man/systemd.unit.xml.in

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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   6   This file is part of systemd.
   7
   8   Copyright 2010 Lennart Poettering
   9
  10   systemd is free software; you can redistribute it and/or modify it
  11   under the terms of the GNU Lesser General Public License as published by
  12   the Free Software Foundation; either version 2.1 of the License, or
  13   (at your option) any later version.
  14
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  18   Lesser General Public License for more details.
  19
  20   You should have received a copy of the GNU Lesser General Public License
  21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  22 -->
  23
  24 <refentry id="systemd.unit">
  25
  26         <refentryinfo>
  27                 <title>systemd.unit</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.unit</refentrytitle>
  42                 <manvolnum>5</manvolnum>
  43         </refmeta>
  44
  45         <refnamediv>
  46                 <refname>systemd.unit</refname>
  47                 <refpurpose>Unit configuration</refpurpose>
  48         </refnamediv>
  49
  50         <refsynopsisdiv>
  51                 <para><filename><replaceable>service</replaceable>.service</filename>,
  52                 <filename><replaceable>socket</replaceable>.socket</filename>,
  53                 <filename><replaceable>device</replaceable>.device</filename>,
  54                 <filename><replaceable>mount</replaceable>.mount</filename>,
  55                 <filename><replaceable>automount</replaceable>.automount</filename>,
  56                 <filename><replaceable>swap</replaceable>.swap</filename>,
  57                 <filename><replaceable>target</replaceable>.target</filename>,
  58                 <filename><replaceable>path</replaceable>.path</filename>,
  59                 <filename><replaceable>timer</replaceable>.timer</filename>,
  60                 <filename><replaceable>snapshot</replaceable>.snapshot</filename></para>
  61
  62                 <para><literallayout><filename>/etc/systemd/system/*</filename>
  63 <filename>/run/systemd/system/*</filename>
  64 <filename>/usr/lib/systemd/system/*</filename>
  65 <filename>...</filename>
  66                 </literallayout></para>
  67
  68                 <para><literallayout><filename>/etc/systemd/user/*</filename>
  69 <filename>/run/systemd/user/*</filename>
  70 <filename>/usr/lib/systemd/user/*</filename>
  71 <filename>...</filename>
  72                 </literallayout></para>
  73         </refsynopsisdiv>
  74
  75         <refsect1>
  76                 <title>Description</title>
  77
  78                 <para>A unit configuration file encodes information
  79                 about a service, a socket, a device, a mount point, an
  80                 automount point, a swap file or partition, a start-up
  81                 target, a file system path, or a timer controlled and
  82                 supervised by
  83                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>. The
  84                 syntax is inspired by <ulink
  85                 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
  86                 Desktop Entry Specification</ulink> <filename>.desktop</filename> files, which are in turn
  87                 inspired by Microsoft Windows
  88                 <filename>.ini</filename> files.</para>
  89
  90                 <para>This man page lists the common configuration
  91                 options of all the unit types. These options need to
  92                 be configured in the [Unit] or [Install]
  93                 sections of the unit files.</para>
  94
  95                 <para>In addition to the generic [Unit] and [Install]
  96                 sections described here, each unit may have a
  97                 type-specific section, e.g. [Service] for a service
  98                 unit. See the respective man pages for more
  99                 information:
 100                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 101                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 102                 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 103                 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 104                 <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 105                 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 106                 <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 107                 <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 108                 <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 109                 <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 110                 </para>
 111
 112                 <para>Unit files are loaded from a set of paths
 113                 determined during compilation, described in the next section.
