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
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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 with starting follow-up units
 176                                 as 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 with starting follow-up
 196                                 units 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 has finished
 212                                 starting up. systemd will proceed with
 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 if the process
 301                                 takes a name on the D-Bus bus.</para>
 302                                 </listitem>
 303                         </varlistentry>
 304
 305                         <varlistentry>
 306                                 <term><varname>ExecStart=</varname></term>
 307                                 <listitem><para>Commands with their
 308                                 arguments that are executed when this
 309                                 service is started. For each of the
 310                                 specified commands, the first argument
 311                                 must be an absolute and literal path
 312                                 to an executable.</para>
 313
 314                                 <para>When <varname>Type</varname> is
 315                                 not <option>oneshot</option>, only one
 316                                 command may be given. When
 317                                 <varname>Type=oneshot</varname> is
 318                                 used, more than one command may be
 319                                 specified. Multiple command lines may
 320                                 be concatenated in a single directive
 321                                 by separating them with semicolons
 322                                 (these semicolons must be passed as
 323                                 separate words). Alternatively, this
 324                                 directive may be specified more than
 325                                 once with the same effect.
 326                                 Lone semicolons may be escaped as
 327                                 <literal>\;</literal>. If the empty
 328                                 string is assigned to this option, the
 329                                 list of commands to start is reset,
 330                                 prior assignments of this option will
 331                                 have no effect.</para>
 332
 333                                 <para>Each command line is split on
 334                                 whitespace, with the first item being
 335                                 the command to execute, and the
 336                                 subsequent items being the arguments.
 337                                 Double quotes ("...") and single
 338                                 quotes ('...') may be used, in which
 339                                 case everything until the next
 340                                 matching quote becomes part of the
 341                                 same argument. Quotes themselves are
 342                                 removed after parsing. In addition, a
 343                                 trailing backslash
 344                                 (<literal>\</literal>) may be used to
 345                                 merge lines. This syntax is intended
 346                                 to be very similar to shell syntax,
 347                                 but only the meta-characters and
 348                                 expansions described in the following
 349                                 paragraphs are understood.
 350                                 Specifically, redirection using
 351                                 <literal>&lt;</literal>,
 352                                 <literal>&lt;&lt;</literal>,
 353                                 <literal>&gt;</literal>, and
 354                                 <literal>&gt;&gt;</literal>, pipes
 355                                 using <literal>|</literal>, and
 356                                 running programs in the background
 357                                 using <literal>&amp;</literal>
 358                                 and <emphasis>other elements of shell
 359                                 syntax are not supported</emphasis>.
 360                                 </para>
 361
 362                                 <para>If more than one command is
 363                                 specified, the commands are invoked
 364                                 sequentially in the order they appear
 365                                 in the unit file. If one of the
 366                                 commands fails (and is not prefixed
 367                                 with <literal>-</literal>), other lines
 368                                 are not executed, and the unit is
 369                                 considered failed.</para>
 370
 371                                 <para>Unless
 372                                 <varname>Type=forking</varname> is
 373                                 set, the process started via this
 374                                 command line will be considered the
 375                                 main process of the daemon.</para>
 376
 377                                 <para>The command line accepts
 378                                 <literal>%</literal> specifiers as
 379                                 described in
 380                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 381                                 Note that the first argument of the
 382                                 command line (i.e. the program to
 383                                 execute) may not include
 384                                 specifiers.</para>
 385
 386                                 <para>Basic environment variable
 387                                 substitution is supported. Use
 388                                 <literal>${FOO}</literal> as part of a
 389                                 word, or as a word of its own, on the
 390                                 command line, in which case it will be
 391                                 replaced by the value of the
 392                                 environment variable including all
 393                                 whitespace it contains, resulting in a
 394                                 single argument. Use
 395                                 <literal>$FOO</literal> as a separate
 396                                 word on the command line, in which
 397                                 case it will be replaced by the value
 398                                 of the environment variable split at
 399                                 whitespace, resulting in zero or more
 400                                 arguments. To pass a literal dollar
 401                                 sign, use <literal>$$</literal>.
 402                                 Variables whose value is not known at
 403                                 expansion time are treated as empty
 404                                 strings. Note that the first argument
 405                                 (i.e. the program to execute) may not
 406                                 be a variable.</para>
 407
 408                                 <para>Variables to be used in this
 409                                 fashion may be defined through
 410                                 <varname>Environment=</varname> and
 411                                 <varname>EnvironmentFile=</varname>.
