man/systemd.service.xml

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   7   This file is part of systemd.
   8
   9   Copyright 2010 Lennart Poettering
  10
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  24
  25 <refentry id="systemd.service">
  26         <refentryinfo>
  27                 <title>systemd.service</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>systemd.service</refentrytitle>
  42                 <manvolnum>5</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>systemd.service</refname>
  47                 <refpurpose>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.target</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>PIDFile=</varname></term>
 220
 221                                 <listitem><para>Takes an absolute file
 222                                 name pointing to the PID file of this
 223                                 daemon. Use of this option is
 224                                 recommended for services where
 225                                 <varname>Type=</varname> is set to
 226                                 <option>forking</option>. systemd will
 227                                 read the PID of the main process of
 228                                 the daemon after start-up of the
 229                                 service. systemd will not write to the
 230                                 file configured here.</para>
 231                                 </listitem>
 232                         </varlistentry>
 233
 234                         <varlistentry>
 235                                 <term><varname>BusName=</varname></term>
 236
 237                                 <listitem><para>Takes a D-Bus bus
 238                                 name, where this service is reachable
 239                                 as. This option is mandatory for
 240                                 services where
 241                                 <varname>Type=</varname> is set to
 242                                 <option>dbus</option>, but its use
 243                                 is otherwise recommended as well if
 244                                 the process takes a name on the D-Bus
 245                                 bus.</para>
 246                                 </listitem>
 247                         </varlistentry>
 248
 249                         <varlistentry>
 250                                 <term><varname>ExecStart=</varname></term>
 251                                 <listitem><para>Takes a command line
 252                                 that is executed when this service
 253                                 shall be started up. The first token
 254                                 of the command line must be an
 255                                 absolute file name, then followed by
 256                                 arguments for the process. It is
 257                                 mandatory to set this option for all
 258                                 services. This option may not be
 259                                 specified more than once, except when
 260                                 <varname>Type=oneshot</varname> is
 261                                 used in which case more than one
 262                                 <varname>ExecStart=</varname> line is
 263                                 accepted which are then invoked one by
 264                                 one, sequentially in the order they
 265                                 appear in the unit file.</para>
 266
 267                                 <para>Optionally, if the absolute file
 268                                 name is prefixed with
 269                                 <literal>@</literal>, the second token
 270                                 will be passed as
 271                                 <literal>argv[0]</literal> to the
 272                                 executed process, followed by the
 273                                 further arguments specified. If the
 274                                 first token is prefixed with
 275                                 <literal>-</literal> an exit code of
 276                                 the command normally considered a
 277                                 failure (i.e. non-zero exit status or
 278                                 abnormal exit due to signal) is ignored
 279                                 and considered success. If both
 280                                 <literal>-</literal> and
 281                                 <literal>@</literal> are used for the
 282                                 same command the former must precede
 283                                 the latter. Unless
 284                                 <varname>Type=forking</varname> is
 285                                 set, the process started via this
 286                                 command line will be considered the
 287                                 main process of the daemon. The
 288                                 command line accepts % specifiers as
 289                                 described in
 290                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. On
 291                                 top of that basic environment variable
 292                                 substitution is supported, where
 293                                 <literal>${FOO}</literal> is replaced
 294                                 by the string value of the environment
 295                                 variable of the same name. Also
 296                                 <literal>$FOO</literal> may appear as
 297                                 separate word on the command line in
 298                                 which case the variable is replaced by
 299                                 its value split at whitespaces. Note
 300                                 that the first argument (i.e. the
 301                                 binary to execute) may not be a
 302                                 variable, and must be a literal and
 303                                 absolute path name.</para></listitem>
 304                         </varlistentry>
 305
 306                         <varlistentry>
 307                                 <term><varname>ExecStartPre=</varname></term>
 308                                 <term><varname>ExecStartPost=</varname></term>
 309                                 <listitem><para>Additional commands
 310                                 that are executed before (resp. after)
 311                                 the command in
 312                                 <varname>ExecStart=</varname>. Multiple
 313                                 command lines may be concatenated in a
 314                                 single directive, by separating them
 315                                 by semicolons (these semicolons must
 316                                 be passed as separate words). In that
 317                                 case, the commands are executed one
 318                                 after the other,
 319                                 serially. Alternatively, these
 320                                 directives may be specified more than
 321                                 once with the same effect. However,
 322                                 the latter syntax is not recommended
 323                                 for compatibility with parsers
 324                                 suitable for XDG
 325                                 <filename>.desktop</filename> files.
