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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  12   under the terms of the GNU Lesser General Public License as published by
  13   the Free Software Foundation; either version 2.1 of the License, or
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  19   Lesser General Public License for more details.
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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>Service unit configuration</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <para><filename><replaceable>service</replaceable>.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, and in
  76                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  77                 which define the way the processes of the service are
  78                 terminated, and in
  79                 <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
  80                 which configure resource control settings for the
  81                 processes of the service.</para>
  82
  83                 <para>Unless <varname>DefaultDependencies=</varname>
  84                 is set to <option>false</option>, service units will
  85                 implicitly have dependencies of type
  86                 <varname>Requires=</varname> and
  87                 <varname>After=</varname> on
  88                 <filename>basic.target</filename> as well as
  89                 dependencies of type <varname>Conflicts=</varname> and
  90                 <varname>Before=</varname> on
  91                 <filename>shutdown.target</filename>. These ensure
  92                 that normal service units pull in basic system
  93                 initialization, and are terminated cleanly prior to
  94                 system shutdown. Only services involved with early
  95                 boot or late system shutdown should disable this
  96                 option.</para>
  97
  98                 <para>If a service is requested under a certain name
  99                 but no unit configuration file is found, systemd looks
 100                 for a SysV init script by the same name (with the
 101                 <filename>.service</filename> suffix removed) and
 102                 dynamically creates a service unit from that
 103                 script. This is useful for compatibility with
 104                 SysV. Note that this compatibility is quite
 105                 comprehensive but not 100%. For details about the
 106                 incompatibilities see the <ulink
 107                 url="http://www.freedesktop.org/wiki/Software/systemd/Incompatibilities">Incompatibilities
 108                 with SysV</ulink> document.
 109                 </para>
 110         </refsect1>
 111
 112         <refsect1>
 113                 <title>Options</title>
 114
 115                 <para>Service files must include a
 116                 <literal>[Service]</literal> section, which carries
 117                 information about the service and the process it
 118                 supervises. A number of options that may be used in
 119                 this section are shared with other unit types. These
 120                 options are documented in
 121                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 122                 and
 123                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
 124                 options specific to the <literal>[Service]</literal>
 125                 section of service units are the following:</para>
 126
 127                 <variablelist class='unit-directives'>
 128                         <varlistentry>
 129                                 <term><varname>Type=</varname></term>
 130
 131                                 <listitem><para>Configures the process
 132                                 start-up type for this service
 133                                 unit. One of <option>simple</option>,
 134                                 <option>forking</option>,
 135                                 <option>oneshot</option>,
 136                                 <option>dbus</option>,
 137                                 <option>notify</option> or
 138                                 <option>idle</option>.</para>
 139
 140                                 <para>If set to
 141                                 <option>simple</option> (the default
 142                                 value if neither
 143                                 <varname>Type=</varname> nor
 144                                 <varname>BusName=</varname> are
 145                                 specified), it is expected that the
 146                                 process configured with
 147                                 <varname>ExecStart=</varname> is the
 148                                 main process of the service. In this
 149                                 mode, if the process offers
 150                                 functionality to other processes on
 151                                 the system, its communication channels
 152                                 should be installed before the daemon
 153                                 is started up (e.g. sockets set up by
 154                                 systemd, via socket activation), as
 155                                 systemd will immediately proceed
 156                                 starting follow-up units.</para>
 157
 158                                 <para>If set to
 159                                 <option>forking</option>, it is
 160                                 expected that the process configured
 161                                 with <varname>ExecStart=</varname>
 162                                 will call <function>fork()</function>
 163                                 as part of its start-up. The parent process is
 164                                 expected to exit when start-up is
 165                                 complete and all communication
 166                                 channels are set up. The child continues
 167                                 to run as the main daemon
 168                                 process. This is the behavior of
 169                                 traditional UNIX daemons. If this
 170                                 setting is used, it is recommended to
 171                                 also use the
 172                                 <varname>PIDFile=</varname> option, so
 173                                 that systemd can identify the main
 174                                 process of the daemon. systemd will
 175                                 proceed starting follow-up units as
 176                                 soon as the parent process
 177                                 exits.</para>
 178
 179                                 <para>Behavior of
 180                                 <option>oneshot</option> is similar
 181                                 to <option>simple</option>, however
 182                                 it is expected that the process has to
 183                                 exit before systemd starts follow-up
 184                                 units. <varname>RemainAfterExit=</varname>
 185                                 is particularly useful for this type
 186                                 of service.</para>
 187
 188                                 <para>Behavior of
 189                                 <option>dbus</option> is similar to
 190                                 <option>simple</option>, however it is
 191                                 expected that the daemon acquires a
 192                                 name on the D-Bus bus, as configured
 193                                 by
 194                                 <varname>BusName=</varname>. systemd
 195                                 will proceed starting follow-up units
 196                                 after the D-Bus bus name has been