 412                                 In addition, variables listed in the
 413                                 section "Environment variables in
 414                                 spawned processes" in
 415                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 416                                 which are considered "static
 417                                 configuration", may be used (this includes
 418                                 e.g. <varname>$USER</varname>, but not
 419                                 <varname>$TERM</varname>).</para>
 420
 421                                 <para>Optionally, if the absolute file
 422                                 name is prefixed with
 423                                 <literal>@</literal>, the second token
 424                                 will be passed as
 425                                 <literal>argv[0]</literal> to the
 426                                 executed process, followed by the
 427                                 further arguments specified. If the
 428                                 absolute filename is prefixed with
 429                                 <literal>-</literal>, an exit code of
 430                                 the command normally considered a
 431                                 failure (i.e. non-zero exit status or
 432                                 abnormal exit due to signal) is ignored
 433                                 and considered success. If both
 434                                 <literal>-</literal> and
 435                                 <literal>@</literal> are used, they
 436                                 can appear in either order.</para>
 437
 438                                 <para>Note that this setting does not
 439                                 directly support shell command
 440                                 lines. If shell command lines are to
 441                                 be used, they need to be passed
 442                                 explicitly to a shell implementation
 443                                 of some kind. Example:</para>
 444                                 <programlisting>ExecStart=/bin/sh -c 'dmesg | tac'</programlisting>
 445                                 <para>Example:</para>
 446                                 <programlisting>ExecStart=/bin/echo one ; /bin/echo "two two"</programlisting>
 447                                 <para>This will execute
 448                                 <command>/bin/echo</command> two
 449                                 times, each time with one argument:
 450                                 <literal>one</literal> and
 451                                 <literal>two two</literal>,
 452                                 respectively. Because two commands are
 453                                 specified,
 454                                 <varname>Type=oneshot</varname> must
 455                                 be used.</para>
 456
 457                                 <para>Example:</para>
 458                                 <programlisting>ExecStart=/bin/echo / &gt;/dev/null &amp; \; \
 459 /bin/ls</programlisting>
 460                                 <para>This will execute
 461                                 <command>/bin/echo</command> with five
 462                                 arguments: <literal>/</literal>,
 463                                 <literal>&gt;/dev/null</literal>,
 464                                 <literal>&amp;</literal>,
 465                                 <literal>;</literal>, and
 466                                 <literal>/bin/ls</literal>.</para>
 467
 468                                 <para>Example:</para>
 469                                 <programlisting>Environment="ONE=one" 'TWO=two two'
 470 ExecStart=/bin/echo $ONE $TWO ${TWO}</programlisting>
 471                                 <para>This will execute
 472                                 <command>/bin/echo</command> with four
 473                                 arguments: <literal>one</literal>,
 474                                 <literal>two</literal>,
 475                                 <literal>two</literal>, and
 476                                 <literal>two two</literal>.</para>
 477                               </listitem>
 478                         </varlistentry>
 479
 480                         <varlistentry>
 481                                 <term><varname>ExecStartPre=</varname></term>
 482                                 <term><varname>ExecStartPost=</varname></term>
 483                                 <listitem><para>Additional commands
 484                                 that are executed before or after
 485                                 the command in
 486                                 <varname>ExecStart=</varname>, respectively.
