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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  13   the Free Software Foundation; either version 2 of the License, or
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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         </refsect1>
  92
  93         <refsect1>
  94                 <title>Options</title>
  95
  96                 <para>Service files must include a
  97                 <literal>[Service]</literal> section, which carries
  98                 information about the service and the process it
  99                 supervises. A number of options that may be used in
 100                 this section are shared with other unit types. These
 101                 options are documented in
 102                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
 103                 options specific to the <literal>[Service]</literal>
 104                 section of service units are the following:</para>
 105
 106                 <variablelist>
 107                         <varlistentry>
 108                                 <term><varname>Type=</varname></term>
 109
 110                                 <listitem><para>Configures the process
 111                                 start-up type for this service
 112                                 unit. One of <option>simple</option>,
 113                                 <option>forking</option>,
 114                                 <option>finish</option>,
 115                                 <option>dbus</option>,
 116                                 <option>notify</option>.</para>
 117
 118                                 <para>If set to
 119                                 <option>simple</option> (the default
 120                                 value) it is expected that the process
 121                                 configured with
 122                                 <varname>ExecStart=</varname> is the
 123                                 main process of the service. In this
 124                                 mode, communication channels must be
 125                                 installed before the daemon is started
 126                                 up (e.g. sockets set up by systemd,
 127                                 via socket activation), as systemd
 128                                 will immediately proceed starting
 129                                 follow-up units.</para>
 130
 131                                 <para>If set to
 132                                 <option>forking</option> it is
 133                                 expected that the process configured
 134                                 with <varname>ExecStart=</varname>
 135                                 will start up and call
 136                                 <function>fork()</function>. The
 137                                 parent process is expected to finish
 138                                 when start-up is complete and all
 139                                 communication channels set up. The
 140                                 child continues to run as the main
 141                                 daemon process. This is the behaviour
 142                                 of traditional UNIX daemons. If this
 143                                 setting is used, it is recommended to
 144                                 also use the
 145                                 <varname>PIDFile=</varname> option, so
 146                                 that systemd can identify the main
 147                                 process of the daemon. systemd will
 148                                 proceed starting follow-up units as
 149                                 soon as the parent process
 150                                 exits.</para>
 151
 152                                 <para>Behaviour of
 153                                 <option>finish</option> is similar
 154                                 to <option>simple</option>, however
 155                                 it is expected that the process has to
 156                                 exit before systemd starts follow-up
 157                                 units. <varname>ValidNoProcess=</varname>
 158                                 is particularly useful for this type
 159                                 of service.</para>
 160
 161                                 <para>Behaviour of
 162                                 <option>dbus</option> is similar to
 163                                 <option>simple</option>, however it is
 164                                 expected that the daemon acquires a
 165                                 name on the D-Bus bus, as configured
 166                                 by
 167                                 <varname>BusName=</varname>. systemd
 168                                 will proceed starting follow-up units
 169                                 after the D-Bus bus name has been
 170                                 acquired. Service units with this
 171                                 option configured implicitly have
 172                                 dependencies on the
 173                                 <filename>dbus.target</filename>
 174                                 unit.</para>
 175
 176                                 <para>Behaviour of
 177                                 <option>notify</option> is similar to
 178                                 <option>simple</option>, however it is
 179                                 expected that the daemon sends a
 180                                 notification message via
 181                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 182                                 or an equivalent call when it finished
 183                                 starting up. systemd will proceed
 184                                 starting follow-up units after this
 185                                 notification message has been sent. If
 186                                 this option is used
 187                                 <varname>NotifyAccess=</varname> (see
 188                                 below) must be set to open access to
 189                                 the notification socket provided by
 190                                 systemd. If
 191                                 <varname>NotifyAccess=</varname> is not
 192                                 set, it will be implicitly set to
 193                                 <option>main</option>.</para>
 194                                 </listitem>
 195                         </varlistentry>
 196
 197                         <varlistentry>
 198                                 <term><varname>ValidNoProcess=</varname></term>
 199
 200                                 <listitem><para>Takes a boolean value
 201                                 that specifies whether the service
 202                                 shall be considered active even when
