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'
 446                                 </programlisting>
 447
 448                                 <para>Example:</para>
 449                                 <programlisting>ExecStart=/bin/echo one ; /bin/echo "two two"
 450                                 </programlisting>
 451                                 <para>This will execute
 452                                 <command>/bin/echo</command> two
 453                                 times, each time with one argument,
 454                                 <literal>one</literal> and
 455                                 <literal>two two</literal>,
 456                                 respectively. Since two commands are
 457                                 specified,
 458                                 <varname>Type=oneshot</varname> must
 459                                 be used.</para>
 460
 461                                 <para>Example:</para>
 462                                 <programlisting>ExecStart=/bin/echo / &gt;/dev/null &amp; \; \
 463 /bin/ls
 464                                 </programlisting>
 465                                 <para>This will execute
 466                                 <command>/bin/echo</command> with five
 467                                 arguments: <literal>/</literal>,
 468                                 <literal>&gt;/dev/null</literal>,
 469                                 <literal>&amp;</literal>,
 470                                 <literal>;</literal>, and
 471                                 <literal>/bin/ls</literal>.</para>
 472
 473                                 <para>Example:</para>
 474                                 <programlisting>Environment="ONE=one" 'TWO=two two'
 475 ExecStart=/bin/echo $ONE $TWO ${TWO}
 476                                 </programlisting>
 477                                 <para>This will execute
 478                                 <command>/bin/echo</command> with four
 479                                 arguments: <literal>one</literal>,
 480                                 <literal>two</literal>,
 481                                 <literal>two</literal>, and
 482                                 <literal>two two</literal>.</para>
 483                               </listitem>
 484                         </varlistentry>
 485
 486                         <varlistentry>
 487                                 <term><varname>ExecStartPre=</varname></term>
 488                                 <term><varname>ExecStartPost=</varname></term>
 489                                 <listitem><para>Additional commands
 490                                 that are executed before or after
 491                                 the command in
 492                                 <varname>ExecStart=</varname>, respectively.
 493                                 Syntax is the same as for
 494                                 <varname>ExecStart=</varname>, except
 495                                 that multiple command lines are allowed
 496                                 and the commands are executed one
 497                                 after the other, serially.</para>
 498
 499                                 <para>If any of those commands (not
 500                                 prefixed with <literal>-</literal>)
 501                                 fail, the rest are not executed and
 502                                 the unit is considered failed.</para>
 503                                 </listitem>
 504                         </varlistentry>
 505
 506                         <varlistentry>
 507                                 <term><varname>ExecReload=</varname></term>
 508                                 <listitem><para>Commands to execute to
 509                                 trigger a configuration reload in the
 510                                 service. This argument takes multiple
 511                                 command lines, following the same
 512                                 scheme as described for
 513                                 <varname>ExecStart=</varname>
 514                                 above. Use of this setting is
 515                                 optional. Specifier and environment
 516                                 variable substitution is supported
 517                                 here following the same scheme as for
 518                                 <varname>ExecStart=</varname>.</para>
 519
 520                                 <para>One additional special
 521                                 environment variables is set: if known
 522                                 <varname>$MAINPID</varname> is set to
 523                                 the main process of the daemon, and
 524                                 may be used for command lines like the
 525                                 following:</para>
 526
 527                                 <programlisting>/bin/kill -HUP $MAINPID</programlisting>
 528                                 </listitem>
 529                         </varlistentry>
 530
 531                         <varlistentry>
 532                                 <term><varname>ExecStop=</varname></term>
 533                                 <listitem><para>Commands to execute to
 534                                 stop the service started via
 535                                 <varname>ExecStart=</varname>. This
 536                                 argument takes multiple command lines,
 537                                 following the same scheme as described
 538                                 for <varname>ExecStart=</varname>
 539                                 above. Use of this setting is
 540                                 optional. All processes remaining for
 541                                 a service after the commands