 487                                 Syntax is the same as for
 488                                 <varname>ExecStart=</varname>, except
 489                                 that multiple command lines are allowed
 490                                 and the commands are executed one
 491                                 after the other, serially.</para>
 492
 493                                 <para>If any of those commands (not
 494                                 prefixed with <literal>-</literal>)
 495                                 fail, the rest are not executed and
 496                                 the unit is considered failed.</para>
 497                                 </listitem>
 498                         </varlistentry>
 499
 500                         <varlistentry>
 501                                 <term><varname>ExecReload=</varname></term>
 502                                 <listitem><para>Commands to execute to
 503                                 trigger a configuration reload in the
 504                                 service. This argument takes multiple
 505                                 command lines, following the same
 506                                 scheme as described for
 507                                 <varname>ExecStart=</varname>
 508                                 above. Use of this setting is
 509                                 optional. Specifier and environment
 510                                 variable substitution is supported
 511                                 here following the same scheme as for
 512                                 <varname>ExecStart=</varname>.</para>
 513
 514                                 <para>One additional, special
 515                                 environment variable is set: if known,
 516                                 <varname>$MAINPID</varname> is set to
 517                                 the main process of the daemon, and
 518                                 may be used for command lines like the
 519                                 following:</para>
 520
 521                                 <programlisting>/bin/kill -HUP $MAINPID</programlisting>
 522
 523                                 <para>Note however that reloading a
 524                                 daemon by sending a signal (as with
 525                                 the example line above) is usually not
 526                                 a good choice, because this is an
 527                                 asynchronous operation and hence not
 528                                 suitable to order reloads of multiple
 529                                 services against each other. It is
 530                                 strongly recommended to set
 531                                 <varname>ExecReload=</varname> to a
 532                                 command that not only triggers a
 533                                 configuration reload of the daemon,
 534                                 but also synchronously waits for it to
 535                                 complete.</para>
 536                                 </listitem>
 537                         </varlistentry>
 538
 539                         <varlistentry>
 540                                 <term><varname>ExecStop=</varname></term>
 541                                 <listitem><para>Commands to execute to
 542                                 stop the service started via
 543                                 <varname>ExecStart=</varname>. This
 544                                 argument takes multiple command lines,
 545                                 following the same scheme as described
 546                                 for <varname>ExecStart=</varname>
 547                                 above. Use of this setting is
 548                                 optional. After the commands configured
 549                                 in this option are run, all processes
 550                                 remaining for a service are
 551                                 terminated according to the
 552                                 <varname>KillMode=</varname> setting
 553                                 (see
 554                                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>). If
 555                                 this option is not specified, the
 556                                 process is terminated immediately when
 557                                 service stop is requested. Specifier
 558                                 and environment variable substitution
 559                                 is supported (including
 560                                 <varname>$MAINPID</varname>, see
 561                                 above).</para></listitem>
 562                         </varlistentry>
 563
 564                         <varlistentry>
 565                                 <term><varname>ExecStopPost=</varname></term>
 566                                 <listitem><para>Additional commands
 567                                 that are executed after the service
 568                                 was stopped. This includes cases where
 569                                 the commands configured in
 570                                 <varname>ExecStop=</varname> were used,
 571                                 where the service does not have any
 572                                 <varname>ExecStop=</varname> defined, or
 573                                 where the service exited unexpectedly. This
 574                                 argument takes multiple command lines,
 575                                 following the same scheme as described
 576                                 for <varname>ExecStart</varname>. Use
 577                                 of these settings is
 578                                 optional. Specifier and environment
 579                                 variable substitution is
 580                                 supported.</para></listitem>
 581                         </varlistentry>
 582
 583                         <varlistentry>
 584                                 <term><varname>RestartSec=</varname></term>
 585                                 <listitem><para>Configures the time to
 586                                 sleep before restarting a service (as
 587                                 configured with
 588                                 <varname>Restart=</varname>). Takes a
 589                                 unit-less value in seconds, or a time
 590                                 span value such as "5min
 591                                 20s". Defaults to
 592                                 100ms.</para></listitem>
 593                         </varlistentry>
 594
 595                         <varlistentry>
 596                                 <term><varname>TimeoutStartSec=</varname></term>
 597                                 <listitem><para>Configures the time to
 598                                 wait for start-up. If a
 599                                 daemon service does not signal
 600                                 start-up completion within the
 601                                 configured time, the service will be
 602                                 considered failed and will be shut
 603                                 down again.
 604                                 Takes a unit-less value in seconds, or a
 605                                 time span value such as "5min
 606                                 20s". Pass <literal>0</literal> to
 607                                 disable the timeout logic. Defaults to
 608                                 <varname>TimeoutStartSec=</varname> from
 609                                 the manager configuration file, except
 610                                 when <varname>Type=oneshot</varname> is
 611                                 used, in which case the timeout
 612                                 is disabled by default.
 613                                 </para></listitem>
 614                         </varlistentry>
 615
 616                         <varlistentry>
 617                                 <term><varname>TimeoutStopSec=</varname></term>
 618                                 <listitem><para>Configures the time to
 619                                 wait for stop. If a service is asked
 620                                 to stop, but does not terminate in the
 621                                 specified time, it will be terminated
 622                                 forcibly via <constant>SIGTERM</constant>,
 623                                 and after another timeout of equal duration
 624                                 with <constant>SIGKILL</constant> (see
 625                                 <varname>KillMode=</varname>
 626                                 in <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
 627                                 Takes a unit-less value in seconds, or a
 628                                 time span value such as "5min
 629                                 20s". Pass <literal>0</literal> to disable
 630                                 the timeout logic. Defaults to
 631                                 <varname>TimeoutStartSec=</varname> from the
 632                                 manager configuration file.