 197                                 acquired. Service units with this
 198                                 option configured implicitly gain
 199                                 dependencies on the
 200                                 <filename>dbus.socket</filename>
 201                                 unit. This type is the default if
 202                                 <varname>BusName=</varname> is
 203                                 specified.</para>
 204
 205                                 <para>Behavior of
 206                                 <option>notify</option> is similar to
 207                                 <option>simple</option>, however it is
 208                                 expected that the daemon sends a
 209                                 notification message via
 210                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 211                                 or an equivalent call when it finished
 212                                 starting up. systemd will proceed
 213                                 starting follow-up units after this
 214                                 notification message has been sent. If
 215                                 this option is used,
 216                                 <varname>NotifyAccess=</varname> (see
 217                                 below) should be set to open access to
 218                                 the notification socket provided by
 219                                 systemd. If
 220                                 <varname>NotifyAccess=</varname> is
 221                                 not set, it will be implicitly set to
 222                                 <option>main</option>. Note that
 223                                 currently
 224                                 <varname>Type=</varname><option>notify</option>
 225                                 will not work if used in combination with
 226                                 <varname>PrivateNetwork=</varname><option>yes</option>.</para>
 227
 228                                 <para>Behavior of
 229                                 <option>idle</option> is very similar
 230                                 to <option>simple</option>, however
 231                                 actual execution of the service
 232                                 binary is delayed until all jobs are
 233                                 dispatched. This may be used to avoid
 234                                 interleaving of output of shell
 235                                 services with the status output on the
 236                                 console.</para>
 237                                 </listitem>
 238                         </varlistentry>
 239
 240                         <varlistentry>
 241                                 <term><varname>RemainAfterExit=</varname></term>
 242
 243                                 <listitem><para>Takes a boolean value
 244                                 that specifies whether the service
 245                                 shall be considered active even when
 246                                 all its processes exited. Defaults to
 247                                 <option>no</option>.</para>
 248                                 </listitem>
 249                         </varlistentry>
 250
 251                         <varlistentry>
 252                                 <term><varname>GuessMainPID=</varname></term>
 253
 254                                 <listitem><para>Takes a boolean value
 255                                 that specifies whether systemd should
 256                                 try to guess the main PID of a service
 257                                 if it cannot be determined
 258                                 reliably. This option is ignored
 259                                 unless <option>Type=forking</option>
 260                                 is set and <option>PIDFile=</option>
 261                                 is unset because for the other types
 262                                 or with an explicitly configured PID
 263                                 file the main PID is always known. The
 264                                 guessing algorithm might come to
 265                                 incorrect conclusions if a daemon
 266                                 consists of more than one process. If
 267                                 the main PID cannot be determined,
 268                                 failure detection and automatic
 269                                 restarting of a service will not work
 270                                 reliably. Defaults to
 271                                 <option>yes</option>.</para>
 272                                 </listitem>
 273                         </varlistentry>
 274
 275                         <varlistentry>
 276                                 <term><varname>PIDFile=</varname></term>
 277
 278                                 <listitem><para>Takes an absolute file
 279                                 name pointing to the PID file of this
 280                                 daemon. Use of this option is
 281                                 recommended for services where
 282                                 <varname>Type=</varname> is set to
 283                                 <option>forking</option>. systemd will
 284                                 read the PID of the main process of
 285                                 the daemon after start-up of the
 286                                 service. systemd will not write to the
 287                                 file configured here.</para>
 288                                 </listitem>
 289                         </varlistentry>
 290
 291                         <varlistentry>
 292                                 <term><varname>BusName=</varname></term>
 293
 294                                 <listitem><para>Takes a D-Bus bus
 295                                 name, that this service is reachable
 296                                 as. This option is mandatory for
 297                                 services where
 298                                 <varname>Type=</varname> is set to
 299                                 <option>dbus</option>, but its use
 300                                 is otherwise recommended as well if
 301                                 the process takes a name on the D-Bus
 302                                 bus.</para>
 303                                 </listitem>
 304                         </varlistentry>
 305
 306                         <varlistentry>
 307                                 <term><varname>ExecStart=</varname></term>
 308                                 <listitem><para>Commands with their
 309                                 arguments that are executed when this
 310                                 service is started. For each of the
 311                                 specified commands, the first argument
 312                                 must be an absolute and literal path
 313                                 to an executable.</para>
 314
 315                                 <para>When <varname>Type</varname> is
 316                                 not <option>oneshot</option>, only one
 317                                 command may be given. When
 318                                 <varname>Type=oneshot</varname> is
 319                                 used, more than one command may be
 320                                 specified. Multiple command lines may
 321                                 be concatenated in a single directive,
 322                                 by separating them with semicolons
 323                                 (these semicolons must be passed as
 324                                 separate words). Alternatively, this
 325                                 directive may be specified more than
 326                                 once with the same effect.
