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>finish</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, communication channels must be
 133                                 installed before the daemon is started
 134                                 up (e.g. sockets set up by systemd,
 135                                 via socket activation), as systemd
 136                                 will immediately proceed starting
 137                                 follow-up units.</para>
 138
 139                                 <para>If set to
 140                                 <option>forking</option> it is
 141                                 expected that the process configured
 142                                 with <varname>ExecStart=</varname>
 143                                 will start up and call
 144                                 <function>fork()</function>. The
 145                                 parent process is expected to finish
 146                                 when start-up is complete and all
 147                                 communication channels set up. The
 148                                 child continues to run as the main
 149                                 daemon process. This is the behaviour
 150                                 of traditional UNIX daemons. If this
 151                                 setting is used, it is recommended to
 152                                 also use the
 153                                 <varname>PIDFile=</varname> option, so
 154                                 that systemd can identify the main
 155                                 process of the daemon. systemd will
 156                                 proceed starting follow-up units as
 157                                 soon as the parent process
 158                                 exits.</para>
 159
 160                                 <para>Behaviour of
 161                                 <option>finish</option> is similar
 162                                 to <option>simple</option>, however
 163                                 it is expected that the process has to
 164                                 exit before systemd starts follow-up
 165                                 units. <varname>ValidNoProcess=</varname>
 166                                 is particularly useful for this type
 167                                 of service.</para>
 168
 169                                 <para>Behaviour of
 170                                 <option>dbus</option> is similar to
 171                                 <option>simple</option>, however it is
 172                                 expected that the daemon acquires a
 173                                 name on the D-Bus bus, as configured
 174                                 by
 175                                 <varname>BusName=</varname>. systemd
 176                                 will proceed starting follow-up units
 177                                 after the D-Bus bus name has been
 178                                 acquired. Service units with this
 179                                 option configured implicitly have
 180                                 dependencies on the
 181                                 <filename>dbus.target</filename>
 182                                 unit.</para>
 183
 184                                 <para>Behaviour of
 185                                 <option>notify</option> is similar to
 186                                 <option>simple</option>, however it is
 187                                 expected that the daemon sends a
 188                                 notification message via
 189                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 190                                 or an equivalent call when it finished
 191                                 starting up. systemd will proceed
 192                                 starting follow-up units after this
 193                                 notification message has been sent. If
 194                                 this option is used
 195                                 <varname>NotifyAccess=</varname> (see
 196                                 below) must be set to open access to
 197                                 the notification socket provided by
 198                                 systemd. If
 199                                 <varname>NotifyAccess=</varname> is not
 200                                 set, it will be implicitly set to
 201                                 <option>main</option>.</para>
 202                                 </listitem>
 203                         </varlistentry>
 204
 205                         <varlistentry>
 206                                 <term><varname>ValidNoProcess=</varname></term>
 207
 208                                 <listitem><para>Takes a boolean value
 209                                 that specifies whether the service
 210                                 shall be considered active even when
 211                                 all its processes exited. Defaults to
 212                                 <option>no</option>.</para>
 213                                 </listitem>
 214                         </varlistentry>
 215
 216                         <varlistentry>
 217                                 <term><varname>PIDFile=</varname></term>
 218
 219                                 <listitem><para>Takes an absolute file
 220                                 name pointing to the PID file of this
 221                                 daemon. Use of this option is
 222                                 recommended for services where
 223                                 <varname>Type=</varname> is set to
 224                                 <option>forking</option>.</para>
 225                                 </listitem>
 226                         </varlistentry>
 227
 228                         <varlistentry>
 229                                 <term><varname>BusName=</varname></term>
 230
 231                                 <listitem><para>Takes a D-Bus bus
 232                                 name, where this service is reachable
 233                                 as. This option is mandatory for
 234                                 services where
 235                                 <varname>Type=</varname> is set to
 236                                 <option>dbus</option>, but its use
 237                                 is otherwise recommended as well if
 238                                 the process takes a name on the D-Bus
 239                                 bus.</para>
 240                                 </listitem>
 241                         </varlistentry>
 242
 243                         <varlistentry>
 244                                 <term><varname>ExecStart=</varname></term>
 245                                 <listitem><para>Takes a command line
 246                                 that is executed when this service
 247                                 shall be started up. The first token
 248                                 of the command line must be an
 249                                 absolute file name, then followed by
 250                                 arguments for the process. It is
 251                                 mandatory to set this option for all
 252                                 services. This option may not be