 633                                 </para></listitem>
 634                         </varlistentry>
 635
 636                         <varlistentry>
 637                                 <term><varname>TimeoutSec=</varname></term>
 638                                 <listitem><para>A shorthand for configuring
 639                                 both <varname>TimeoutStartSec=</varname>
 640                                 and <varname>TimeoutStopSec=</varname>
 641                                 to the specified value.
 642                                 </para></listitem>
 643                         </varlistentry>
 644
 645                         <varlistentry>
 646                                 <term><varname>WatchdogSec=</varname></term>
 647                                 <listitem><para>Configures the
 648                                 watchdog timeout for a service. The
 649                                 watchdog is activated when the start-up is
 650                                 completed. The service must call
 651                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 652                                 regularly with <literal>WATCHDOG=1</literal>
 653                                 (i.e. the "keep-alive ping"). If the time
 654                                 between two such calls is larger than
 655                                 the configured time, then the service
 656                                 is placed in a failed state. By
 657                                 setting <varname>Restart=</varname> to
 658                                 <option>on-failure</option> or
 659                                 <option>always</option>, the service
 660                                 will be automatically restarted. The
 661                                 time configured here will be passed to
 662                                 the executed service process in the
 663                                 <varname>WATCHDOG_USEC=</varname>
 664                                 environment variable. This allows
 665                                 daemons to automatically enable the
 666                                 keep-alive pinging logic if watchdog
 667                                 support is enabled for the service. If
 668                                 this option is used,
 669                                 <varname>NotifyAccess=</varname> (see
 670                                 below) should be set to open access to
 671                                 the notification socket provided by
 672                                 systemd. If
 673                                 <varname>NotifyAccess=</varname> is
 674                                 not set, it will be implicitly set to
 675                                 <option>main</option>. Defaults to 0,
 676                                 which disables this
 677                                 feature.</para></listitem>
 678                         </varlistentry>
 679
 680                         <varlistentry>
 681                                 <term><varname>Restart=</varname></term>
 682                                 <listitem><para>Configures whether the
 683                                 service shall be restarted when the
 684                                 service process exits, is killed,
 685                                 or a timeout is reached. The service
 686                                 process may be the main service
 687                                 process, but it may also be one of the
 688                                 processes specified with
 689                                 <varname>ExecStartPre=</varname>,
 690                                 <varname>ExecStartPost=</varname>,
 691                                 <varname>ExecStop=</varname>,
 692                                 <varname>ExecStopPost=</varname>, or
 693                                 <varname>ExecReload=</varname>.
 694                                 When the death of the process is a
 695                                 result of systemd operation (e.g. service
 696                                 stop or restart), the service will not be
 697                                 restarted. Timeouts include missing
 698                                 the watchdog "keep-alive ping"
 699                                 deadline and a service start, reload,
 700                                 and stop operation timeouts.</para>
 701
 702                                 <para>Takes one of
 703                                 <option>no</option>,
 704                                 <option>on-success</option>,
 705                                 <option>on-failure</option>,
 706                                 <option>on-abnormal</option>,
 707                                 <option>on-watchdog</option>,
 708                                 <option>on-abort</option>, or
 709                                 <option>always</option>. If set to
 710                                 <option>no</option> (the default), the
 711                                 service will not be restarted. If set
 712                                 to <option>on-success</option>, it
 713                                 will be restarted only when the
 714                                 service process exits cleanly.  In
 715                                 this context, a clean exit means an
 716                                 exit code of 0, or one of the signals
 717                                 <constant>SIGHUP</constant>,
 718                                 <constant>SIGINT</constant>,
 719                                 <constant>SIGTERM</constant> or
 720                                 <constant>SIGPIPE</constant>, and
 721                                 additionally, exit statuses and
 722                                 signals specified in
 723                                 <varname>SuccessExitStatus=</varname>.