 327                                 Lone semicolons may be escaped as
 328                                 <literal>\;</literal>. If the empty
 329                                 string is assigned to this option, the
 330                                 list of commands to start is reset,
 331                                 prior assignments of this option will
 332                                 have no effect.</para>
 333
 334                                 <para>Each command line is split on
 335                                 whitespace, with the first item being
 336                                 the command to execute, and the
 337                                 subsequent items being the arguments.
 338                                 Double quotes ("...") and single
 339                                 quotes ('...') may be used, in which
 340                                 case everything until the next
 341                                 matching quote becomes part of the
 342                                 same argument. Quotes themselves are
 343                                 removed after parsing. In addition, a
 344                                 trailing backslash
 345                                 (<literal>\</literal>) may be used to
 346                                 merge lines. This syntax is intended
 347                                 to be very similar to shell syntax,
 348                                 but only the meta-characters and
 349                                 expansions described in the following
 350                                 paragraphs are understood.
 351                                 Specifically, redirection using
 352                                 <literal>&lt;</literal>,
 353                                 <literal>&lt;&lt;</literal>,
 354                                 <literal>&gt;</literal>, and
 355                                 <literal>&gt;&gt;</literal>, pipes
 356                                 using <literal>|</literal>, and
 357                                 running programs in the background
 358                                 using <literal>&amp;</literal>
 359                                 and <emphasis>other elements of shell
 360                                 syntax are not supported</emphasis>.
 361                                 </para>
 362
 363                                 <para>If more than one command is
 364                                 specified, the commands are invoked
 365                                 one by one sequentially in the order
 366                                 they appear in the unit file. If one
 367                                 of the commands fails (and is not
 368                                 prefixed with <literal>-</literal>),
 369                                 other lines are not executed and the
 370                                 unit is considered failed.</para>
 371
 372                                 <para>Unless
 373                                 <varname>Type=forking</varname> is
 374                                 set, the process started via this
 375                                 command line will be considered the
 376                                 main process of the daemon.</para>
 377
 378                                 <para>The command line accepts
 379                                 <literal>%</literal> specifiers as
 380                                 described in
 381                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 382                                 Note that the first argument of the
 383                                 command line (i.e. the program to
 384                                 execute) may not include
 385                                 specifiers.</para>
 386
 387                                 <para>Basic environment variable
 388                                 substitution is supported. Use
 389                                 <literal>${FOO}</literal> as part of a
 390                                 word, or as a word of its own on the
 391                                 command line, in which case it will be
 392                                 replaced by the value of the
 393                                 environment variable including all
 394                                 whitespace it contains, resulting in a
 395                                 single argument. Use
 396                                 <literal>$FOO</literal> as a separate
 397                                 word on the command line, in which
 398                                 case it will be replaced by the value
 399                                 of the environment variable split at
 400                                 whitespace, resulting in zero or more
 401                                 arguments. To pass a literal dollar
 402                                 sign, use <literal>$$</literal>.
 403                                 Variables whose value is not known at
 404                                 expansion time are treated as empty
 405                                 strings. Note that the first argument
 406                                 (i.e. the program to execute) may not
 407                                 be a variable.</para>
 408
 409                                 <para>Variables to be used in this
 410                                 fashion may be defined through
 411                                 <varname>Environment=</varname> and
 412                                 <varname>EnvironmentFile=</varname>.
 413                                 In addition, variables listed in
 414                                 section "Environment variables in
 415                                 spawned processes" in
 416                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 417                                 which are considered "static
 418                                 configuration" may used (this includes
 419                                 e.g. <varname>$USER</varname>, but not
 420                                 <varname>$TERM</varname>).</para>
 421
 422                                 <para>Optionally, if the absolute file
 423                                 name is prefixed with
 424                                 <literal>@</literal>, the second token
 425                                 will be passed as
 426                                 <literal>argv[0]</literal> to the
 427                                 executed process, followed by the
 428                                 further arguments specified. If the
 429                                 absolute filename is prefixed with
 430                                 <literal>-</literal>, an exit code of
 431                                 the command normally considered a
 432                                 failure (i.e. non-zero exit status or
 433                                 abnormal exit due to signal) is ignored
 434                                 and considered success. If both
 435                                 <literal>-</literal> and
 436                                 <literal>@</literal> are used, they
 437                                 can appear in either order.</para>
 438
 439                                 <para>Note that this setting does not
 440                                 directly support shell command
 441                                 lines. If shell command lines are to
 442                                 be used, they need to be passed
 443                                 explicitly to a shell implementation
 444                                 of some kind. Example:</para>
 445                                 <programlisting>ExecStart=/bin/sh -c 'dmesg | tac'</programlisting>
 446                                 <para>Example:</para>
 447                                 <programlisting>ExecStart=/bin/echo one ; /bin/echo "two two"</programlisting>
 448                                 <para>This will execute
 449                                 <command>/bin/echo</command> two
 450                                 times, each time with one argument,
 451                                 <literal>one</literal> and
 452                                 <literal>two two</literal>,
 453                                 respectively. Since two commands are
 454                                 specified,