 253                                 specified more than once. Optionally,
 254                                 if the absolute file name is prefixed
 255                                 with <literal>@</literal>, the second
 256                                 token will be passed as
 257                                 <literal>argv[0]</literal> to the
 258                                 executed process, followed by the
 259                                 further arguments specified. If the
 260                                 first token is prefixed with
 261                                 <literal>-</literal> an error code of
 262                                 the command normally considered a
 263                                 failure is ignored and considered
 264                                 success. If both <literal>-</literal>
 265                                 and <literal>@</literal> are used for
 266                                 the same command the latter must
 267                                 preceed the latter. Unless
 268                                 <varname>Type=forking</varname> is
 269                                 set, the process started via this
 270                                 command line will be considered the
 271                                 main process of the daemon. The
 272                                 command line accepts % specifiers as
 273                                 described in
 274                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. On
 275                                 top of that basic environment variable
 276                                 substitution is supported, where
 277                                 <literal>${FOO}</literal> is replaced
 278                                 by the string value of the environment
 279                                 variable of the same name. Also
 280                                 <literal>$FOO</literal> may appear as
 281                                 seperate word on the command line in
 282                                 which case the variable is replaced by
 283                                 its value split at
 284                                 whitespaces.</para></listitem>
 285                         </varlistentry>
 286
 287                         <varlistentry>
 288                                 <term><varname>ExecStartPre=</varname></term>
 289                                 <term><varname>ExecStartPost=</varname></term>
 290                                 <listitem><para>Additional commands
 291                                 that are executed before (resp. after)
 292                                 the command in
 293                                 <varname>ExecStart=</varname>. Multiple
 294                                 command lines may be concatenated in a
 295                                 single directive, by seperating them
 296                                 by semicolons (these semicolons must
 297                                 be passed as seperate words). In that
 298                                 case, the commands are executed one
 299                                 after the other,
 300                                 serially. Alternatively, these
 301                                 directives may be specified more than
 302                                 once whith the same effect. However,
 303                                 the latter syntax is not recommended
 304                                 for compatibility with parsers
 305                                 suitable for XDG
 306                                 <filename>.desktop</filename> files.
 307                                 Use of these settings is
 308                                 optional. Specifier and environment
 309                                 variable substitution is
 310                                 supported.</para></listitem>
 311                         </varlistentry>
 312
 313                         <varlistentry>
 314                                 <term><varname>ExecReload=</varname></term>
 315                                 <listitem><para>Commands to execute to
 316                                 trigger a configuration reload in the
 317                                 service. This argument takes multiple
 318                                 command lines, following the same
 319                                 scheme as pointed out for
 320                                 <varname>ExecStartPre=</varname>
 321                                 above. Use of this setting is
 322                                 optional. Specifier and environment
 323                                 variable substitution is supported
 324                                 here following the same scheme as for
 325                                 <varname>ExecStart=</varname>. One
 326                                 special environment variable is set:
 327                                 if known <literal>$MAINPID</literal> is
 328                                 set to the main process of the
 329                                 daemon, and may be used for command
 330                                 lines like the following:
 331                                 <command>/bin/kill -HUP
 332                                 $(MAINPID)</command>.</para></listitem>
 333                         </varlistentry>
 334
 335                         <varlistentry>
 336                                 <term><varname>ExecStop=</varname></term>
 337                                 <listitem><para>Commands to execute to
 338                                 stop the service started via
 339                                 <varname>ExecStart=</varname>. This
 340                                 argument takes multiple command lines,
 341                                 following the same scheme as pointed
 342                                 out for
 343                                 <varname>ExecStartPre=</varname>
 344                                 above. Use of this setting is
 345                                 optional. All processes remaining for
 346                                 a service after the commands
 347                                 configured in this option are run are
 348                                 terminated according to the
 349                                 <varname>KillMode=</varname> setting
 350                                 (see below). If this option is not
 351                                 specified the process is terminated
 352                                 right-away when service stop is
 353                                 requested. Specifier and environment
 354                                 variable substitution is supported
 355                                 (including
 356                                 <literal>$(MAINPID)</literal>, see
 357                                 above).</para></listitem>
 358                         </varlistentry>
 359
 360                         <varlistentry>
 361                                 <term><varname>ExecStopPost=</varname></term>
 362                                 <listitem><para>Additional commands
 363                                 that are executed after the service
 364                                 was stopped using the commands