 724                                 If set to <option>on-failure</option>,
 725                                 the service will be restarted when the
 726                                 process exits with a non-zero exit
 727                                 code, is terminated by a signal
 728                                 (including on core dump, but excluding
 729                                 the aforementiond four signals), when
 730                                 an operation (such as service reload)
 731                                 times out, and when the configured
 732                                 watchdog timeout is triggered.  If set
 733                                 to <option>on-abnormal</option>, the
 734                                 service will be restarted when the
 735                                 process is terminated by a signal
 736                                 (including on core dump, excluding the
 737                                 aforementioned four signals), when an
 738                                 operation times out, or when the
 739                                 watchdog timeout is triggered. If set
 740                                 to <option>on-abort</option>, the
 741                                 service will be restarted only if the
 742                                 service process exits due to an
 743                                 uncaught signal not specified as a
 744                                 clean exit status.  If set to
 745                                 <option>on-watchdog</option>, the
 746                                 service will be restarted only if the
 747                                 watchdog timeout for the service
 748                                 expires.  If set to
 749                                 <option>always</option>, the service
 750                                 will be restarted regardless of
 751                                 whether it exited cleanly or not, got
 752                                 terminated abnormally by a signal, or
 753                                 hit a timeout.</para>
 754
 755                                 <table>
 756                                         <title>Exit causes and the effect of the <varname>Restart=</varname> settings on them</title>
 757
 758                                         <tgroup cols='2'>
 759                                                 <colspec colname='path' />
 760                                                 <colspec colname='expl' />
 761                                                 <thead>
 762                                                         <row>
 763                                                                 <entry>Restart settings/Exit causes</entry>
 764                                                                 <entry><option>no</option></entry>
 765                                                                 <entry><option>always</option></entry>
 766                                                                 <entry><option>on-success</option></entry>
 767                                                                 <entry><option>on-failure</option></entry>
 768                                                                 <entry><option>on-abnormal</option></entry>
 769                                                                 <entry><option>on-abort</option></entry>
 770                                                                 <entry><option>on-watchdog</option></entry>
 771                                                         </row>
 772                                                 </thead>
 773                                                 <tbody>
 774                                                         <row>
 775                                                                 <entry>Clean exit code or signal</entry>
 776                                                                 <entry/>
 777                                                                 <entry>X</entry>
 778                                                                 <entry>X</entry>
 779                                                                 <entry/>
 780                                                                 <entry/>
 781                                                                 <entry/>
 782                                                                 <entry/>
 783                                                         </row>
 784                                                         <row>
 785                                                                 <entry>Unclean exit code</entry>
 786                                                                 <entry/>
 787                                                                 <entry>X</entry>
 788                                                                 <entry/>
 789                                                                 <entry>X</entry>
 790                                                                 <entry/>
 791                                                                 <entry/>
 792                                                                 <entry/>
 793                                                         </row>
 794                                                         <row>
 795                                                                 <entry>Unclean signal</entry>
 796                                                                 <entry/>
 797                                                                 <entry>X</entry>
 798                                                                 <entry/>
 799                                                                 <entry>X</entry>
 800                                                                 <entry>X</entry>
 801                                                                 <entry>X</entry>
 802                                                                 <entry/>
 803                                                         </row>
 804                                                         <row>
 805                                                                 <entry>Timeout</entry>
 806                                                                 <entry/>
 807                                                                 <entry>X</entry>
 808                                                                 <entry/>
 809                                                                 <entry>X</entry>
 810                                                                 <entry>X</entry>
 811                                                                 <entry/>
 812                                                                 <entry/>
 813                                                         </row>
 814                                                         <row>
 815                                                                 <entry>Watchdog</entry>
 816                                                                 <entry/>
 817                                                                 <entry>X</entry>
 818                                                                 <entry/>
 819                                                                 <entry>X</entry>
 820                                                                 <entry>X</entry>
 821                                                                 <entry/>
 822                                                                 <entry>X</entry>
 823                                                         </row>
 824                                                 </tbody>
 825                                         </tgroup>
 826                                 </table>
 827
 828                                 <para>In addition to the above settings,
 829                                 the service will not be restarted if the
 830                                 exit code or signal is specified in
 831                                 <varname>RestartPreventExitStatus=</varname>
 832                                 (see below).</para>
 833
 834                                 <para>Setting this to
 835                                 <option>on-failure</option> is the
 836                                 recommended choice for long-running
 837                                 services, in order to increase
 838                                 reliability by attempting automatic
 839                                 recovery from errors. For services
 840                                 that shall be able to terminate on
 841                                 their own choice (and avoiding
 842                                 immediate restart)
 843                                 <option>on-abnormal</option> is an
 844                                 alternative choice.</para>
 845                                 </listitem>
 846                         </varlistentry>
 847
 848                         <varlistentry>
 849                                 <term><varname>SuccessExitStatus=</varname></term>
 850                                 <listitem><para>Takes a list of exit
 851                                 status definitions that when returned
 852                                 by the main service process will be
 853                                 considered successful termination, in
 854                                 addition to the normal successful exit
 855                                 code 0 and the signals <constant>SIGHUP</constant>, <constant>SIGINT</constant>,
 856                                 <constant>SIGTERM</constant>, and <constant>SIGPIPE</constant>. Exit status
 857                                 definitions can either be numeric exit
 858                                 codes or termination signal names,
 859                                 separated by spaces. For example:
 860                                 <programlisting>SuccessExitStatus=1 2 8 <constant>SIGKILL</constant></programlisting>
 861                                 ensures that exit codes 1, 2, 8 and
 862                                 the termination signal
 863                                 <constant>SIGKILL</constant> are
 864                                 considered clean service terminations.
