. Defaults to
214                                 <option>no</option>.</para>
215                                 </listitem>
216                         </varlistentry>
217
218                         <varlistentry>
219                                 <term><varname>GuessMainPID=</varname></term>
220
221                                 <listitem><para>Takes a boolean value
222                                 that specifies whether systemd should
223                                 try to guess the main PID of a service
224                                 should if it cannot be determined
225                                 reliably. This option is ignored
226                                 unless <option>Type=forking</option>
227                                 is set and <option>PIDFile=</option>
228                                 is unset because for the other types
229                                 or with an explicitly configured PID
230                                 file the main PID is always known. The
231                                 guessing algorithm might come to
232                                 incorrect conclusions if a daemon
233                                 consists of more than one process. If
234                                 the main PID cannot be determined
235                                 failure detection and automatic
236                                 restarting of a service will not work
237                                 reliably. Defaults to
238                                 <option>yes</option>.</para>
239                                 </listitem>
240                         </varlistentry>
241
242                         <varlistentry>
243                                 <term><varname>PIDFile=</varname></term>
244
245                                 <listitem><para>Takes an absolute file
246                                 name pointing to the PID file of this
247                                 daemon. Use of this option is
248                                 recommended for services where
249                                 <varname>Type=</varname> is set to
250                                 <option>forking</option>. systemd will
251                                 read the PID of the main process of
252                                 the daemon after start-up of the
253                                 service. systemd will not write to the
254                                 file configured here.</para>
255                                 </listitem>
256                         </varlistentry>
257
258                         <varlistentry>
259                                 <term><varname>BusName=</varname></term>
260
261                                 <listitem><para>Takes a D-Bus bus
262                                 name, where this service is reachable
263                                 as. This option is mandatory for
264                                 services where
265                                 <varname>Type=</varname> is set to
266                                 <option>dbus</option>, but its use
267                                 is otherwise recommended as well if
268                                 the process takes a name on the D-Bus
269                                 bus.</para>
270                                 </listitem>
271                         </varlistentry>
272
273                         <varlistentry>
274                                 <term><varname>ExecStart=</varname></term>
275                                 <listitem><para>Takes a command line
276                                 that is executed when this service
277                                 shall be started up. The first token
278                                 of the command line must be an
279                                 absolute file name, then followed by
280                                 arguments for the process. It is
281                                 mandatory to set this option for all
282                                 services. This option may not be
283                                 specified more than once, except when
284                                 <varname>Type=oneshot</varname> is
285                                 used in which case more than one
286                                 <varname>ExecStart=</varname> line is
287                                 accepted which are then invoked one by
288                                 one, sequentially in the order they
289                                 appear in the unit file.</para>
290
291                                 <para>Optionally, if the absolute file
292                                 name is prefixed with
293                                 <literal>@</literal>, the second token
294                                 will be passed as
295                                 <literal>argv[0]</literal> to the
296                                 executed process, followed by the
297                                 further arguments specified. If the
298                                 first token is prefixed with
299                                 <literal>-</literal> an exit code of
300                                 the command normally considered a
301                                 failure (i.e. non-zero exit status or
302                                 abnormal exit due to signal) is ignored
303                                 and considered success. If both
304                                 <literal>-</literal> and
305                                 <literal>@</literal> are used for the
306                                 same command the former must precede
307                                 the latter. Unless
308                                 <varname>Type=forking</varname> is
309                                 set, the process started via this
310                                 command line will be considered the
311                                 main process of the daemon. The
312                                 command line accepts % specifiers as
313                                 described in
314                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
315
316                                 <para>On top of that basic environment
317                                 variable substitution is
318                                 supported. Use
319                                 <literal>${FOO}</literal> as part of a
320                                 word, or as word of its own on the
321                                 command line, in which case it will be
322                                 replaced by the value of the
323                                 environment variable including all
324                                 whitespace it contains, resulting in a
325                                 single argument.  Use
326                                 <literal>$FOO</literal> as a separate
327                                 word on the command line, in which
328                                 case it will be replaced by the value
329                                 of the environment variable split up
330                                 at whitespace, resulting in no or more
331                                 arguments. Note that the first
332                                 argument (i.e. the program to execute)
333                                 may not be a variable, and must be a
334                                 literal and absolute path
335                                 name.</para></listitem>
336                         </varlistentry>
337
338                         <varlistentry>
339                                 <term><varname>ExecStartPre=</varname></term>
340                                 <term><varname>ExecStartPost=</varname></term>
341                                 <listitem><para>Additional commands
342                                 that are executed before (resp. after)
343                                 the command in
344                                 <varname>ExecStart=</varname>. Multiple
345                                 command lines may be concatenated in a
346                                 single directive, by separating them
347                                 by semicolons (these semicolons must
348                                 be passed as separate words). In that
349                                 case, the commands are executed one
350                                 after the other,
351                                 serially. Alternatively, these
352                                 directives may be specified more than
353                                 once with the same effect. However,
354                                 the latter syntax is not recommended
355                                 for compatibility with parsers
356                                 suitable for XDG
357                                 <filename>.desktop</filename> files.