 326                                 Use of these settings is
 327                                 optional. Specifier and environment
 328                                 variable substitution is
 329                                 supported.</para></listitem>
 330                         </varlistentry>
 331
 332                         <varlistentry>
 333                                 <term><varname>ExecReload=</varname></term>
 334                                 <listitem><para>Commands to execute to
 335                                 trigger a configuration reload in the
 336                                 service. This argument takes multiple
 337                                 command lines, following the same
 338                                 scheme as pointed out for
 339                                 <varname>ExecStartPre=</varname>
 340                                 above. Use of this setting is
 341                                 optional. Specifier and environment
 342                                 variable substitution is supported
 343                                 here following the same scheme as for
 344                                 <varname>ExecStart=</varname>. One
 345                                 special environment variable is set:
 346                                 if known <literal>$MAINPID</literal> is
 347                                 set to the main process of the
 348                                 daemon, and may be used for command
 349                                 lines like the following:
 350                                 <command>/bin/kill -HUP
 351                                 $MAINPID</command>.</para></listitem>
 352                         </varlistentry>
 353
 354                         <varlistentry>
 355                                 <term><varname>ExecStop=</varname></term>
 356                                 <listitem><para>Commands to execute to
 357                                 stop the service started via
 358                                 <varname>ExecStart=</varname>. This
 359                                 argument takes multiple command lines,
 360                                 following the same scheme as pointed
 361                                 out for
 362                                 <varname>ExecStartPre=</varname>
 363                                 above. Use of this setting is
 364                                 optional. All processes remaining for
 365                                 a service after the commands
 366                                 configured in this option are run are
 367                                 terminated according to the
 368                                 <varname>KillMode=</varname> setting
 369                                 (see below). If this option is not
 370                                 specified the process is terminated
 371                                 right-away when service stop is
 372                                 requested. Specifier and environment
 373                                 variable substitution is supported
 374                                 (including
 375                                 <literal>$MAINPID</literal>, see
 376                                 above).</para></listitem>
 377                         </varlistentry>
 378
 379                         <varlistentry>
 380                                 <term><varname>ExecStopPost=</varname></term>
 381                                 <listitem><para>Additional commands
 382                                 that are executed after the service
 383                                 was stopped using the commands
 384                                 configured in
 385                                 <varname>ExecStop=</varname>. This
 386                                 argument takes multiple command lines,
 387                                 following the same scheme as pointed
 388                                 out for
 389                                 <varname>ExecStartPre</varname>. Use
 390                                 of these settings is
 391                                 optional. Specifier and environment
 392                                 variable substitution is
 393                                 supported.</para></listitem>
 394                         </varlistentry>
 395
 396                         <varlistentry>
 397                                 <term><varname>RestartSec=</varname></term>
 398                                 <listitem><para>Configures the time to
 399                                 sleep before restarting a service (as
 400                                 configured with
 401                                 <varname>Restart=</varname>). Takes a
 402                                 unit-less value in seconds, or a time
 403                                 span value such as "5min
 404                                 20s". Defaults to
 405                                 100ms.</para></listitem>
 406                         </varlistentry>
 407
 408                         <varlistentry>
 409                                 <term><varname>TimeoutSec=</varname></term>
 410                                 <listitem><para>Configures the time to
 411                                 wait for start-up and stop. If a
 412                                 daemon service does not signal
 413                                 start-up completion within the
 414                                 configured time the service will be
 415                                 considered failed and be shut down
 416                                 again. If a service is asked to stop
 417                                 but does not terminate in the
 418                                 specified time it will be terminated
 419                                 forcibly via SIGTERM, and after
 420                                 another delay of this time with
 421                                 SIGKILL. (See
 422                                 <varname>KillMode=</varname>
 423                                 below.) Takes a unit-less value in seconds, or a
 424                                 time span value such as "5min
 425                                 20s". Pass 0 to disable the timeout
 426                                 logic. Defaults to
 427                                 60s.</para></listitem>
 428                         </varlistentry>
 429
 430                         <varlistentry>
 431                                 <term><varname>Restart=</varname></term>
 432                                 <listitem><para>Configures whether the
 433                                 main service process shall be
 434                                 restarted when it exits. Takes one of
 435                                 <option>no</option>,
 436                                 <option>on-success</option>,
 437                                 <option>on-failure</option>,
 438                                 <option>on-abort</option> or
 439                                 <option>always</option>. If set to
 440                                 <option>no</option> (the default) the
 441                                 service will not be restarted when it
 442                                 exits. If set to
 443                                 <option>on-success</option> it will be
 444                                 restarted only when it exited cleanly,
 445                                 i.e. terminated with an exit code of
 446                                 0. If set to
 447                                 <option>on-failure</option> it will be
 448                                 restarted only when it exited with an
 449                                 exit code not equalling 0, or when
 450                                 terminated by a signal. If set to
 451                                 <option>on-abort</option> it will be
 452                                 restarted only if it exits due to
 453                                 reception of an uncaught signal. If
 454                                 set to <option>always</option> the
 455                                 service will be restarted regardless
 456                                 whether it exited cleanly or not, or