 865                                 </para>
 866
 867                                 <para>Note that if a process has a
 868                                 signal handler installed and exits by
 869                                 calling
 870                                 <citerefentry><refentrytitle>_exit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 871                                 in response to a signal, the
 872                                 information about the signal is lost.
 873                                 Programs should instead perform cleanup and kill themselves with the same signal instead. See
 874                                 <ulink url="http://www.cons.org/cracauer/sigint.html">Proper handling of SIGINT/SIGQUIT — How to be a proper program</ulink>.</para>
 875
 876                                 <para>This option may appear more than once,
 877                                 in which case the list of successful
 878                                 exit statuses is merged. If the empty
 879                                 string is assigned to this option, the
 880                                 list is reset, all prior assignments
 881                                 of this option will have no
 882                                 effect.</para></listitem>
 883                         </varlistentry>
 884
 885                         <varlistentry>
 886                                 <term><varname>RestartPreventExitStatus=</varname></term>
 887                                 <listitem><para>Takes a list of exit
 888                                 status definitions that when returned
 889                                 by the main service process will
 890                                 prevent automatic service restarts,
 891                                 regardless of the restart setting
 892                                 configured with
 893                                 <varname>Restart=</varname>. Exit
 894                                 status definitions can either be
 895                                 numeric exit codes or termination
 896                                 signal names, and are separated by
 897                                 spaces. Defaults to the empty list, so
 898                                 that, by default, no exit status is
 899                                 excluded from the configured restart
 900                                 logic. Example:
 901                                 <literal>RestartPreventExitStatus=1 6
 902                                 SIGABRT</literal>, ensures that exit
 903                                 codes 1 and 6 and the termination
 904                                 signal <constant>SIGABRT</constant> will
 905                                 not result in automatic service
 906                                 restarting. This
 907                                 option may appear more than once, in
 908                                 which case the list of restart-preventing
 909                                 statuses is merged. If the empty
 910                                 string is assigned to this option, the
 911                                 list is reset and all prior assignments
 912                                 of this option will have no
 913                                 effect.</para></listitem>
 914                         </varlistentry>
 915
 916                         <varlistentry>
 917                                 <term><varname>PermissionsStartOnly=</varname></term>
 918                                 <listitem><para>Takes a boolean
 919                                 argument. If true, the permission-related
 920                                 execution options, as
 921                                 configured with
 922                                 <varname>User=</varname> and similar
 923                                 options (see
 924                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 925                                 for more information), are only applied
 926                                 to the process started with
 927                                 <varname>ExecStart=</varname>, and not
 928                                 to the various other
 929                                 <varname>ExecStartPre=</varname>,
 930                                 <varname>ExecStartPost=</varname>,
 931                                 <varname>ExecReload=</varname>,
 932                                 <varname>ExecStop=</varname>, and
 933                                 <varname>ExecStopPost=</varname>
 934                                 commands. If false, the setting is
 935                                 applied to all configured commands the
 936                                 same way. Defaults to
 937                                 false.</para></listitem>
 938                         </varlistentry>
 939
 940                         <varlistentry>
 941                                 <term><varname>RootDirectoryStartOnly=</varname></term>
 942                                 <listitem><para>Takes a boolean
 943                                 argument. If true, the root directory,
 944                                 as configured with the
 945                                 <varname>RootDirectory=</varname>
 946                                 option (see
 947                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 948                                 for more information), is only applied
 949                                 to the process started with
 950                                 <varname>ExecStart=</varname>, and not
 951                                 to the various other
 952                                 <varname>ExecStartPre=</varname>,
 953                                 <varname>ExecStartPost=</varname>,
 954                                 <varname>ExecReload=</varname>,
 955                                 <varname>ExecStop=</varname>, and
 956                                 <varname>ExecStopPost=</varname>
 957                                 commands. If false, the setting is
 958                                 applied to all configured commands the
 959                                 same way. Defaults to
 960                                 false.</para></listitem>
 961                         </varlistentry>
 962
 963                         <varlistentry>
 964                                 <term><varname>NonBlocking=</varname></term>
 965                                 <listitem><para>Set the
 966                                 <constant>O_NONBLOCK</constant> flag
 967                                 for all file descriptors passed via
 968                                 socket-based activation. If true, all
 969                                 file descriptors >= 3 (i.e. all except