 542                                 configured in this option are run are
 543                                 terminated according to the
 544                                 <varname>KillMode=</varname> setting
 545                                 (see
 546                                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>). If
 547                                 this option is not specified, the
 548                                 process is terminated right-away when
 549                                 service stop is requested. Specifier
 550                                 and environment variable substitution
 551                                 is supported (including
 552                                 <varname>$MAINPID</varname>, see
 553                                 above).</para></listitem>
 554                         </varlistentry>
 555
 556                         <varlistentry>
 557                                 <term><varname>ExecStopPost=</varname></term>
 558                                 <listitem><para>Additional commands
 559                                 that are executed after the service
 560                                 was stopped. This includes cases where
 561                                 the commands configured in
 562                                 <varname>ExecStop=</varname> were used,
 563                                 where the service does not have any
 564                                 <varname>ExecStop=</varname> defined, or
 565                                 where the service exited unexpectedly. This
 566                                 argument takes multiple command lines,
 567                                 following the same scheme as described
 568                                 for <varname>ExecStart</varname>. Use
 569                                 of these settings is
 570                                 optional. Specifier and environment
 571                                 variable substitution is
 572                                 supported.</para></listitem>
 573                         </varlistentry>
 574
 575                         <varlistentry>
 576                                 <term><varname>RestartSec=</varname></term>
 577                                 <listitem><para>Configures the time to
 578                                 sleep before restarting a service (as
 579                                 configured with
 580                                 <varname>Restart=</varname>). Takes a
 581                                 unit-less value in seconds, or a time
 582                                 span value such as "5min
 583                                 20s". Defaults to
 584                                 100ms.</para></listitem>
 585                         </varlistentry>
 586
 587                         <varlistentry>
 588                                 <term><varname>TimeoutStartSec=</varname></term>
 589                                 <listitem><para>Configures the time to
 590                                 wait for start-up. If a
 591                                 daemon service does not signal
 592                                 start-up completion within the
 593                                 configured time, the service will be
 594                                 considered failed and be shut down
 595                                 again.
 596                                 Takes a unit-less value in seconds, or a
 597                                 time span value such as "5min
 598                                 20s". Pass 0 to disable the timeout
 599                                 logic. Defaults to <varname>TimeoutStartSec=</varname> from the
 600                                 manager configuration file, except when
 601                                 <varname>Type=oneshot</varname> is
 602                                 used, in which case the timeout
 603                                 is disabled by default.
 604                                 </para></listitem>
 605                         </varlistentry>
 606
 607                         <varlistentry>
 608                                 <term><varname>TimeoutStopSec=</varname></term>
 609                                 <listitem><para>Configures the time to
 610                                 wait for stop. If a service is asked
 611                                 to stop but does not terminate in the
 612                                 specified time, it will be terminated
 613                                 forcibly via <constant>SIGTERM</constant>, and after
 614                                 another delay of this time with
 615                                 <constant>SIGKILL</constant> (See
 616                                 <varname>KillMode=</varname>
 617                                 in <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
 618                                 Takes a unit-less value in seconds, or a
 619                                 time span value such as "5min
 620                                 20s". Pass 0 to disable the timeout
 621                                 logic. Defaults to <varname>TimeoutStartSec=</varname> from the
 622                                 manager configuration file.
 623                                 </para></listitem>
 624                         </varlistentry>
 625
 626                         <varlistentry>
 627                                 <term><varname>TimeoutSec=</varname></term>
 628                                 <listitem><para>A shorthand for configuring
 629                                 both <varname>TimeoutStartSec=</varname>
 630                                 and <varname>TimeoutStopSec=</varname>
 631                                 to the specified value.