 203                                 all its processes exited. Defaults to
 204                                 <option>no</option>.</para>
 205                                 </listitem>
 206                         </varlistentry>
 207
 208                         <varlistentry>
 209                                 <term><varname>PIDFile=</varname></term>
 210
 211                                 <listitem><para>Takes an absolute file
 212                                 name pointing to the PID file of this
 213                                 daemon. Use of this option is
 214                                 recommended for services where
 215                                 <varname>Type=</varname> is set to
 216                                 <option>forking</option>.</para>
 217                                 </listitem>
 218                         </varlistentry>
 219
 220                         <varlistentry>
 221                                 <term><varname>BusName=</varname></term>
 222
 223                                 <listitem><para>Takes a D-Bus bus
 224                                 name, where this service is reachable
 225                                 as. This option is mandatory for
 226                                 services where
 227                                 <varname>Type=</varname> is set to
 228                                 <option>dbus</option>, but its use
 229                                 is otherwise recommended as well if
 230                                 the process takes a name on the D-Bus
 231                                 bus.</para>
 232                                 </listitem>
 233                         </varlistentry>
 234
 235                         <varlistentry>
 236                                 <term><varname>ExecStart=</varname></term>
 237                                 <listitem><para>Takes a command line
 238                                 that is executed when this service
 239                                 shall be started up. The first token
 240                                 of the command line must be an
 241                                 absolute file name, then followed by
 242                                 arguments for the process. It is
 243                                 mandatory to set this option for all
 244                                 services. This option may not be
 245                                 specified more than once. Optionally,
 246                                 if the absolute file name is prefixed
 247                                 with <literal>@</literal>, the second
 248                                 token will be passed as
 249                                 <literal>argv[0]</literal> to the
 250                                 executed process, followed by the
 251                                 further arguments specified. Unless
 252                                 <varname>Type=forking</varname> is set,
 253                                 the process started via this command
 254                                 line will be considered the main
 255                                 process of the
 256                                 daemon.</para></listitem>
 257                         </varlistentry>
 258
 259                         <varlistentry>
 260                                 <term><varname>ExecStartPre=</varname></term>
 261                                 <term><varname>ExecStartPost=</varname></term>
 262                                 <listitem><para>Additional commands
 263                                 that are executed before (resp. after)
 264                                 the command in
 265                                 <varname>ExecStart=</varname>. If
 266                                 specified more than once, all commands
 267                                 are executed one after the other,
 268                                 serially. Use of these settings is
 269                                 optional.</para></listitem>
 270                         </varlistentry>
 271
 272                         <varlistentry>
 273                                 <term><varname>ExecReload=</varname></term>
 274                                 <listitem><para>Commands to execute to
 275                                 trigger a configuration reload in the
 276                                 service. If used more than once, all
 277                                 commands are executed one after the
 278                                 other, serially. Use of this setting is optional.
 279                                 </para></listitem>
 280                         </varlistentry>
 281
 282                         <varlistentry>
 283                                 <term><varname>ExecStop=</varname></term>
 284                                 <listitem><para>Commands to execute to
 285                                 stop the service started via
 286                                 <varname>ExecStart=</varname>. If used
 287                                 more than once, all commands are
 288                                 executed one after the other,
 289                                 serially. Use of this setting is
 290                                 optional. All processes remaining for
 291                                 a service after the commands
 292                                 configured in this option are run are
 293                                 terminated according to the
 294                                 <varname>KillMode=</varname> setting
 295                                 (see below). If this option is not
 296                                 specified the process is terminated
 297                                 right-away when service stop is
 298                                 requested.</para></listitem>
 299                         </varlistentry>
 300
 301                         <varlistentry>
 302                                 <term><varname>ExecStopPost=</varname></term>
 303                                 <listitem><para>Additional commands
 304                                 that are executed after the service
 305                                 was stopped using the commands
 306                                 configured in
 307                                 <varname>ExecStop=</varname>. If
 308                                 specified more than once, all commands
 309                                 are executed one after the other,
 310                                 serially. Use of these settings is
 311                                 optional.</para></listitem>
 312                         </varlistentry>
 313
 314                         <varlistentry>
 315                                 <term><varname>RestartSec=</varname></term>
 316                                 <listitem><para>Configures the time to