 455                                 <varname>Type=oneshot</varname> must
 456                                 be used.</para>
 457
 458                                 <para>Example:</para>
 459                                 <programlisting>ExecStart=/bin/echo / &gt;/dev/null &amp; \; \
 460 /bin/ls</programlisting>
 461                                 <para>This will execute
 462                                 <command>/bin/echo</command> with five
 463                                 arguments: <literal>/</literal>,
 464                                 <literal>&gt;/dev/null</literal>,
 465                                 <literal>&amp;</literal>,
 466                                 <literal>;</literal>, and
 467                                 <literal>/bin/ls</literal>.</para>
 468
 469                                 <para>Example:</para>
 470                                 <programlisting>Environment="ONE=one" 'TWO=two two'
 471 ExecStart=/bin/echo $ONE $TWO ${TWO}</programlisting>
 472                                 <para>This will execute
 473                                 <command>/bin/echo</command> with four
 474                                 arguments: <literal>one</literal>,
 475                                 <literal>two</literal>,
 476                                 <literal>two</literal>, and
 477                                 <literal>two two</literal>.</para>
 478                               </listitem>
 479                         </varlistentry>
 480
 481                         <varlistentry>
 482                                 <term><varname>ExecStartPre=</varname></term>
 483                                 <term><varname>ExecStartPost=</varname></term>
 484                                 <listitem><para>Additional commands
 485                                 that are executed before or after
 486                                 the command in
 487                                 <varname>ExecStart=</varname>, respectively.
 488                                 Syntax is the same as for
 489                                 <varname>ExecStart=</varname>, except
 490                                 that multiple command lines are allowed
 491                                 and the commands are executed one
 492                                 after the other, serially.</para>
 493
 494                                 <para>If any of those commands (not
 495                                 prefixed with <literal>-</literal>)
 496                                 fail, the rest are not executed and
 497                                 the unit is considered failed.</para>
 498                                 </listitem>
 499                         </varlistentry>
 500
 501                         <varlistentry>
 502                                 <term><varname>ExecReload=</varname></term>
 503                                 <listitem><para>Commands to execute to
 504                                 trigger a configuration reload in the
 505                                 service. This argument takes multiple
 506                                 command lines, following the same
 507                                 scheme as described for
 508                                 <varname>ExecStart=</varname>
 509                                 above. Use of this setting is
 510                                 optional. Specifier and environment
 511                                 variable substitution is supported
 512                                 here following the same scheme as for
 513                                 <varname>ExecStart=</varname>.</para>
 514
 515                                 <para>One additional special
 516                                 environment variables is set: if known
 517                                 <varname>$MAINPID</varname> is set to
 518                                 the main process of the daemon, and
 519                                 may be used for command lines like the
 520                                 following:</para>
 521
 522                                 <programlisting>/bin/kill -HUP $MAINPID</programlisting>
 523                                 </listitem>
 524                         </varlistentry>
 525
 526                         <varlistentry>
 527                                 <term><varname>ExecStop=</varname></term>
 528                                 <listitem><para>Commands to execute to
 529                                 stop the service started via
 530                                 <varname>ExecStart=</varname>. This
 531                                 argument takes multiple command lines,
 532                                 following the same scheme as described
 533                                 for <varname>ExecStart=</varname>
 534                                 above. Use of this setting is
 535                                 optional. All processes remaining for
 536                                 a service after the commands
 537                                 configured in this option are run are
 538                                 terminated according to the
 539                                 <varname>KillMode=</varname> setting
 540                                 (see
 541                                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>). If
 542                                 this option is not specified, the
 543                                 process is terminated right-away when
 544                                 service stop is requested. Specifier
 545                                 and environment variable substitution
 546                                 is supported (including
 547                                 <varname>$MAINPID</varname>, see
 548                                 above).</para></listitem>
 549                         </varlistentry>
 550
 551                         <varlistentry>
 552                                 <term><varname>ExecStopPost=</varname></term>
 553                                 <listitem><para>Additional commands
 554                                 that are executed after the service
 555                                 was stopped. This includes cases where
 556                                 the commands configured in
 557                                 <varname>ExecStop=</varname> were used,
 558                                 where the service does not have any
 559                                 <varname>ExecStop=</varname> defined, or
 560                                 where the service exited unexpectedly. This
 561                                 argument takes multiple command lines,
 562                                 following the same scheme as described
 563                                 for <varname>ExecStart</varname>. Use
 564                                 of these settings is
 565                                 optional. Specifier and environment
 566                                 variable substitution is
 567                                 supported.</para></listitem>
 568                         </varlistentry>
 569
 570                         <varlistentry>
 571                                 <term><varname>RestartSec=</varname></term>
 572                                 <listitem><para>Configures the time to
 573                                 sleep before restarting a service (as
 574                                 configured with
 575                                 <varname>Restart=</varname>). Takes a
 576                                 unit-less value in seconds, or a time
 577                                 span value such as "5min
 578                                 20s". Defaults to
 579                                 100ms.</para></listitem>
 580                         </varlistentry>
 581
 582                         <varlistentry>
 583                                 <term><varname>TimeoutStartSec=</varname></term>
 584                                 <listitem><para>Configures the time to
 585                                 wait for start-up. If a
 586                                 daemon service does not signal
 587                                 start-up completion within the
 588                                 configured time, the service will be
 589                                 considered failed and be shut down
 590                                 again.
