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