 317                                 sleep before restarting a service (as
 318                                 configured with
 319                                 <varname>Restart=</varname>). Takes a
 320                                 unit-less value in seconds, or a time
 321                                 span value such as "5min
 322                                 20s". Defaults to
 323                                 100ms.</para></listitem>
 324                         </varlistentry>
 325
 326                         <varlistentry>
 327                                 <term><varname>TimeoutSec=</varname></term>
 328                                 <listitem><para>Configures the time to
 329                                 wait for start-up and stop. If a
 330                                 daemon service does not signal
 331                                 start-up completion within the
 332                                 configured time the service will be
 333                                 considered failed and be shut down
 334                                 again. If a service is asked to stop
 335                                 but does not terminate in the
 336                                 specified time it will be terminated
 337                                 forcibly via SIGTERM, and after
 338                                 another delay of this time with
 339                                 SIGKILL. (See
 340                                 <varname>KillMode=</varname>
 341                                 below.) Takes a unit-less value in seconds, or a
 342                                 time span value such as "5min
 343                                 20s". Pass 0 to disable the timeout
 344                                 logic. Defaults to
 345                                 60s.</para></listitem>
 346                         </varlistentry>
 347
 348                         <varlistentry>
 349                                 <term><varname>Restart=</varname></term>
 350                                 <listitem><para>Configures whether the
 351                                 main service process shall be restarted when
 352                                 it exists. Takes one of
 353                                 <option>once</option>,
 354                                 <option>restart-on-success</option> or
 355                                 <option>restart-always</option>. If
 356                                 set to <option>once</option> (the
 357                                 default) the service will not be
 358                                 restarted when it exits. If set to
 359                                 <option>restart-on-success</option> it
 360                                 will be restarted only when it exited
 361                                 cleanly, i.e. terminated with an exit
 362                                 code of 0. If set to
 363                                 <option>restart-always</option> the
 364                                 service will be restarted regardless
 365                                 whether it exited cleanly or not, or
 366                                 got terminated abnormally by a
 367                                 signal.</para></listitem>
 368                         </varlistentry>
 369
 370                         <varlistentry>
 371                                 <term><varname>PermissionsStartOnly=</varname></term>
 372                                 <listitem><para>Takes a boolean
 373                                 argument. If true, the permission
 374                                 related execution options as
 375                                 configured with
 376                                 <varname>User=</varname> and similar
 377                                 options (see
 378                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 379                                 for more information) are only applied
 380                                 to the process started with
 381                                 <varname>ExecStart=</varname>, and not
 382                                 to the various other
 383                                 <varname>ExecStartPre=</varname>,
 384                                 <varname>ExecStartPost=</varname>,
 385                                 <varname>ExecReload=</varname>,
 386                                 <varname>ExecStop=</varname>,
 387                                 <varname>ExecStopPost=</varname>
 388                                 commands. If false, the setting is
 389                                 applied to all configured commands the
 390                                 same way. Defaults to
 391                                 false.</para></listitem>
 392                         </varlistentry>
 393
 394                         <varlistentry>
 395                                 <term><varname>RootDirectoryStartOnly=</varname></term>
 396                                 <listitem><para>Takes a boolean
 397                                 argument. If true, the root directory
 398                                 as configured with the
 399                                 <varname>RootDirectory=</varname>
 400                                 option (see
 401                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 402                                 for more information) is only applied
 403                                 to the process started with
 404                                 <varname>ExecStart=</varname>, and not
 405                                 to the various other
 406                                 <varname>ExecStartPre=</varname>,
 407                                 <varname>ExecStartPost=</varname>,
 408                                 <varname>ExecReload=</varname>,
 409                                 <varname>ExecStop=</varname>,
 410                                 <varname>ExecStopPost=</varname>
 411                                 commands. If false, the setting is
 412                                 applied to all configured commands the
 413                                 same way. Defaults to
 414                                 false.</para></listitem>
 415                         </varlistentry>
 416
 417                         <varlistentry>
 418                                 <term><varname>SysVStartPriority=</varname></term>
 419                                 <listitem><para>Set the SysV start
 420                                 priority to use to order this service
 421                                 in relation to SysV services lacking
 422                                 LSB headers. This option is only
 423                                 necessary to fix ordering in relation
 424                                 to legacy SysV services, that have no
 425                                 ordering information encoded in the
 426                                 script headers. As such it should only