 457                                 got terminated abnormally by a
 458                                 signal.</para></listitem>
 459                         </varlistentry>
 460
 461                         <varlistentry>
 462                                 <term><varname>PermissionsStartOnly=</varname></term>
 463                                 <listitem><para>Takes a boolean
 464                                 argument. If true, the permission
 465                                 related execution options as
 466                                 configured with
 467                                 <varname>User=</varname> and similar
 468                                 options (see
 469                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 470                                 for more information) are only applied
 471                                 to the process started with
 472                                 <varname>ExecStart=</varname>, and not
 473                                 to the various other
 474                                 <varname>ExecStartPre=</varname>,
 475                                 <varname>ExecStartPost=</varname>,
 476                                 <varname>ExecReload=</varname>,
 477                                 <varname>ExecStop=</varname>,
 478                                 <varname>ExecStopPost=</varname>
 479                                 commands. If false, the setting is
 480                                 applied to all configured commands the
 481                                 same way. Defaults to
 482                                 false.</para></listitem>
 483                         </varlistentry>
 484
 485                         <varlistentry>
 486                                 <term><varname>RootDirectoryStartOnly=</varname></term>
 487                                 <listitem><para>Takes a boolean
 488                                 argument. If true, the root directory
 489                                 as configured with the
 490                                 <varname>RootDirectory=</varname>
 491                                 option (see
 492                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 493                                 for more information) is only applied
 494                                 to the process started with
 495                                 <varname>ExecStart=</varname>, and not
 496                                 to the various other
 497                                 <varname>ExecStartPre=</varname>,
 498                                 <varname>ExecStartPost=</varname>,
 499                                 <varname>ExecReload=</varname>,
 500                                 <varname>ExecStop=</varname>,
 501                                 <varname>ExecStopPost=</varname>
 502                                 commands. If false, the setting is
 503                                 applied to all configured commands the
 504                                 same way. Defaults to
 505                                 false.</para></listitem>
 506                         </varlistentry>
 507
 508                         <varlistentry>
 509                                 <term><varname>SysVStartPriority=</varname></term>
 510                                 <listitem><para>Set the SysV start
 511                                 priority to use to order this service
 512                                 in relation to SysV services lacking
 513                                 LSB headers. This option is only
 514                                 necessary to fix ordering in relation
 515                                 to legacy SysV services, that have no
 516                                 ordering information encoded in the
 517                                 script headers. As such it should only
 518                                 be used as temporary compatibility
 519                                 option, and not be used in new unit
 520                                 files. Almost always it is a better
 521                                 choice to add explicit ordering
 522                                 directives via
 523                                 <varname>After=</varname> or
 524                                 <varname>Before=</varname>,
 525                                 instead. For more details see
 526                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
 527                                 used, pass an integer value in the
 528                                 range 0-99.</para></listitem>
 529                         </varlistentry>
 530
 531                         <varlistentry>
 532                                 <term><varname>KillMode=</varname></term>
 533                                 <listitem><para>Specifies how
 534                                 processes of this service shall be
 535                                 killed. One of
 536                                 <option>control-group</option>,
 537                                 <option>process-group</option>,
 538                                 <option>process</option>,
 539                                 <option>none</option>.</para>
 540
 541                                 <para>If set to
 542                                 <option>control-group</option> all
 543                                 remaining processes in the control
 544                                 group of this service will be
 545                                 terminated on service stop, after the
 546                                 stop command (as configured with
 547                                 <varname>ExecStop=</varname>) is
 548                                 executed. If set to
 549                                 <option>process-group</option> only
 550                                 the members of the process group of
 551                                 the main service process are
 552                                 killed. If set to
 553                                 <option>process</option> only the main
 554                                 process itself is killed. If set to
 555                                 <option>none</option> no process is
 556                                 killed. In this case only the stop
 557                                 command will be executed on service
 558                                 stop, but no process be killed
 559                                 otherwise. Processes remaining alive
 560                                 after stop are left in their control
 561                                 group and the control group continues
 562                                 to exist after stop unless it is
 563                                 empty. Defaults to
 564                                 <option>control-group</option>.</para>
 565
 566                                 <para>Processes will first be
 567                                 terminated via SIGTERM (unless the
 568                                 signal to send is changed via
 569                                 <varname>KillSignal=</varname>). If
 570                                 then after a delay (configured via the
 571                                 <varname>TimeoutSec=</varname> option)
 572                                 processes still remain, the
 573                                 termination request is repeated with
 574                                 the SIGKILL signal (unless this is
 575                                 disabled via the
 576                                 <varname>SendSIGKILL=</varname>
 577                                 option). See
 578                                 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 579                                 for more
 580                                 information.</para></listitem>
 581                         </varlistentry>
 582
 583                         <varlistentry>
 584                                 <term><varname>KillSignal=</varname></term>
 585                                 <listitem><para>Specifies which signal
 586                                 to use when killing a
 587                                 service. Defaults to SIGTERM.