358                                 Use of these settings is
359                                 optional. Specifier and environment
360                                 variable substitution is
361                                 supported.</para></listitem>
362                         </varlistentry>
363
364                         <varlistentry>
365                                 <term><varname>ExecReload=</varname></term>
366                                 <listitem><para>Commands to execute to
367                                 trigger a configuration reload in the
368                                 service. This argument takes multiple
369                                 command lines, following the same
370                                 scheme as pointed out for
371                                 <varname>ExecStartPre=</varname>
372                                 above. Use of this setting is
373                                 optional. Specifier and environment
374                                 variable substitution is supported
375                                 here following the same scheme as for
376                                 <varname>ExecStart=</varname>. One
377                                 special environment variable is set:
378                                 if known <literal>$MAINPID</literal> is
379                                 set to the main process of the
380                                 daemon, and may be used for command
381                                 lines like the following:
382                                 <command>/bin/kill -HUP
383                                 $MAINPID</command>.</para></listitem>
384                         </varlistentry>
385
386                         <varlistentry>
387                                 <term><varname>ExecStop=</varname></term>
388                                 <listitem><para>Commands to execute to
389                                 stop the service started via
390                                 <varname>ExecStart=</varname>. This
391                                 argument takes multiple command lines,
392                                 following the same scheme as pointed
393                                 out for
394                                 <varname>ExecStartPre=</varname>
395                                 above. Use of this setting is
396                                 optional. All processes remaining for
397                                 a service after the commands
398                                 configured in this option are run are
399                                 terminated according to the
400                                 <varname>KillMode=</varname> setting
401                                 (see below). If this option is not
402                                 specified the process is terminated
403                                 right-away when service stop is
404                                 requested. Specifier and environment
405                                 variable substitution is supported
406                                 (including
407                                 <literal>$MAINPID</literal>, see
408                                 above).</para></listitem>
409                         </varlistentry>
410
411                         <varlistentry>
412                                 <term><varname>ExecStopPost=</varname></term>
413                                 <listitem><para>Additional commands
414                                 that are executed after the service
415                                 was stopped using the commands
416                                 configured in
417                                 <varname>ExecStop=</varname>. This
418                                 argument takes multiple command lines,
419                                 following the same scheme as pointed
420                                 out for
421                                 <varname>ExecStartPre</varname>. Use
422                                 of these settings is
423                                 optional. Specifier and environment
424                                 variable substitution is
425                                 supported.</para></listitem>
426                         </varlistentry>
427
428                         <varlistentry>
429                                 <term><varname>RestartSec=</varname></term>
430                                 <listitem><para>Configures the time to
431                                 sleep before restarting a service (as
432                                 configured with
433                                 <varname>Restart=</varname>). Takes a
434                                 unit-less value in seconds, or a time
435                                 span value such as "5min
436                                 20s". Defaults to
437                                 100ms.</para></listitem>
438                         </varlistentry>
439
440                         <varlistentry>
441                                 <term><varname>TimeoutSec=</varname></term>
442                                 <listitem><para>Configures the time to
443                                 wait for start-up and stop. If a
444                                 daemon service does not signal
445                                 start-up completion within the
446                                 configured time the service will be
447                                 considered failed and be shut down
448                                 again. If a service is asked to stop
449                                 but does not terminate in the
450                                 specified time it will be terminated
451                                 forcibly via SIGTERM, and after
452                                 another delay of this time with
453                                 SIGKILL. (See
454                                 <varname>KillMode=</varname>
455                                 below.) Takes a unit-less value in seconds, or a
456                                 time span value such as "5min
457                                 20s". Pass 0 to disable the timeout
458                                 logic. Defaults to
459                                 90s.</para></listitem>
460                         </varlistentry>
461
462                         <varlistentry>
463                                 <term><varname>Restart=</varname></term>
464                                 <listitem><para>Configures whether the
465                                 main service process shall be
466                                 restarted when it exits. Takes one of
467                                 <option>no</option>,
468                                 <option>on-success</option>,
469                                 <option>on-failure</option>,
470                                 <option>on-abort</option> or
471                                 <option>always</option>. If set to
472                                 <option>no</option> (the default) the
473                                 service will not be restarted when it
474                                 exits. If set to
475                                 <option>on-success</option> it will be
476                                 restarted only when it exited cleanly,
477                                 i.e. terminated with an exit code of
478                                 0. If set to
479                                 <option>on-failure</option> it will be
480                                 restarted only when it exited with an
481                                 exit code not equalling 0, or when
482                                 terminated by a signal. If set to
483                                 <option>on-abort</option> it will be
484                                 restarted only if it exits due to
485                                 reception of an uncaught signal. If