 632                                 </para></listitem>
 633                         </varlistentry>
 634
 635                         <varlistentry>
 636                                 <term><varname>WatchdogSec=</varname></term>
 637                                 <listitem><para>Configures the
 638                                 watchdog timeout for a service. The
 639                                 watchdog is activated when the start-up is
 640                                 completed. The service must call
 641                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 642                                 regularly with "WATCHDOG=1" (i.e. the
 643                                 "keep-alive ping"). If the time
 644                                 between two such calls is larger than
 645                                 the configured time, then the service
 646                                 is placed in a failure state. By
 647                                 setting <varname>Restart=</varname> to
 648                                 <option>on-failure</option> or
 649                                 <option>always</option>, the service
 650                                 will be automatically restarted. The
 651                                 time configured here will be passed to
 652                                 the executed service process in the
 653                                 <varname>WATCHDOG_USEC=</varname>
 654                                 environment variable. This allows
 655                                 daemons to automatically enable the
 656                                 keep-alive pinging logic if watchdog
 657                                 support is enabled for the service. If
 658                                 this option is used,
 659                                 <varname>NotifyAccess=</varname> (see
 660                                 below) should be set to open access to
 661                                 the notification socket provided by
 662                                 systemd. If
 663                                 <varname>NotifyAccess=</varname> is
 664                                 not set, it will be implicitly set to
 665                                 <option>main</option>. Defaults to 0,
 666                                 which disables this
 667                                 feature.</para></listitem>
 668                         </varlistentry>
 669
 670                         <varlistentry>
 671                                 <term><varname>Restart=</varname></term>
 672                                 <listitem><para>Configures whether the
 673                                 service shall be restarted when the
 674                                 service process exits, is killed,
 675                                 or a timeout is reached. The service
 676                                 process may be the main service
 677                                 process, but also one of the processes
 678                                 specified with
 679                                 <varname>ExecStartPre=</varname>,
 680                                 <varname>ExecStartPost=</varname>,
 681                                 <varname>ExecStopPre=</varname>,
 682                                 <varname>ExecStopPost=</varname>, or
 683                                 <varname>ExecReload=</varname>.
 684                                 When the death of the process is a
 685                                 result of systemd operation (e.g. service
 686                                 stop or restart), the service will not be
 687                                 restarted. Timeouts include missing
 688                                 the watchdog "keep-alive ping"
 689                                 deadline and a service start, reload,
 690                                 and stop operation timeouts.</para>
 691
 692                                 <para>Takes one of
 693                                 <option>no</option>,
 694                                 <option>on-success</option>,
 695                                 <option>on-failure</option>,
 696                                 <option>on-watchdog</option>,
 697                                 <option>on-abort</option>, or
 698                                 <option>always</option>. If set to
 699                                 <option>no</option> (the default), the
 700                                 service will not be restarted. If set to
 701                                 <option>on-success</option>, it will be
 702                                 restarted only when the service process
 703                                 exits cleanly.
 704                                 In this context, a clean exit means
 705                                 an exit code of 0, or one of the signals
 706                                 <constant>SIGHUP</constant>, <constant>SIGINT</constant>, <constant>SIGTERM</constant>, or <constant>SIGPIPE</constant>, and
 707                                 additionally, exit statuses and signals
 708                                 specified in <varname>SuccessExitStatus=</varname>.
 709                                 If set to <option>on-failure</option>,
 710                                 the service will be restarted when the
 711                                 process exits with an nonzero exit code,
 712                                 is terminated by a signal (including on
 713                                 core dump), when an operation (such as
 714                                 service reload) times out, and when the
 715                                 configured watchdog timeout is triggered.
 716                                 If set to
 717                                 <option>on-abort</option>, the service
 718                                 will be restarted only if the service
 719                                 process exits due to an uncaught
 720                                 signal not specified as a clean exit
 721                                 status.
 722                                 If set to
 723                                 <option>on-watchdog</option>, the service
 724                                 will be restarted only if the watchdog
 725                                 timeout for the service expires.
 726                                 If set to
 727                                 <option>always</option>, the service
 728                                 will be restarted regardless of whether
 729                                 it exited cleanly or not, got
 730                                 terminated abnormally by a signal or
 731                                 hit a timeout.</para>
 732
 733                                 <para>In addition to the above settings,
 734                                 the service will not be restarted if the
 735                                 exit code or signal is specified in
 736                                 <varname>RestartPreventExitStatus=</varname>
 737                                 (see below).</para></listitem>
 738                         </varlistentry>
 739
 740                         <varlistentry>
 741                                 <term><varname>SuccessExitStatus=</varname></term>
 742                                 <listitem><para>Takes a list of exit
 743                                 status definitions that when returned
 744                                 by the main service process will be
 745                                 considered successful termination, in
 746                                 addition to the normal successful exit
 747                                 code 0 and the signals <constant>SIGHUP</constant>, <constant>SIGINT</constant>,
 748                                 <constant>SIGTERM</constant>, and <constant>SIGPIPE</constant>. Exit status
 749                                 definitions can either be numeric exit
 750                                 codes or termination signal names,
 751                                 separated by spaces. Signals will only
 752                                 be considered if the service does not implement
 753                                 a signal handler and exits as a direct result
 754                                 of receiving the signal. For example:
 755                                 <programlisting>SuccessExitStatus=1 2 8 <constant>SIGKILL</constant></programlisting>
 756                                 ensures that exit codes 1, 2, 8 and
 757                                 the termination signal
 758                                 <constant>SIGKILL</constant> are
 759                                 considered clean service terminations.