 588                                 </para></listitem>
 589                         </varlistentry>
 590
 591                         <varlistentry>
 592                                 <term><varname>SendSIGKILL=</varname></term>
 593                                 <listitem><para>Specifies whether to
 594                                 send SIGKILL to remaining processes
 595                                 after a timeout, if the normal
 596                                 shutdown procedure left processes of
 597                                 the service around. Takes a boolean
 598                                 value. Defaults to "yes".
 599                                 </para></listitem>
 600                         </varlistentry>
 601
 602                         <varlistentry>
 603                                 <term><varname>NonBlocking=</varname></term>
 604                                 <listitem><para>Set O_NONBLOCK flag
 605                                 for all file descriptors passed via
 606                                 socket-based activation. If true, all
 607                                 file descriptors >= 3 (i.e. all except
 608                                 STDIN/STDOUT/STDERR) will have
 609                                 the O_NONBLOCK flag set and hence are in
 610                                 non-blocking mode. This option is only
 611                                 useful in conjunction with a socket
 612                                 unit, as described in
 613                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
 614                                 to false.</para></listitem>
 615                         </varlistentry>
 616
 617                         <varlistentry>
 618                                 <term><varname>NotifyAccess=</varname></term>
 619                                 <listitem><para>Controls access to the
 620                                 service status notification socket, as
 621                                 accessible via the
 622                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 623                                 call. Takes one of
 624                                 <option>none</option> (the default),
 625                                 <option>main</option> or
 626                                 <option>all</option>. If
 627                                 <option>none</option> no daemon status
 628                                 updates are accepted from the service
 629                                 processes, all status update messages
 630                                 are ignored. If <option>main</option>
 631                                 only service updates sent from the
 632                                 main process of the service are
 633                                 accepted. If <option>all</option> all
 634                                 services updates from all members of
 635                                 the service's control group are
 636                                 accepted. This option must be set to
 637                                 open access to the notification socket
 638                                 when using
 639                                 <varname>Type=notify</varname> (see above).</para></listitem>
 640                         </varlistentry>
 641
 642                         <varlistentry>
 643                                 <term><varname>Sockets=</varname></term>
 644                                 <listitem><para>Specifies the name of
 645                                 the socket units this service shall
 646                                 inherit the sockets from when the
 647                                 service (ignoring the different suffix
 648                                 of course) is started. Normally it
 649                                 should not be necessary to use this
 650                                 setting as all sockets whose unit
 651                                 shares the same name as the service
 652                                 are passed to the spawned
 653                                 process.</para>
 654
 655                                 <para>Note that the same socket may be
 656                                 passed to multiple processes at the
 657                                 same time. Also note that a different
 658                                 service may be activated on incoming
 659                                 traffic than inherits the sockets. Or
 660                                 in other words: The
 661                                 <varname>Service=</varname> setting of
 662                                 <filename>.socket</filename> units
 663                                 doesn't have to match the inverse of the
 664                                 <varname>Sockets=</varname> setting of
 665                                 the <filename>.service</filename> it
 666                                 refers to.</para></listitem>
 667                         </varlistentry>
 668
 669                         <varlistentry>
 670                                 <term><varname>FsckPassNo=</varname></term>
 671                                 <listitem><para>Set the fsck passno
 672                                 priority to use to order this service
 673                                 in relation to other file system
 674                                 checking services. This option is only
 675                                 necessary to fix ordering in relation
 676                                 to fsck jobs automatically created for
 677                                 all <filename>/etc/fstab</filename>
 678                                 entries with a value in the fs_passno
 679                                 column > 0. As such it should only be
 680                                 used as option for fsck
 681                                 services. Almost always it is a better
 682                                 choice to add explicit ordering
 683                                 directives via
 684                                 <varname>After=</varname> or
 685                                 <varname>Before=</varname>,
 686                                 instead. For more details see
 687                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
 688                                 used, pass an integer value in the
 689                                 same range as
 690                                 <filename>/etc/fstab</filename>'s
 691                                 fs_passno column. See
 692                                 <citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 693                                 for details.</para></listitem>
 694                         </varlistentry>
 695
 696                 </variablelist>
 697         </refsect1>
 698
 699         <refsect1>
 700                   <title>See Also</title>
 701                   <para>
 702                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 703                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 704                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 705                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 706                   </para>
 707         </refsect1>
 708
 709 </refentry>