 970                                 stdin, stdout, and stderr) will have
 971                                 the <constant>O_NONBLOCK</constant> flag
 972                                 set and hence are in
 973                                 non-blocking mode. This option is only
 974                                 useful in conjunction with a socket
 975                                 unit, as described in
 976                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
 977                                 to false.</para></listitem>
 978                         </varlistentry>
 979
 980                         <varlistentry>
 981                                 <term><varname>NotifyAccess=</varname></term>
 982                                 <listitem><para>Controls access to the
 983                                 service status notification socket, as
 984                                 accessible via the
 985                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 986                                 call. Takes one of
 987                                 <option>none</option> (the default),
 988                                 <option>main</option> or
 989                                 <option>all</option>. If
 990                                 <option>none</option>, no daemon status
 991                                 updates are accepted from the service
 992                                 processes, all status update messages
 993                                 are ignored. If <option>main</option>,
 994                                 only service updates sent from the
 995                                 main process of the service are
 996                                 accepted. If <option>all</option>, all
 997                                 services updates from all members of
 998                                 the service's control group are
 999                                 accepted. This option should be set to
1000                                 open access to the notification socket
1001                                 when using
1002                                 <varname>Type=notify</varname> or
1003                                 <varname>WatchdogSec=</varname> (see
1004                                 above). If those options are used but
1005                                 <varname>NotifyAccess=</varname> is not
1006                                 configured, it will be implicitly set
1007                                 to
1008                                 <option>main</option>.</para></listitem>
1009                         </varlistentry>
1010
1011                         <varlistentry>
1012                                 <term><varname>Sockets=</varname></term>
1013                                 <listitem><para>Specifies the name of
1014                                 the socket units this service shall
1015                                 inherit the sockets from when the
1016                                 service is started. Normally it
1017                                 should not be necessary to use this
1018                                 setting as all sockets whose unit
1019                                 shares the same name as the service
1020                                 (ignoring the different suffix of course)
1021                                 are passed to the spawned
1022                                 process.</para>
1023
1024                                 <para>Note that the same socket may be
1025                                 passed to multiple processes at the
1026                                 same time. Also note that a different
1027                                 service may be activated on incoming
1028                                 traffic than that which inherits the
1029                                 sockets. Or in other words: the
1030                                 <varname>Service=</varname> setting of
1031                                 <filename>.socket</filename> units
1032                                 does not have to match the inverse of
1033                                 the <varname>Sockets=</varname>
1034                                 setting of the
1035                                 <filename>.service</filename> it
1036                                 refers to.</para>
1037
1038                                 <para>This option may appear more than
1039                                 once, in which case the list of socket
1040                                 units is merged. If the empty string
1041                                 is assigned to this option, the list of
1042                                 sockets is reset, and all prior uses of
1043                                 this setting will have no
1044                                 effect.</para></listitem>
1045                         </varlistentry>
1046
1047                         <varlistentry>
1048                                 <term><varname>StartLimitInterval=</varname></term>
1049                                 <term><varname>StartLimitBurst=</varname></term>
1050
1051                                 <listitem><para>Configure service
1052                                 start rate limiting. By default,
1053                                 services which are started more
1054                                 than 5 times within 10 seconds are not
1055                                 permitted to start any more times
1056                                 until the 10 second interval ends. With
1057                                 these two options, this rate limiting
1058                                 may be modified. Use
1059                                 <varname>StartLimitInterval=</varname>
1060                                 to configure the checking interval (defaults to
1061                                 <varname>DefaultStartLimitInterval=</varname> in
1062                                 manager configuration file, set to 0 to disable
1063                                 any kind of rate limiting). Use
1064                                 <varname>StartLimitBurst=</varname> to
1065                                 configure how many starts per interval
1066                                 are allowed (defaults to
1067                                 <varname>DefaultStartLimitBurst=</varname> in
1068                                 manager configuration file). These
1069                                 configuration options are particularly
1070                                 useful in conjunction with
1071                                 <varname>Restart=</varname>; however,
1072                                 they apply to all kinds of starts
1073                                 (including manual), not just those
1074                                 triggered by the
1075                                 <varname>Restart=</varname> logic.
