man/systemd.service.xml

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   7   This file is part of systemd.
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   9   Copyright 2010 Lennart Poettering
  10
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  24
  25 <refentry id="systemd.service">
  26         <refentryinfo>
  27                 <title>systemd.service</title>
  28                 <productname>systemd</productname>
  29
  30                 <authorgroup>
  31                         <author>
  32                                 <contrib>Developer</contrib>
  33                                 <firstname>Lennart</firstname>
  34                                 <surname>Poettering</surname>
  35                                 <email>lennart@poettering.net</email>
  36                         </author>
  37                 </authorgroup>
  38         </refentryinfo>
  39
  40         <refmeta>
  41                 <refentrytitle>systemd.service</refentrytitle>
  42                 <manvolnum>5</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>systemd.service</refname>
  47                 <refpurpose>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. Unless
 260                                 <varname>Type=forking</varname> is
 261                                 set, the process started via this
 262                                 command line will be considered the
 263                                 main process of the daemon. The
 264                                 command line accepts % specifiers as
 265                                 described in
 266                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. On
 267                                 top of that basic environment variable
 268                                 substitution is supported, where
 269                                 <literal>$(FOO)</literal> is replaced
 270                                 by the value of the environment
 271                                 variable of the same
 272                                 name.</para></listitem>
 273                         </varlistentry>
 274
 275                         <varlistentry>
 276                                 <term><varname>ExecStartPre=</varname></term>
 277                                 <term><varname>ExecStartPost=</varname></term>
 278                                 <listitem><para>Additional commands
 279                                 that are executed before (resp. after)
 280                                 the command in
 281                                 <varname>ExecStart=</varname>. Multiple
 282                                 command lines may be concatenated in a
 283                                 single directive, by seperating them
 284                                 by semicolons (these semicolons must
 285                                 be passed as seperate words). In that
 286                                 case, the commands are executed one
 287                                 after the other,
 288                                 serially. Alternatively, these
 289                                 directives may be specified more than
 290                                 once whith the same effect. However,
 291                                 the latter syntax is not recommended
 292                                 for compatibility with parsers
 293                                 suitable for XDG
 294                                 <filename>.desktop</filename> files.
 295                                 Use of these settings is
 296                                 optional. Specifier and environment
 297                                 variable substitution is
 298                                 supported.</para></listitem>
 299                         </varlistentry>
 300
 301                         <varlistentry>
 302                                 <term><varname>ExecReload=</varname></term>
 303                                 <listitem><para>Commands to execute to
 304                                 trigger a configuration reload in the
 305                                 service. This argument takes multiple
 306                                 command lines, following the same
 307                                 scheme as pointed out for
 308                                 <varname>ExecStartPre=</varname>
 309                                 above. Use of this setting is
 310                                 optional. Specifier and environment
 311                                 variable substitution is supported
 312                                 here following the same scheme as for
 313                                 <varname>ExecStart=</varname>. One
 314                                 special environment variable is set:
 315                                 if known <literal>$MAINPID</literal> is
 316                                 set to the main process of the
 317                                 daemon, and may be used for command
 318                                 lines like the following:
 319                                 <command>/bin/kill -HUP
 320                                 $(MAINPID)</command>.</para></listitem>
 321                         </varlistentry>
 322
 323                         <varlistentry>
 324                                 <term><varname>ExecStop=</varname></term>
 325                                 <listitem><para>Commands to execute to
 326                                 stop the service started via
 327                                 <varname>ExecStart=</varname>. This
 328                                 argument takes multiple command lines,
 329                                 following the same scheme as pointed
 330                                 out for
 331                                 <varname>ExecStartPre=</varname>
 332                                 above. Use of this setting is
 333                                 optional. All processes remaining for
 334                                 a service after the commands
 335                                 configured in this option are run are
 336                                 terminated according to the
 337                                 <varname>KillMode=</varname> setting
 338                                 (see below). If this option is not
 339                                 specified the process is terminated
 340                                 right-away when service stop is
 341                                 requested. Specifier and environment
 342                                 variable substitution is supported
 343                                 (including
 344                                 <literal>$(MAINPID)</literal>, see
 345                                 above).</para></listitem>
 346                         </varlistentry>
 347
 348                         <varlistentry>
 349                                 <term><varname>ExecStopPost=</varname></term>
 350                                 <listitem><para>Additional commands
 351                                 that are executed after the service
 352                                 was stopped using the commands
 353                                 configured in
 354                                 <varname>ExecStop=</varname>. This