 760                                 </para>
 761
 762                                 <para>Note that if a process has a
 763                                 signal handler installed and exits by
 764                                 calling
 765                                 <citerefentry><refentrytitle>_exit</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 766                                 in response to a signal, the
 767                                 information about the signal is lost.
 768                                 Programs should instead perform cleanup and kill themselves with the same signal instead. See
 769                                 <ulink url="http://www.cons.org/cracauer/sigint.html">Proper handling of SIGINT/SIGQUIT — How to be a proper program</ulink>.</para>
 770
 771                                 <para>This option may appear more than once
 772                                 in which case the list of successful
 773                                 exit statuses is merged. If the empty
 774                                 string is assigned to this option, the
 775                                 list is reset, all prior assignments
 776                                 of this option will have no
 777                                 effect.</para></listitem>
 778                         </varlistentry>
 779
 780                         <varlistentry>
 781                                 <term><varname>RestartPreventExitStatus=</varname></term>
 782                                 <listitem><para>Takes a list of exit
 783                                 status definitions that when returned
 784                                 by the main service process will
 785                                 prevent automatic service restarts
 786                                 regardless of the restart setting
 787                                 configured with
 788                                 <varname>Restart=</varname>. Exit
 789                                 status definitions can either be
 790                                 numeric exit codes or termination
 791                                 signal names, and are separated by
 792                                 spaces. Defaults to the empty list, so
 793                                 that by default no exit status is
 794                                 excluded from the configured restart
 795                                 logic. Example:
 796                                 <literal>RestartPreventExitStatus=1 6
 797                                 SIGABRT</literal>, ensures that exit
 798                                 codes 1 and 6 and the termination
 799                                 signal SIGABRT will not result in
 800                                 automatic service restarting. This
 801                                 option may appear more than once in
 802                                 which case the list of restart preventing
 803                                 statuses is merged. If the empty
 804                                 string is assigned to this option, the
 805                                 list is reset, all prior assignments
 806                                 of this option will have no
 807                                 effect.</para></listitem>
 808                         </varlistentry>
 809
 810                         <varlistentry>
 811                                 <term><varname>PermissionsStartOnly=</varname></term>
 812                                 <listitem><para>Takes a boolean
 813                                 argument. If true, the permission
 814                                 related execution options as
 815                                 configured with
 816                                 <varname>User=</varname> and similar
 817                                 options (see
 818                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 819                                 for more information) are only applied
 820                                 to the process started with
 821                                 <varname>ExecStart=</varname>, and not
 822                                 to the various other
 823                                 <varname>ExecStartPre=</varname>,
 824                                 <varname>ExecStartPost=</varname>,
 825                                 <varname>ExecReload=</varname>,
 826                                 <varname>ExecStop=</varname>,
 827                                 <varname>ExecStopPost=</varname>
 828                                 commands. If false, the setting is
 829                                 applied to all configured commands the
 830                                 same way. Defaults to
 831                                 false.</para></listitem>
 832                         </varlistentry>
 833
 834                         <varlistentry>
 835                                 <term><varname>RootDirectoryStartOnly=</varname></term>
 836                                 <listitem><para>Takes a boolean
 837                                 argument. If true, the root directory
 838                                 as configured with the
 839                                 <varname>RootDirectory=</varname>
 840                                 option (see
 841                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 842                                 for more information) is only applied
 843                                 to the process started with
 844                                 <varname>ExecStart=</varname>, and not
 845                                 to the various other
 846                                 <varname>ExecStartPre=</varname>,
 847                                 <varname>ExecStartPost=</varname>,
 848                                 <varname>ExecReload=</varname>,
 849                                 <varname>ExecStop=</varname>,
 850                                 <varname>ExecStopPost=</varname>
 851                                 commands. If false, the setting is
 852                                 applied to all configured commands the
 853                                 same way. Defaults to
 854                                 false.</para></listitem>
 855                         </varlistentry>
 856
 857                         <varlistentry>
 858                                 <term><varname>NonBlocking=</varname></term>
 859                                 <listitem><para>Set O_NONBLOCK flag
 860                                 for all file descriptors passed via
 861                                 socket-based activation. If true, all
 862                                 file descriptors >= 3 (i.e. all except
 863                                 STDIN/STDOUT/STDERR) will have