 591                                 Takes a unit-less value in seconds, or a
 592                                 time span value such as "5min
 593                                 20s". Pass 0 to disable the timeout
 594                                 logic. Defaults to <varname>TimeoutStartSec=</varname> from the
 595                                 manager configuration file, except when
 596                                 <varname>Type=oneshot</varname> is
 597                                 used, in which case the timeout
 598                                 is disabled by default.
 599                                 </para></listitem>
 600                         </varlistentry>
 601
 602                         <varlistentry>
 603                                 <term><varname>TimeoutStopSec=</varname></term>
 604                                 <listitem><para>Configures the time to
 605                                 wait for stop. If a service is asked
 606                                 to stop but does not terminate in the
 607                                 specified time, it will be terminated
 608                                 forcibly via <constant>SIGTERM</constant>, and after
 609                                 another delay of this time with
 610                                 <constant>SIGKILL</constant> (See
 611                                 <varname>KillMode=</varname>
 612                                 in <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
 613                                 Takes a unit-less value in seconds, or a
 614                                 time span value such as "5min
 615                                 20s". Pass 0 to disable the timeout
 616                                 logic. Defaults to <varname>TimeoutStartSec=</varname> from the
 617                                 manager configuration file.
 618                                 </para></listitem>
 619                         </varlistentry>
 620
 621                         <varlistentry>
 622                                 <term><varname>TimeoutSec=</varname></term>
 623                                 <listitem><para>A shorthand for configuring
 624                                 both <varname>TimeoutStartSec=</varname>
 625                                 and <varname>TimeoutStopSec=</varname>
 626                                 to the specified value.
 627                                 </para></listitem>
 628                         </varlistentry>
 629
 630                         <varlistentry>
 631                                 <term><varname>WatchdogSec=</varname></term>
 632                                 <listitem><para>Configures the
 633                                 watchdog timeout for a service. The
 634                                 watchdog is activated when the start-up is
 635                                 completed. The service must call
 636                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 637                                 regularly with "WATCHDOG=1" (i.e. the
 638                                 "keep-alive ping"). If the time
 639                                 between two such calls is larger than
 640                                 the configured time, then the service
 641                                 is placed in a failure state. By
 642                                 setting <varname>Restart=</varname> to
 643                                 <option>on-failure</option> or
 644                                 <option>always</option>, the service
 645                                 will be automatically restarted. The
 646                                 time configured here will be passed to
 647                                 the executed service process in the
 648                                 <varname>WATCHDOG_USEC=</varname>
 649                                 environment variable. This allows
 650                                 daemons to automatically enable the
 651                                 keep-alive pinging logic if watchdog
 652                                 support is enabled for the service. If
 653                                 this option is used,
 654                                 <varname>NotifyAccess=</varname> (see
 655                                 below) should be set to open access to
 656                                 the notification socket provided by
 657                                 systemd. If
 658                                 <varname>NotifyAccess=</varname> is
 659                                 not set, it will be implicitly set to
 660                                 <option>main</option>. Defaults to 0,
 661                                 which disables this
 662                                 feature.</para></listitem>
 663                         </varlistentry>
 664
 665                         <varlistentry>
 666                                 <term><varname>Restart=</varname></term>
 667                                 <listitem><para>Configures whether the
 668                                 service shall be restarted when the
 669                                 service process exits, is killed,
 670                                 or a timeout is reached. The service
 671                                 process may be the main service
 672                                 process, but also one of the processes
 673                                 specified with
 674                                 <varname>ExecStartPre=</varname>,
 675                                 <varname>ExecStartPost=</varname>,
 676                                 <varname>ExecStopPre=</varname>,
 677                                 <varname>ExecStopPost=</varname>, or
 678                                 <varname>ExecReload=</varname>.
 679                                 When the death of the process is a
 680                                 result of systemd operation (e.g. service
 681                                 stop or restart), the service will not be
 682                                 restarted. Timeouts include missing
 683                                 the watchdog "keep-alive ping"
 684                                 deadline and a service start, reload,
 685                                 and stop operation timeouts.</para>
 686
 687                                 <para>Takes one of
 688                                 <option>no</option>,
 689                                 <option>on-success</option>,
 690                                 <option>on-failure</option>,
 691                                 <option>on-watchdog</option>,
 692                                 <option>on-abort</option>, or
 693                                 <option>always</option>. If set to
 694                                 <option>no</option> (the default), the
 695                                 service will not be restarted. If set to
 696                                 <option>on-success</option>, it will be
 697                                 restarted only when the service process
 698                                 exits cleanly.