 355                                 argument takes multiple command lines,
 356                                 following the same scheme as pointed
 357                                 out for
 358                                 <varname>ExecStartPre</varname>. Use
 359                                 of these settings is
 360                                 optional. Specifier and environment
 361                                 variable substitution is
 362                                 supported.</para></listitem>
 363                         </varlistentry>
 364
 365                         <varlistentry>
 366                                 <term><varname>RestartSec=</varname></term>
 367                                 <listitem><para>Configures the time to
 368                                 sleep before restarting a service (as
 369                                 configured with
 370                                 <varname>Restart=</varname>). Takes a
 371                                 unit-less value in seconds, or a time
 372                                 span value such as "5min
 373                                 20s". Defaults to
 374                                 100ms.</para></listitem>
 375                         </varlistentry>
 376
 377                         <varlistentry>
 378                                 <term><varname>TimeoutSec=</varname></term>
 379                                 <listitem><para>Configures the time to
 380                                 wait for start-up and stop. If a
 381                                 daemon service does not signal
 382                                 start-up completion within the
 383                                 configured time the service will be
 384                                 considered failed and be shut down
 385                                 again. If a service is asked to stop
 386                                 but does not terminate in the
 387                                 specified time it will be terminated
 388                                 forcibly via SIGTERM, and after
 389                                 another delay of this time with
 390                                 SIGKILL. (See
 391                                 <varname>KillMode=</varname>
 392                                 below.) Takes a unit-less value in seconds, or a
 393                                 time span value such as "5min
 394                                 20s". Pass 0 to disable the timeout
 395                                 logic. Defaults to
 396                                 60s.</para></listitem>
 397                         </varlistentry>
 398
 399                         <varlistentry>
 400                                 <term><varname>Restart=</varname></term>
 401                                 <listitem><para>Configures whether the
 402                                 main service process shall be restarted when
 403                                 it exists. Takes one of
 404                                 <option>once</option>,
 405                                 <option>restart-on-success</option> or
 406                                 <option>restart-always</option>. If
 407                                 set to <option>once</option> (the
 408                                 default) the service will not be
 409                                 restarted when it exits. If set to
 410                                 <option>restart-on-success</option> it
 411                                 will be restarted only when it exited
 412                                 cleanly, i.e. terminated with an exit
 413                                 code of 0. If set to
 414                                 <option>restart-always</option> the
 415                                 service will be restarted regardless
 416                                 whether it exited cleanly or not, or
 417                                 got terminated abnormally by a
 418                                 signal.</para></listitem>
 419                         </varlistentry>
 420
 421                         <varlistentry>
 422                                 <term><varname>PermissionsStartOnly=</varname></term>
 423                                 <listitem><para>Takes a boolean
 424                                 argument. If true, the permission
 425                                 related execution options as
 426                                 configured with
 427                                 <varname>User=</varname> and similar
 428                                 options (see
 429                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 430                                 for more information) are only applied
 431                                 to the process started with
 432                                 <varname>ExecStart=</varname>, and not
 433                                 to the various other
 434                                 <varname>ExecStartPre=</varname>,
 435                                 <varname>ExecStartPost=</varname>,
 436                                 <varname>ExecReload=</varname>,
 437                                 <varname>ExecStop=</varname>,
 438                                 <varname>ExecStopPost=</varname>
 439                                 commands. If false, the setting is
 440                                 applied to all configured commands the
 441                                 same way. Defaults to
 442                                 false.</para></listitem>
 443                         </varlistentry>
 444
 445                         <varlistentry>
 446                                 <term><varname>RootDirectoryStartOnly=</varname></term>
 447                                 <listitem><para>Takes a boolean
 448                                 argument. If true, the root directory
 449                                 as configured with the
 450                                 <varname>RootDirectory=</varname>
 451                                 option (see
 452                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 453                                 for more information) is only applied
 454                                 to the process started with
 455                                 <varname>ExecStart=</varname>, and not
 456                                 to the various other
 457                                 <varname>ExecStartPre=</varname>,
 458                                 <varname>ExecStartPost=</varname>,
 459                                 <varname>ExecReload=</varname>,
 460                                 <varname>ExecStop=</varname>,
 461                                 <varname>ExecStopPost=</varname>
 462                                 commands. If false, the setting is
 463                                 applied to all configured commands the
 464                                 same way. Defaults to
 465                                 false.</para></listitem>
 466                         </varlistentry>
 467
 468                         <varlistentry>
 469                                 <term><varname>SysVStartPriority=</varname></term>
 470                                 <listitem><para>Set the SysV start
 471                                 priority to use to order this service