 427                                 be used as temporary compatibility
 428                                 option, and not be used in new unit
 429                                 files. Almost always it is a better
 430                                 choice to add explicit ordering
 431                                 directives via
 432                                 <varname>After=</varname> or
 433                                 <varname>Before=</varname>,
 434                                 instead. For more details see
 435                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
 436                                 used, pass an integer value in the
 437                                 range 0-99.</para></listitem>
 438                         </varlistentry>
 439
 440                         <varlistentry>
 441                                 <term><varname>KillMode=</varname></term>
 442                                 <listitem><para>Specifies how
 443                                 processes of this service shall be
 444                                 killed. One of
 445                                 <option>control-group</option>,
 446                                 <option>process-group</option>,
 447                                 <option>process</option>,
 448                                 <option>none</option>.</para>
 449
 450                                 <para>If set to
 451                                 <option>control-group</option> all
 452                                 remaining processes in the control
 453                                 group of this service will be
 454                                 terminated on service stop, after the
 455                                 stop command (as configured with
 456                                 <varname>ExecStop=</varname>) is
 457                                 executed. If set to
 458                                 <option>process-group</option> only
 459                                 the members of the process group of
 460                                 the main service process are
 461                                 killed. If set to
 462                                 <option>process</option> only the main
 463                                 process itself is killed. If set to
 464                                 <option>none</option> no process is
 465                                 killed. In this case only the stop
 466                                 command will be executed on service
 467                                 stop, but no process be killed
 468                                 otherwise. Processes remaining alive
 469                                 after stop are left in their control
 470                                 group and the control group continues
 471                                 to exist after stop unless it is
 472                                 empty. Defaults to
 473                                 <option>control-croup</option>.</para>
 474
 475                                 <para>Processes will first be
 476                                 terminated via SIGTERM. If then after
 477                                 a delay (configured via the
 478                                 <varname>TimeoutSec=</varname> option)
 479                                 processes still remain, the
 480                                 termination request is repeated with
 481                                 the SIGKILL signal. See
 482                                 <citerefentry><refentrytitle>kill</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 483                                 for more
 484                                 information.</para></listitem>
 485                         </varlistentry>
 486
 487                         <varlistentry>
 488                                 <term><varname>NonBlocking=</varname></term>
 489                                 <listitem><para>Set O_NONBLOCK flag
 490                                 for all file descriptors passed via
 491                                 socket-based activation. If true, all
 492                                 file descriptors >= 3 (i.e. all except
 493                                 STDIN/STDOUT/STDERR) will have
 494                                 the O_NONBLOCK flag set and hence are in
 495                                 non-blocking mode. This option is only
 496                                 useful in conjunction with a socket
 497                                 unit, as described in
 498                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
 499                                 to false.</para></listitem>
 500                         </varlistentry>
 501
 502                         <varlistentry>
 503                                 <term><varname>NotifyAccess=</varname></term>
 504                                 <listitem><para>Controls access to the
 505                                 service status notification socket, as
 506                                 accessible via the
 507                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 508                                 call. Takes one of
 509                                 <option>none</option> (the default),
 510                                 <option>main</option> or
 511                                 <option>all</option>. If
 512                                 <option>none</option> no daemon status
 513                                 updates are accepted by the service
 514                                 processes, all status update messages
 515                                 are ignored. If <option>main</option>
 516                                 only service updates sent from the
 517                                 main process of the service are
 518                                 accepted. If <option>all</option> all
 519                                 services updates from all members of
 520                                 the service's control group are
 521                                 accepted. This option must be set to
 522                                 open access to the notification socket
 523                                 when using
 524                                 <varname>Type=notify</varname> (see above).</para></listitem>
 525                         </varlistentry>
 526
 527                 </variablelist>
 528         </refsect1>
 529
 530         <refsect1>
 531                   <title>See Also</title>
 532                   <para>
 533                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 534                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
 535                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 536                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 537                   </para>
 538         </refsect1>
 539
 540 </refentry>