 699                                 In this context, a clean exit means
 700                                 an exit code of 0, or one of the signals
 701                                 <constant>SIGHUP</constant>, <constant>SIGINT</constant>, <constant>SIGTERM</constant>, or <constant>SIGPIPE</constant>, and
 702                                 additionally, exit statuses and signals
 703                                 specified in <varname>SuccessExitStatus=</varname>.
 704                                 If set to <option>on-failure</option>,
 705                                 the service will be restarted when the
 706                                 process exits with an nonzero exit code,
 707                                 is terminated by a signal (including on
 708                                 core dump), when an operation (such as
 709                                 service reload) times out, and when the
 710                                 configured watchdog timeout is triggered.
 711                                 If set to
 712                                 <option>on-abort</option>, the service
 713                                 will be restarted only if the service
 714                                 process exits due to an uncaught
 715                                 signal not specified as a clean exit
 716                                 status.
 717                                 If set to
 718                                 <option>on-watchdog</option>, the service
 719                                 will be restarted only if the watchdog
 720                                 timeout for the service expires.
 721                                 If set to
 722                                 <option>always</option>, the service
 723                                 will be restarted regardless of whether
 724                                 it exited cleanly or not, got
 725                                 terminated abnormally by a signal or
 726                                 hit a timeout.</para>
 727
 728                                 <para>In addition to the above settings,
 729                                 the service will not be restarted if the
 730                                 exit code or signal is specified in
 731                                 <varname>RestartPreventExitStatus=</varname>
 732                                 (see below).</para></listitem>
 733                         </varlistentry>
 734
 735                         <varlistentry>
 736                                 <term><varname>SuccessExitStatus=</varname></term>
 737                                 <listitem><para>Takes a list of exit
 738                                 status definitions that when returned
 739                                 by the main service process will be
 740                                 considered successful termination, in
 741                                 addition to the normal successful exit
 742                                 code 0 and the signals <constant>SIGHUP</constant>, <constant>SIGINT</constant>,
 743                                 <constant>SIGTERM</constant>, and <constant>SIGPIPE</constant>. Exit status
 744                                 definitions can either be numeric exit
 745                                 codes or termination signal names,
 746                                 separated by spaces. Signals will only
 747                                 be considered if the service does not implement
 748                                 a signal handler and exits as a direct result
 749                                 of receiving the signal. For example:
 750                                 <programlisting>SuccessExitStatus=1 2 8 <constant>SIGKILL</constant></programlisting>
 751                                 ensures that exit codes 1, 2, 8 and
 752                                 the termination signal
 753                                 <constant>SIGKILL</constant> are
 754                                 considered clean service terminations.
 755                                 </para>
 756
 757                                 <para>Note that if a process has a
 758                                 signal handler installed and exits by
 759                                 calling
 760                                 <citerefentry><refentrytitle>_exit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 761                                 in response to a signal, the
 762                                 information about the signal is lost.
 763                                 Programs should instead perform cleanup and kill themselves with the same signal instead. See
 764                                 <ulink url="http://www.cons.org/cracauer/sigint.html">Proper handling of SIGINT/SIGQUIT — How to be a proper program</ulink>.</para>
 765
 766                                 <para>This option may appear more than once
 767                                 in which case the list of successful
 768                                 exit statuses is merged. If the empty
 769                                 string is assigned to this option, the
 770                                 list is reset, all prior assignments
 771                                 of this option will have no
 772                                 effect.</para></listitem>
 773                         </varlistentry>
 774
 775                         <varlistentry>
 776                                 <term><varname>RestartPreventExitStatus=</varname></term>
 777                                 <listitem><para>Takes a list of exit
 778                                 status definitions that when returned
 779                                 by the main service process will
 780                                 prevent automatic service restarts
 781                                 regardless of the restart setting
 782                                 configured with
 783                                 <varname>Restart=</varname>. Exit
 784                                 status definitions can either be
 785                                 numeric exit codes or termination
 786                                 signal names, and are separated by
 787                                 spaces. Defaults to the empty list, so
 788                                 that by default no exit status is
 789                                 excluded from the configured restart
 790                                 logic. Example:
 791                                 <literal>RestartPreventExitStatus=1 6
 792                                 SIGABRT</literal>, ensures that exit
 793                                 codes 1 and 6 and the termination
 794                                 signal SIGABRT will not result in
 795                                 automatic service restarting. This
 796                                 option may appear more than once in
 797                                 which case the list of restart preventing
 798                                 statuses is merged. If the empty
 799                                 string is assigned to this option, the
 800                                 list is reset, all prior assignments
 801                                 of this option will have no
 802                                 effect.</para></listitem>
 803                         </varlistentry>
 804
 805                         <varlistentry>
 806                                 <term><varname>PermissionsStartOnly=</varname></term>
 807                                 <listitem><para>Takes a boolean
 808                                 argument. If true, the permission
 809                                 related execution options as
 810                                 configured with
 811                                 <varname>User=</varname> and similar
 812                                 options (see
 813                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 814                                 for more information) are only applied
 815                                 to the process started with
 816                                 <varname>ExecStart=</varname>, and not
 817                                 to the various other
 818                                 <varname>ExecStartPre=</varname>,
 819                                 <varname>ExecStartPost=</varname>,
 820                                 <varname>ExecReload=</varname>,
 821                                 <varname>ExecStop=</varname>,
 822                                 <varname>ExecStopPost=</varname>
 823                                 commands. If false, the setting is
 824                                 applied to all configured commands the
 825                                 same way. Defaults to