 472                                 in relation to SysV services lacking
 473                                 LSB headers. This option is only
 474                                 necessary to fix ordering in relation
 475                                 to legacy SysV services, that have no
 476                                 ordering information encoded in the
 477                                 script headers. As such it should only
 478                                 be used as temporary compatibility
 479                                 option, and not be used in new unit
 480                                 files. Almost always it is a better
 481                                 choice to add explicit ordering
 482                                 directives via
 483                                 <varname>After=</varname> or
 484                                 <varname>Before=</varname>,
 485                                 instead. For more details see
 486                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
 487                                 used, pass an integer value in the
 488                                 range 0-99.</para></listitem>
 489                         </varlistentry>
 490
 491                         <varlistentry>
 492                                 <term><varname>KillMode=</varname></term>
 493                                 <listitem><para>Specifies how
 494                                 processes of this service shall be
 495                                 killed. One of
 496                                 <option>control-group</option>,
 497                                 <option>process-group</option>,
 498                                 <option>process</option>,
 499                                 <option>none</option>.</para>
 500
 501                                 <para>If set to
 502                                 <option>control-group</option> all
 503                                 remaining processes in the control
 504                                 group of this service will be
 505                                 terminated on service stop, after the
 506                                 stop command (as configured with
 507                                 <varname>ExecStop=</varname>) is
 508                                 executed. If set to
 509                                 <option>process-group</option> only
 510                                 the members of the process group of
 511                                 the main service process are
 512                                 killed. If set to
 513                                 <option>process</option> only the main
 514                                 process itself is killed. If set to
 515                                 <option>none</option> no process is
 516                                 killed. In this case only the stop
 517                                 command will be executed on service
 518                                 stop, but no process be killed
 519                                 otherwise. Processes remaining alive
 520                                 after stop are left in their control
 521                                 group and the control group continues
 522                                 to exist after stop unless it is
 523                                 empty. Defaults to
 524                                 <option>control-croup</option>.</para>
 525
 526                                 <para>Processes will first be
 527                                 terminated via SIGTERM. If then after
 528                                 a delay (configured via the
 529                                 <varname>TimeoutSec=</varname> option)
 530                                 processes still remain, the
 531                                 termination request is repeated with
 532                                 the SIGKILL signal. See
 533                                 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 534                                 for more
 535                                 information.</para></listitem>
 536                         </varlistentry>
 537
 538                         <varlistentry>
 539                                 <term><varname>NonBlocking=</varname></term>
 540                                 <listitem><para>Set O_NONBLOCK flag
 541                                 for all file descriptors passed via
 542                                 socket-based activation. If true, all
 543                                 file descriptors >= 3 (i.e. all except
 544                                 STDIN/STDOUT/STDERR) will have
 545                                 the O_NONBLOCK flag set and hence are in
 546                                 non-blocking mode. This option is only
 547                                 useful in conjunction with a socket
 548                                 unit, as described in
 549                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
 550                                 to false.</para></listitem>
 551                         </varlistentry>
 552
 553                         <varlistentry>
 554                                 <term><varname>NotifyAccess=</varname></term>
 555                                 <listitem><para>Controls access to the
 556                                 service status notification socket, as
 557                                 accessible via the
 558                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 559                                 call. Takes one of
 560                                 <option>none</option> (the default),
 561                                 <option>main</option> or
 562                                 <option>all</option>. If
 563                                 <option>none</option> no daemon status
 564                                 updates are accepted by the service
 565                                 processes, all status update messages
 566                                 are ignored. If <option>main</option>
 567                                 only service updates sent from the
 568                                 main process of the service are
 569                                 accepted. If <option>all</option> all
 570                                 services updates from all members of
 571                                 the service's control group are
 572                                 accepted. This option must be set to
 573                                 open access to the notification socket
 574                                 when using
 575                                 <varname>Type=notify</varname> (see above).</para></listitem>
 576                         </varlistentry>
 577
 578                 </variablelist>
 579         </refsect1>
 580
 581         <refsect1>
 582                   <title>See Also</title>
 583                   <para>
 584                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
 585                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 586                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 587                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 588                   </para>
 589         </refsect1>
 590
 591 </refentry>