 365                                 configured in
 366                                 <varname>ExecStop=</varname>. This
 367                                 argument takes multiple command lines,
 368                                 following the same scheme as pointed
 369                                 out for
 370                                 <varname>ExecStartPre</varname>. Use
 371                                 of these settings is
 372                                 optional. Specifier and environment
 373                                 variable substitution is
 374                                 supported.</para></listitem>
 375                         </varlistentry>
 376
 377                         <varlistentry>
 378                                 <term><varname>RestartSec=</varname></term>
 379                                 <listitem><para>Configures the time to
 380                                 sleep before restarting a service (as
 381                                 configured with
 382                                 <varname>Restart=</varname>). Takes a
 383                                 unit-less value in seconds, or a time
 384                                 span value such as "5min
 385                                 20s". Defaults to
 386                                 100ms.</para></listitem>
 387                         </varlistentry>
 388
 389                         <varlistentry>
 390                                 <term><varname>TimeoutSec=</varname></term>
 391                                 <listitem><para>Configures the time to
 392                                 wait for start-up and stop. If a
 393                                 daemon service does not signal
 394                                 start-up completion within the
 395                                 configured time the service will be
 396                                 considered failed and be shut down
 397                                 again. If a service is asked to stop
 398                                 but does not terminate in the
 399                                 specified time it will be terminated
 400                                 forcibly via SIGTERM, and after
 401                                 another delay of this time with
 402                                 SIGKILL. (See
 403                                 <varname>KillMode=</varname>
 404                                 below.) Takes a unit-less value in seconds, or a
 405                                 time span value such as "5min
 406                                 20s". Pass 0 to disable the timeout
 407                                 logic. Defaults to
 408                                 60s.</para></listitem>
 409                         </varlistentry>
 410
 411                         <varlistentry>
 412                                 <term><varname>Restart=</varname></term>
 413                                 <listitem><para>Configures whether the
 414                                 main service process shall be restarted when
 415                                 it exists. Takes one of
 416                                 <option>once</option>,
 417                                 <option>restart-on-success</option> or
 418                                 <option>restart-always</option>. If
 419                                 set to <option>once</option> (the
 420                                 default) the service will not be
 421                                 restarted when it exits. If set to
 422                                 <option>restart-on-success</option> it
 423                                 will be restarted only when it exited
 424                                 cleanly, i.e. terminated with an exit
 425                                 code of 0. If set to
 426                                 <option>restart-always</option> the
 427                                 service will be restarted regardless
 428                                 whether it exited cleanly or not, or
 429                                 got terminated abnormally by a
 430                                 signal.</para></listitem>
 431                         </varlistentry>
 432
 433                         <varlistentry>
 434                                 <term><varname>PermissionsStartOnly=</varname></term>
 435                                 <listitem><para>Takes a boolean
 436                                 argument. If true, the permission
 437                                 related execution options as
 438                                 configured with
 439                                 <varname>User=</varname> and similar
 440                                 options (see
 441                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 442                                 for more information) are only applied
 443                                 to the process started with
 444                                 <varname>ExecStart=</varname>, and not
 445                                 to the various other
 446                                 <varname>ExecStartPre=</varname>,
 447                                 <varname>ExecStartPost=</varname>,
 448                                 <varname>ExecReload=</varname>,
 449                                 <varname>ExecStop=</varname>,
 450                                 <varname>ExecStopPost=</varname>
 451                                 commands. If false, the setting is
 452                                 applied to all configured commands the
 453                                 same way. Defaults to
 454                                 false.</para></listitem>
 455                         </varlistentry>
 456
 457                         <varlistentry>
 458                                 <term><varname>RootDirectoryStartOnly=</varname></term>
 459                                 <listitem><para>Takes a boolean
 460                                 argument. If true, the root directory
 461                                 as configured with the
 462                                 <varname>RootDirectory=</varname>
 463                                 option (see
 464                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 465                                 for more information) is only applied
 466                                 to the process started with
 467                                 <varname>ExecStart=</varname>, and not
 468                                 to the various other
 469                                 <varname>ExecStartPre=</varname>,
 470                                 <varname>ExecStartPost=</varname>,
 471                                 <varname>ExecReload=</varname>,
 472                                 <varname>ExecStop=</varname>,
 473                                 <varname>ExecStopPost=</varname>
 474                                 commands. If false, the setting is
 475                                 applied to all configured commands the
 476                                 same way. Defaults to
 477                                 false.</para></listitem>
 478                         </varlistentry>
 479
 480                         <varlistentry>
 481                                 <term><varname>SysVStartPriority=</varname></term>
 482                                 <listitem><para>Set the SysV start