 864                                 the O_NONBLOCK flag set and hence are in
 865                                 non-blocking mode. This option is only
 866                                 useful in conjunction with a socket
 867                                 unit, as described in
 868                                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>. Defaults
 869                                 to false.</para></listitem>
 870                         </varlistentry>
 871
 872                         <varlistentry>
 873                                 <term><varname>NotifyAccess=</varname></term>
 874                                 <listitem><para>Controls access to the
 875                                 service status notification socket, as
 876                                 accessible via the
 877                                 <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 878                                 call. Takes one of
 879                                 <option>none</option> (the default),
 880                                 <option>main</option> or
 881                                 <option>all</option>. If
 882                                 <option>none</option>, no daemon status
 883                                 updates are accepted from the service
 884                                 processes, all status update messages
 885                                 are ignored. If <option>main</option>,
 886                                 only service updates sent from the
 887                                 main process of the service are
 888                                 accepted. If <option>all</option>, all
 889                                 services updates from all members of
 890                                 the service's control group are
 891                                 accepted. This option should be set to
 892                                 open access to the notification socket
 893                                 when using
 894                                 <varname>Type=notify</varname> or
 895                                 <varname>WatchdogSec=</varname> (see
 896                                 above). If those options are used but
 897                                 <varname>NotifyAccess=</varname> is not
 898                                 configured, it will be implicitly set
 899                                 to
 900                                 <option>main</option>.</para></listitem>
 901                         </varlistentry>
 902
 903                         <varlistentry>
 904                                 <term><varname>Sockets=</varname></term>
 905                                 <listitem><para>Specifies the name of
 906                                 the socket units this service shall
 907                                 inherit the sockets from when the
 908                                 service is started. Normally it
 909                                 should not be necessary to use this
 910                                 setting as all sockets whose unit
 911                                 shares the same name as the service
 912                                 (ignoring the different suffix of course)
 913                                 are passed to the spawned
 914                                 process.</para>
 915
 916                                 <para>Note that the same socket may be
 917                                 passed to multiple processes at the
 918                                 same time. Also note that a different
 919                                 service may be activated on incoming
 920                                 traffic than inherits the sockets. Or
 921                                 in other words: the
 922                                 <varname>Service=</varname> setting of
 923                                 <filename>.socket</filename> units
 924                                 does not have to match the inverse of
 925                                 the <varname>Sockets=</varname>
 926                                 setting of the
 927                                 <filename>.service</filename> it
 928                                 refers to.</para>
 929
 930                                 <para>This option may appear more than
 931                                 once, in which case the list of socket
 932                                 units is merged. If the empty string
 933                                 is assigned to this option, the list of
 934                                 sockets is reset, all prior uses of
 935                                 this setting will have no
 936                                 effect.</para></listitem>
 937                         </varlistentry>
 938
 939                         <varlistentry>
 940                                 <term><varname>StartLimitInterval=</varname></term>
 941                                 <term><varname>StartLimitBurst=</varname></term>
 942
 943                                 <listitem><para>Configure service
 944                                 start rate limiting. By default,
 945                                 services which are started more often
 946                                 than 5 times within 10s are not
 947                                 permitted to start any more times
 948                                 until the 10s interval ends. With
 949                                 these two options, this rate limiting
 950                                 may be modified. Use
 951                                 <varname>StartLimitInterval=</varname>
 952                                 to configure the checking interval (defaults to
 953                                 <varname>DefaultStartLimitInterval=</varname> in
 954                                 manager configuration file, set to 0 to disable
 955                                 any kind of rate limiting). Use
 956                                 <varname>StartLimitBurst=</varname> to
 957                                 configure how many starts per interval
 958                                 are allowed (defaults to
 959                                 <varname>DefaultStartLimitBurst=</varname> in
 960                                 manager configuration file). These
 961                                 configuration options are particularly
 962                                 useful in conjunction with
 963                                 <varname>Restart=</varname>, however
 964                                 apply to all kinds of starts
 965                                 (including manual), not just those
 966                                 triggered by the
 967                                 <varname>Restart=</varname> logic.