 826                                 false.</para></listitem>
 827                         </varlistentry>
 828
 829                         <varlistentry>
 830                                 <term><varname>RootDirectoryStartOnly=</varname></term>
 831                                 <listitem><para>Takes a boolean
 832                                 argument. If true, the root directory
 833                                 as configured with the
 834                                 <varname>RootDirectory=</varname>
 835                                 option (see
 836                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 837                                 for more information) is only applied
 838                                 to the process started with
 839                                 <varname>ExecStart=</varname>, and not
 840                                 to the various other
 841                                 <varname>ExecStartPre=</varname>,
 842                                 <varname>ExecStartPost=</varname>,
 843                                 <varname>ExecReload=</varname>,
 844                                 <varname>ExecStop=</varname>,
 845                                 <varname>ExecStopPost=</varname>
 846                                 commands. If false, the setting is
 847                                 applied to all configured commands the
 848                                 same way. Defaults to
 849                                 false.</para></listitem>
 850                         </varlistentry>
 851
 852                         <varlistentry>
 853                                 <term><varname>NonBlocking=</varname></term>
 854                                 <listitem><para>Set O_NONBLOCK flag
 855                                 for all file descriptors passed via
 856                                 socket-based activation. If true, all
 857                                 file descriptors >= 3 (i.e. all except
 858                                 STDIN/STDOUT/STDERR) will have
 859                                 the O_NONBLOCK flag set and hence are in
 860                                 non-blocking mode. This option is only
 861                                 useful in conjunction with a socket
 862                                 unit, as described in
 863                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
 864                                 to false.</para></listitem>
 865                         </varlistentry>
 866
 867                         <varlistentry>
 868                                 <term><varname>NotifyAccess=</varname></term>
 869                                 <listitem><para>Controls access to the
 870                                 service status notification socket, as
 871                                 accessible via the
 872                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 873                                 call. Takes one of
 874                                 <option>none</option> (the default),
 875                                 <option>main</option> or
 876                                 <option>all</option>. If
 877                                 <option>none</option>, no daemon status
 878                                 updates are accepted from the service
 879                                 processes, all status update messages
 880                                 are ignored. If <option>main</option>,
 881                                 only service updates sent from the
 882                                 main process of the service are
 883                                 accepted. If <option>all</option>, all
 884                                 services updates from all members of
 885                                 the service's control group are
 886                                 accepted. This option should be set to
 887                                 open access to the notification socket
 888                                 when using
 889                                 <varname>Type=notify</varname> or
 890                                 <varname>WatchdogSec=</varname> (see
 891                                 above). If those options are used but
 892                                 <varname>NotifyAccess=</varname> is not
 893                                 configured, it will be implicitly set
 894                                 to
 895                                 <option>main</option>.</para></listitem>
 896                         </varlistentry>
 897
 898                         <varlistentry>
 899                                 <term><varname>Sockets=</varname></term>
 900                                 <listitem><para>Specifies the name of
 901                                 the socket units this service shall
 902                                 inherit the sockets from when the
 903                                 service is started. Normally it
 904                                 should not be necessary to use this
 905                                 setting as all sockets whose unit
 906                                 shares the same name as the service
 907                                 (ignoring the different suffix of course)
 908                                 are passed to the spawned
 909                                 process.</para>
 910
 911                                 <para>Note that the same socket may be
 912                                 passed to multiple processes at the
 913                                 same time. Also note that a different
 914                                 service may be activated on incoming
 915                                 traffic than inherits the sockets. Or
 916                                 in other words: the
 917                                 <varname>Service=</varname> setting of
 918                                 <filename>.socket</filename> units
 919                                 does not have to match the inverse of
 920                                 the <varname>Sockets=</varname>
 921                                 setting of the
 922                                 <filename>.service</filename> it
 923                                 refers to.</para>
 924
 925                                 <para>This option may appear more than
 926                                 once, in which case the list of socket
 927                                 units is merged. If the empty string
 928                                 is assigned to this option, the list of
 929                                 sockets is reset, all prior uses of
 930                                 this setting will have no
 931                                 effect.</para></listitem>
 932                         </varlistentry>
 933
 934                         <varlistentry>
 935                                 <term><varname>StartLimitInterval=</varname></term>
 936                                 <term><varname>StartLimitBurst=</varname></term>
 937
 938                                 <listitem><para>Configure service
 939                                 start rate limiting. By default,
 940                                 services which are started more often
 941                                 than 5 times within 10s are not
 942                                 permitted to start any more times
 943                                 until the 10s interval ends. With
 944                                 these two options, this rate limiting
 945                                 may be modified. Use
 946                                 <varname>StartLimitInterval=</varname>
 947                                 to configure the checking interval (defaults to
 948                                 <varname>DefaultStartLimitInterval=</varname> in
 949                                 manager configuration file, set to 0 to disable
 950                                 any kind of rate limiting). Use
 951                                 <varname>StartLimitBurst=</varname> to
 952                                 configure how many starts per interval
 953                                 are allowed (defaults to
 954                                 <varname>DefaultStartLimitBurst=</varname> in
 955                                 manager configuration file). These
 956                                 configuration options are particularly
 957                                 useful in conjunction with
 958                                 <varname>Restart=</varname>, however
 959                                 apply to all kinds of starts
 960                                 (including manual), not just those
 961                                 triggered by the
 962                                 <varname>Restart=</varname> logic.