 483                                 priority to use to order this service
 484                                 in relation to SysV services lacking
 485                                 LSB headers. This option is only
 486                                 necessary to fix ordering in relation
 487                                 to legacy SysV services, that have no
 488                                 ordering information encoded in the
 489                                 script headers. As such it should only
 490                                 be used as temporary compatibility
 491                                 option, and not be used in new unit
 492                                 files. Almost always it is a better
 493                                 choice to add explicit ordering
 494                                 directives via
 495                                 <varname>After=</varname> or
 496                                 <varname>Before=</varname>,
 497                                 instead. For more details see
 498                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
 499                                 used, pass an integer value in the
 500                                 range 0-99.</para></listitem>
 501                         </varlistentry>
 502
 503                         <varlistentry>
 504                                 <term><varname>KillMode=</varname></term>
 505                                 <listitem><para>Specifies how
 506                                 processes of this service shall be
 507                                 killed. One of
 508                                 <option>control-group</option>,
 509                                 <option>process-group</option>,
 510                                 <option>process</option>,
 511                                 <option>none</option>.</para>
 512
 513                                 <para>If set to
 514                                 <option>control-group</option> all
 515                                 remaining processes in the control
 516                                 group of this service will be
 517                                 terminated on service stop, after the
 518                                 stop command (as configured with
 519                                 <varname>ExecStop=</varname>) is
 520                                 executed. If set to
 521                                 <option>process-group</option> only
 522                                 the members of the process group of
 523                                 the main service process are
 524                                 killed. If set to
 525                                 <option>process</option> only the main
 526                                 process itself is killed. If set to
 527                                 <option>none</option> no process is
 528                                 killed. In this case only the stop
 529                                 command will be executed on service
 530                                 stop, but no process be killed
 531                                 otherwise. Processes remaining alive
 532                                 after stop are left in their control
 533                                 group and the control group continues
 534                                 to exist after stop unless it is
 535                                 empty. Defaults to
 536                                 <option>control-croup</option>.</para>
 537
 538                                 <para>Processes will first be
 539                                 terminated via SIGTERM. If then after
 540                                 a delay (configured via the
 541                                 <varname>TimeoutSec=</varname> option)
 542                                 processes still remain, the
 543                                 termination request is repeated with
 544                                 the SIGKILL signal. See
 545                                 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 546                                 for more
 547                                 information.</para></listitem>
 548                         </varlistentry>
 549
 550                         <varlistentry>
 551                                 <term><varname>NonBlocking=</varname></term>
 552                                 <listitem><para>Set O_NONBLOCK flag
 553                                 for all file descriptors passed via
 554                                 socket-based activation. If true, all
 555                                 file descriptors >= 3 (i.e. all except
 556                                 STDIN/STDOUT/STDERR) will have
 557                                 the O_NONBLOCK flag set and hence are in
 558                                 non-blocking mode. This option is only
 559                                 useful in conjunction with a socket
 560                                 unit, as described in
 561                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
 562                                 to false.</para></listitem>
 563                         </varlistentry>
 564
 565                         <varlistentry>
 566                                 <term><varname>NotifyAccess=</varname></term>
 567                                 <listitem><para>Controls access to the
 568                                 service status notification socket, as
 569                                 accessible via the
 570                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 571                                 call. Takes one of
 572                                 <option>none</option> (the default),
 573                                 <option>main</option> or
 574                                 <option>all</option>. If
 575                                 <option>none</option> no daemon status
 576                                 updates are accepted by the service
 577                                 processes, all status update messages
 578                                 are ignored. If <option>main</option>
 579                                 only service updates sent from the
 580                                 main process of the service are
 581                                 accepted. If <option>all</option> all
 582                                 services updates from all members of
 583                                 the service's control group are
 584                                 accepted. This option must be set to
 585                                 open access to the notification socket
 586                                 when using
 587                                 <varname>Type=notify</varname> (see above).</para></listitem>
 588                         </varlistentry>
 589
 590                 </variablelist>
 591         </refsect1>
 592
 593         <refsect1>
 594                   <title>See Also</title>
 595                   <para>
 596                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 597                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 598                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 599                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 600                   </para>
 601         </refsect1>
 602
 603 </refentry>