486                                 set to <option>always</option> the
487                                 service will be restarted regardless
488                                 whether it exited cleanly or not, or
489                                 got terminated abnormally by a
490                                 signal.</para></listitem>
491                         </varlistentry>
492
493                         <varlistentry>
494                                 <term><varname>PermissionsStartOnly=</varname></term>
495                                 <listitem><para>Takes a boolean
496                                 argument. If true, the permission
497                                 related execution options as
498                                 configured with
499                                 <varname>User=</varname> and similar
500                                 options (see
501                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
502                                 for more information) are only applied
503                                 to the process started with
504                                 <varname>ExecStart=</varname>, and not
505                                 to the various other
506                                 <varname>ExecStartPre=</varname>,
507                                 <varname>ExecStartPost=</varname>,
508                                 <varname>ExecReload=</varname>,
509                                 <varname>ExecStop=</varname>,
510                                 <varname>ExecStopPost=</varname>
511                                 commands. If false, the setting is
512                                 applied to all configured commands the
513                                 same way. Defaults to
514                                 false.</para></listitem>
515                         </varlistentry>
516
517                         <varlistentry>
518                                 <term><varname>RootDirectoryStartOnly=</varname></term>
519                                 <listitem><para>Takes a boolean
520                                 argument. If true, the root directory
521                                 as configured with the
522                                 <varname>RootDirectory=</varname>
523                                 option (see
524                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
525                                 for more information) is only applied
526                                 to the process started with
527                                 <varname>ExecStart=</varname>, and not
528                                 to the various other
529                                 <varname>ExecStartPre=</varname>,
530                                 <varname>ExecStartPost=</varname>,
531                                 <varname>ExecReload=</varname>,
532                                 <varname>ExecStop=</varname>,
533                                 <varname>ExecStopPost=</varname>
534                                 commands. If false, the setting is
535                                 applied to all configured commands the
536                                 same way. Defaults to
537                                 false.</para></listitem>
538                         </varlistentry>
539
540                         <varlistentry>
541                                 <term><varname>SysVStartPriority=</varname></term>
542                                 <listitem><para>Set the SysV start
543                                 priority to use to order this service
544                                 in relation to SysV services lacking
545                                 LSB headers. This option is only
546                                 necessary to fix ordering in relation
547                                 to legacy SysV services, that have no
548                                 ordering information encoded in the
549                                 script headers. As such it should only
550                                 be used as temporary compatibility
551                                 option, and not be used in new unit
552                                 files. Almost always it is a better
553                                 choice to add explicit ordering
554                                 directives via
555                                 <varname>After=</varname> or
556                                 <varname>Before=</varname>,
557                                 instead. For more details see
558                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
559                                 used, pass an integer value in the
560                                 range 0-99.</para></listitem>
561                         </varlistentry>
562
563                         <varlistentry>
564                                 <term><varname>KillMode=</varname></term>
565                                 <listitem><para>Specifies how
566                                 processes of this service shall be
567                                 killed. One of
568                                 <option>control-group</option>,
569                                 <option>process</option>,
570                                 <option>none</option>.</para>
571
572                                 <para>If set to
573                                 <option>control-group</option> all
574                                 remaining processes in the control
575                                 group of this service will be
576                                 terminated on service stop, after the
577                                 stop command (as configured with
578                                 <varname>ExecStop=</varname>) is
579                                 executed. If set to
580                                 <option>process</option> only the main
581                                 process itself is killed. If set to
582                                 <option>none</option> no process is
583                                 killed. In this case only the stop
584                                 command will be executed on service
585                                 stop, but no process be killed
586                                 otherwise. Processes remaining alive
587                                 after stop are left in their control
588                                 group and the control group continues
589                                 to exist after stop unless it is
590                                 empty. Defaults to
591                                 <option>control-group</option>.</para>
592
593                                 <para>Processes will first be
594                                 terminated via SIGTERM (unless the
595                                 signal to send is changed via
596                                 <varname>KillSignal=</varname>). If
597                                 then after a delay (configured via the
598                                 <varname>TimeoutSec=</varname> option)
599                                 processes still remain, the
600                                 termination request is repeated with
601                                 the SIGKILL signal (unless this is
602                                 disabled via the
603                                 <varname>SendSIGKILL=</varname>
604                                 option). See
605                                 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
606                                 for more
607                                 information.</para></listitem>
608                         </varlistentry>
609
610                         <varlistentry>
611                                 <term><varname>KillSignal=</varname></term>
612                                 <listitem><para>Specifies which signal
613                                 to use when killing a
614                                 service. Defaults to SIGTERM.