1076                                 Note that units which are configured
1077                                 for <varname>Restart=</varname> and
1078                                 which reach the start limit are not
1079                                 attempted to be restarted anymore;
1080                                 however, they may still be restarted
1081                                 manually at a later point, from which
1082                                 point on, the restart logic is again
1083                                 activated. Note that
1084                                 <command>systemctl
1085                                 reset-failed</command> will cause the
1086                                 restart rate counter for a service to
1087                                 be flushed, which is useful if the
1088                                 administrator wants to manually start
1089                                 a service and the start limit
1090                                 interferes with
1091                                 that.</para></listitem>
1092                         </varlistentry>
1093
1094                         <varlistentry>
1095                                 <term><varname>StartLimitAction=</varname></term>
1096
1097                                 <listitem><para>Configure the action
1098                                 to take if the rate limit configured
1099                                 with
1100                                 <varname>StartLimitInterval=</varname>
1101                                 and
1102                                 <varname>StartLimitBurst=</varname> is
1103                                 hit. Takes one of
1104                                 <option>none</option>,
1105                                 <option>reboot</option>,
1106                                 <option>reboot-force</option>, or
1107                                 <option>reboot-immediate</option>. If
1108                                 <option>none</option> is set,
1109                                 hitting the rate limit will trigger no
1110                                 action besides that the start will not
1111                                 be permitted. <option>reboot</option>
1112                                 causes a reboot following the normal
1113                                 shutdown procedure (i.e. equivalent to
1114                                 <command>systemctl reboot</command>).
1115                                 <option>reboot-force</option> causes
1116                                 a forced reboot which will terminate
1117                                 all processes forcibly but should
1118                                 cause no dirty file systems on reboot
1119                                 (i.e. equivalent to <command>systemctl
1120                                 reboot -f</command>) and
1121                                 <option>reboot-immediate</option>
1122                                 causes immediate execution of the
1123                                 <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1124                                 system call, which might result in
1125                                 data loss. Defaults to
1126                                 <option>none</option>.</para></listitem>
1127                         </varlistentry>
1128
1129                         <varlistentry>
1130                                 <term><varname>RebootArgument=</varname></term>
1131                                 <listitem><para>Configure the optional
1132                                 argument for the
1133                                 <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1134                                 system call if
1135                                 <varname>StartLimitAction=</varname>
1136                                 is a reboot action. This works just
1137                                 like the optional argument to
1138                                 <command>systemctl reboot</command>
1139                                 command.</para></listitem>
1140                         </varlistentry>
1141
1142                         <varlistentry>
1143                                 <term><varname>FailureAction=</varname></term>
1144                                 <listitem><para>Configure the action
1145                                 to take when the service enters a failed
1146                                 state. Takes the same values as
1147                                 <varname>StartLimitAction=</varname>
1148                                 and executes the same actions.
1149                                 Defaults to <option>none</option>.
1150                                 </para></listitem>
1151                         </varlistentry>
1152
1153                 </variablelist>
1154
1155                 <para>Check
1156                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1157                 and
1158                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1159                 for more settings.</para>
1160
1161         </refsect1>
1162
1163         <refsect1>
1164                 <title>Compatibility Options</title>
1165
1166                 <para>The following options are also available in the
1167                 <literal>[Service]</literal> section, but exist purely
1168                 for compatibility reasons and should not be used in
1169                 newly written service files.</para>
1170
1171                 <variablelist class='unit-directives'>
1172                         <varlistentry>
1173                                 <term><varname>SysVStartPriority=</varname></term>
1174                                 <listitem><para>Set the SysV start
1175                                 priority to use to order this service
1176                                 in relation to SysV services lacking
1177                                 LSB headers. This option is only
1178                                 necessary to fix ordering in relation
1179                                 to legacy SysV services that have no
1180                                 ordering information encoded in the
1181                                 script headers. As such, it should only
1182                                 be used as a temporary compatibility
1183                                 option and should not be used in new unit
1184                                 files. Almost always, it is a better
1185                                 choice to add explicit ordering
1186                                 directives via
1187                                 <varname>After=</varname> or
1188                                 <varname>Before=</varname>,
1189                                 instead. For more details, see
1190                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1191                                 If used, pass an integer value in the
1192                                 range 0-99.</para></listitem>
1193                         </varlistentry>
1194                 </variablelist>
1195         </refsect1>
1196
1197         <refsect1>
1198                   <title>See Also</title>
1199                   <para>
1200                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1201                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1202                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1203                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1204                           <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1205                           <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1206                           <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1207                   </para>
1208         </refsect1>
1209
1210 </refentry>