 963                                 Note that units which are configured
 964                                 for <varname>Restart=</varname> and
 965                                 which reach the start limit are not
 966                                 attempted to be restarted anymore,
 967                                 however they may still be restarted
 968                                 manually at a later point from which
 969                                 point on the restart logic is again
 970                                 activated. Note that
 971                                 <command>systemctl
 972                                 reset-failed</command> will cause the
 973                                 restart rate counter for a service to
 974                                 be flushed, which is useful if the
 975                                 administrator wants to manually start
 976                                 a service and the start limit
 977                                 interferes with
 978                                 that.</para></listitem>
 979                         </varlistentry>
 980
 981                         <varlistentry>
 982                                 <term><varname>StartLimitAction=</varname></term>
 983
 984                                 <listitem><para>Configure the action
 985                                 to take if the rate limit configured
 986                                 with
 987                                 <varname>StartLimitInterval=</varname>
 988                                 and
 989                                 <varname>StartLimitBurst=</varname> is
 990                                 hit. Takes one of
 991                                 <option>none</option>,
 992                                 <option>reboot</option>,
 993                                 <option>reboot-force</option> or
 994                                 <option>reboot-immediate</option>. If
 995                                 <option>none</option> is set,
 996                                 hitting the rate limit will trigger no
 997                                 action besides that the start will not
 998                                 be
 999                                 permitted. <option>reboot</option>
1000                                 causes a reboot following the normal
1001                                 shutdown procedure (i.e. equivalent to
1002                                 <command>systemctl reboot</command>),
1003                                 <option>reboot-force</option> causes
1004                                 an forced reboot which will terminate
1005                                 all processes forcibly but should
1006                                 cause no dirty file systems on reboot
1007                                 (i.e. equivalent to <command>systemctl
1008                                 reboot -f</command>) and
1009                                 <option>reboot-immediate</option>
1010                                 causes immediate execution of the
1011                                 <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1012                                 system call, which might result in
1013                                 data loss.  Defaults to
1014                                 <option>none</option>.</para></listitem>
1015                         </varlistentry>
1016
1017                 </variablelist>
1018
1019                 <para>Check
1020                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1021                 and
1022                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1023                 for more settings.</para>
1024
1025         </refsect1>
1026
1027         <refsect1>
1028                 <title>Compatibility Options</title>
1029
1030                 <para>The following options are also available in the
1031                 <literal>[Service]</literal> section, but exist purely
1032                 for compatibility reasons and should not be used in
1033                 newly written service files.</para>
1034
1035                 <variablelist class='unit-directives'>
1036                         <varlistentry>
1037                                 <term><varname>SysVStartPriority=</varname></term>
1038                                 <listitem><para>Set the SysV start
1039                                 priority to use to order this service
1040                                 in relation to SysV services lacking
1041                                 LSB headers. This option is only
1042                                 necessary to fix ordering in relation
1043                                 to legacy SysV services, that have no
1044                                 ordering information encoded in the
1045                                 script headers. As such it should only
1046                                 be used as temporary compatibility
1047                                 option, and not be used in new unit
1048                                 files. Almost always it is a better
1049                                 choice to add explicit ordering
1050                                 directives via
1051                                 <varname>After=</varname> or
1052                                 <varname>Before=</varname>,
1053                                 instead. For more details see
1054                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
1055                                 used, pass an integer value in the
1056                                 range 0-99.</para></listitem>
1057                         </varlistentry>
1058
1059                 </variablelist>
1060         </refsect1>
1061
1062         <refsect1>
1063                   <title>See Also</title>
1064                   <para>
1065                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1066                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1067                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1068                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1069                           <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1070                           <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1071                           <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1072                   </para>
1073         </refsect1>
1074
1075 </refentry>