615                                 </para></listitem>
616                         </varlistentry>
617
618                         <varlistentry>
619                                 <term><varname>SendSIGKILL=</varname></term>
620                                 <listitem><para>Specifies whether to
621                                 send SIGKILL to remaining processes
622                                 after a timeout, if the normal
623                                 shutdown procedure left processes of
624                                 the service around. Takes a boolean
625                                 value. Defaults to "yes".
626                                 </para></listitem>
627                         </varlistentry>
628
629                         <varlistentry>
630                                 <term><varname>NonBlocking=</varname></term>
631                                 <listitem><para>Set O_NONBLOCK flag
632                                 for all file descriptors passed via
633                                 socket-based activation. If true, all
634                                 file descriptors >= 3 (i.e. all except
635                                 STDIN/STDOUT/STDERR) will have
636                                 the O_NONBLOCK flag set and hence are in
637                                 non-blocking mode. This option is only
638                                 useful in conjunction with a socket
639                                 unit, as described in
640                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
641                                 to false.</para></listitem>
642                         </varlistentry>
643
644                         <varlistentry>
645                                 <term><varname>NotifyAccess=</varname></term>
646                                 <listitem><para>Controls access to the
647                                 service status notification socket, as
648                                 accessible via the
649                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
650                                 call. Takes one of
651                                 <option>none</option> (the default),
652                                 <option>main</option> or
653                                 <option>all</option>. If
654                                 <option>none</option> no daemon status
655                                 updates are accepted from the service
656                                 processes, all status update messages
657                                 are ignored. If <option>main</option>
658                                 only service updates sent from the
659                                 main process of the service are
660                                 accepted. If <option>all</option> all
661                                 services updates from all members of
662                                 the service's control group are
663                                 accepted. This option must be set to
664                                 open access to the notification socket
665                                 when using
666                                 <varname>Type=notify</varname> (see above).</para></listitem>
667                         </varlistentry>
668
669                         <varlistentry>
670                                 <term><varname>Sockets=</varname></term>
671                                 <listitem><para>Specifies the name of
672                                 the socket units this service shall
673                                 inherit the sockets from when the
674                                 service is started. Normally it
675                                 should not be necessary to use this
676                                 setting as all sockets whose unit
677                                 shares the same name as the service
678                                 (ignoring the different suffix of course)
679                                 are passed to the spawned
680                                 process.</para>
681
682                                 <para>Note that the same socket may be
683                                 passed to multiple processes at the
684                                 same time. Also note that a different
685                                 service may be activated on incoming
686                                 traffic than inherits the sockets. Or
687                                 in other words: The
688                                 <varname>Service=</varname> setting of
689                                 <filename>.socket</filename> units
690                                 doesn't have to match the inverse of the
691                                 <varname>Sockets=</varname> setting of
692                                 the <filename>.service</filename> it
693                                 refers to.</para></listitem>
694                         </varlistentry>
695
696                         <varlistentry>
697                                 <term><varname>FsckPassNo=</varname></term>
698                                 <listitem><para>Set the fsck passno
699                                 priority to use to order this service
700                                 in relation to other file system
701                                 checking services. This option is only
702                                 necessary to fix ordering in relation
703                                 to fsck jobs automatically created for
704                                 all <filename>/etc/fstab</filename>
705                                 entries with a value in the fs_passno
706                                 column > 0. As such it should only be
707                                 used as option for fsck
708                                 services. Almost always it is a better
709                                 choice to add explicit ordering
710                                 directives via
711                                 <varname>After=</varname> or
712                                 <varname>Before=</varname>,
713                                 instead. For more details see
714                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
715                                 used, pass an integer value in the
716                                 same range as
717                                 <filename>/etc/fstab</filename>'s
718                                 fs_passno column. See
719                                 <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
720                                 for details.</para></listitem>
721                         </varlistentry>
722
723                 </variablelist>
724         </refsect1>
725
726         <refsect1>
727                   <title>See Also</title>
728                   <para>
729                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
730                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
731                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
732                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
733                   </para>
734         </refsect1>
735
736 </refentry>