 968                                 Note that units which are configured
 969                                 for <varname>Restart=</varname> and
 970                                 which reach the start limit are not
 971                                 attempted to be restarted anymore,
 972                                 however they may still be restarted
 973                                 manually at a later point from which
 974                                 point on the restart logic is again
 975                                 activated. Note that
 976                                 <command>systemctl
 977                                 reset-failed</command> will cause the
 978                                 restart rate counter for a service to
 979                                 be flushed, which is useful if the
 980                                 administrator wants to manually start
 981                                 a service and the start limit
 982                                 interferes with
 983                                 that.</para></listitem>
 984                         </varlistentry>
 985
 986                         <varlistentry>
 987                                 <term><varname>StartLimitAction=</varname></term>
 988
 989                                 <listitem><para>Configure the action
 990                                 to take if the rate limit configured
 991                                 with
 992                                 <varname>StartLimitInterval=</varname>
 993                                 and
 994                                 <varname>StartLimitBurst=</varname> is
 995                                 hit. Takes one of
 996                                 <option>none</option>,
 997                                 <option>reboot</option>,
 998                                 <option>reboot-force</option> or
 999                                 <option>reboot-immediate</option>. If
1000                                 <option>none</option> is set,
1001                                 hitting the rate limit will trigger no
1002                                 action besides that the start will not
1003                                 be
1004                                 permitted. <option>reboot</option>
1005                                 causes a reboot following the normal
1006                                 shutdown procedure (i.e. equivalent to
1007                                 <command>systemctl reboot</command>),
1008                                 <option>reboot-force</option> causes
1009                                 an forced reboot which will terminate
1010                                 all processes forcibly but should
1011                                 cause no dirty file systems on reboot
1012                                 (i.e. equivalent to <command>systemctl
1013                                 reboot -f</command>) and
1014                                 <option>reboot-immediate</option>
1015                                 causes immediate execution of the
1016                                 <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1017                                 system call, which might result in
1018                                 data loss.  Defaults to
1019                                 <option>none</option>.</para></listitem>
1020                         </varlistentry>
1021
1022                 </variablelist>
1023
1024                 <para>Check
1025                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1026                 and
1027                 <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1028                 for more settings.</para>
1029
1030         </refsect1>
1031
1032         <refsect1>
1033                 <title>Compatibility Options</title>
1034
1035                 <para>The following options are also available in the
1036                 <literal>[Service]</literal> section, but exist purely
1037                 for compatibility reasons and should not be used in
1038                 newly written service files.</para>
1039
1040                 <variablelist class='unit-directives'>
1041                         <varlistentry>
1042                                 <term><varname>SysVStartPriority=</varname></term>
1043                                 <listitem><para>Set the SysV start
1044                                 priority to use to order this service
1045                                 in relation to SysV services lacking
1046                                 LSB headers. This option is only
1047                                 necessary to fix ordering in relation
1048                                 to legacy SysV services, that have no
1049                                 ordering information encoded in the
1050                                 script headers. As such it should only
1051                                 be used as temporary compatibility
1052                                 option, and not be used in new unit
1053                                 files. Almost always it is a better
1054                                 choice to add explicit ordering
1055                                 directives via
1056                                 <varname>After=</varname> or
1057                                 <varname>Before=</varname>,
1058                                 instead. For more details see
1059                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>. If
1060                                 used, pass an integer value in the
1061                                 range 0-99.</para></listitem>
1062                         </varlistentry>
1063
1064                 </variablelist>
1065         </refsect1>
1066
1067         <refsect1>
1068                   <title>See Also</title>
1069                   <para>
1070                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1071                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1072                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1073                           <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1074                           <citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1075                           <citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1076                           <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1077                   </para>
1078         </refsect1>
1079
1080 </refentry>