 114                 </para>
 115
 116                 <para>Unit files may contain additional options on top
 117                 of those listed here. If systemd encounters an unknown
 118                 option it will write a warning log message but
 119                 continue loading the unit. If an option is prefixed
 120                 with <option>X-</option> it is ignored completely by
 121                 systemd. Applications may use this to include
 122                 additional information in the unit files.</para>
 123
 124                 <para>Boolean arguments used in unit files can be
 125                 written in various formats. For positive settings the
 126                 strings <option>1</option>, <option>yes</option>,
 127                 <option>true</option> and <option>on</option> are
 128                 equivalent. For negative settings the strings
 129                 <option>0</option>, <option>no</option>,
 130                 <option>false</option> and <option>off</option> are
 131                 equivalent.</para>
 132
 133                 <para>Time span values encoded in unit files can be
 134                 written in various formats. A stand-alone number
 135                 specifies a time in seconds. If suffixed with a time
 136                 unit, the unit is honored. A concatenation of multiple
 137                 values with units is supported, in which case the
 138                 values are added up. Example: "50" refers to 50
 139                 seconds; "2min 200ms" refers to 2 minutes plus 200
 140                 milliseconds, i.e. 120200ms. The following time units
 141                 are understood: s, min, h, d, w, ms, us. For details
 142                 see
 143                 <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 144
 145                 <para>Empty lines and lines starting with # or ; are
 146                 ignored. This may be used for commenting. Lines ending
 147                 in a backslash are concatenated with the following
 148                 line while reading and the backslash is replaced by a
 149                 space character. This may be used to wrap long lines.</para>
 150
 151                 <para>Along with a unit file
 152                 <filename>foo.service</filename> the directory
 153                 <filename>foo.service.wants/</filename> may exist. All
 154                 unit files symlinked from such a directory are
 155                 implicitly added as dependencies of type
 156                 <varname>Wanted=</varname> to the unit. This is useful
 157                 to hook units into the start-up of other units,
 158                 without having to modify their unit files. For details
 159                 about the semantics of <varname>Wanted=</varname> see
 160                 below. The preferred way to create symlinks in the
 161                 <filename>.wants/</filename> directory of a unit file
 162                 is with the <command>enable</command> command of the
 163                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 164                 tool which reads information from the [Install]
 165                 section of unit files (see below). A similar
 166                 functionality exists for <varname>Requires=</varname>
 167                 type dependencies as well, the directory suffix is
 168                 <filename>.requires/</filename> in this case.</para>
 169
 170                 <para>Along with a unit file
 171                 <filename>foo.service</filename> a directory
 172                 <filename>foo.service.d/</filename> may exist. All
 173                 files with the suffix <filename>.conf</filename> from
 174                 this directory will be parsed after the file itself is
 175                 parsed. This is useful to alter or add configuration
 176                 settings to a unit, without having to modify their
 177                 unit files. Make sure that the file that is included
 178                 has the appropriate section headers before any
 179                 directive.</para>
 180
 181                 <para>If a line starts with <option>.include</option>
 182                 followed by a file name, the specified file will be
 183                 parsed at this point. Make sure that the file that is
 184                 included has the appropriate section headers before
 185                 any directives.</para>
 186
 187                 <para>Note that while systemd offers a flexible
 188                 dependency system between units it is recommended to
 189                 use this functionality only sparingly and instead rely
 190                 on techniques such as bus-based or socket-based
 191                 activation which make dependencies implicit, resulting
 192                 in a both simpler and more flexible system.</para>
 193
 194                 <para>Some unit names reflect paths existing in the
 195                 file system name space. Example: a device unit
 196                 <filename>dev-sda.device</filename> refers to a device
 197                 with the device node <filename>/dev/sda</filename> in
 198                 the file system namespace. If this applies a special
 199                 way to escape the path name is used, so that the
 200                 result is usable as part of a file name. Basically,
 201                 given a path, "/" is replaced by "-", and all
 202                 unprintable characters and the "-" are replaced by
 203                 C-style "\x20" escapes. The root directory "/" is
 204                 encoded as single dash, while otherwise the initial
 205                 and ending "/" is removed from all paths during
 206                 transformation. This escaping is reversible.</para>
 207
 208                 <para>Optionally, units may be instantiated from a
 209                 template file at runtime. This allows creation of
 210                 multiple units from a single configuration file. If
 211                 systemd looks for a unit configuration file it will
 212                 first search for the literal unit name in the
 213                 filesystem. If that yields no success and the unit
 214                 name contains an @ character, systemd will look for a
 215                 unit template that shares the same name but with the
 216                 instance string (i.e. the part between the @ character
 217                 and the suffix) removed. Example: if a service
 218                 <filename>getty@tty3.service</filename> is requested
 219                 and no file by that name is found, systemd will look
 220                 for <filename>getty@.service</filename> and
 221                 instantiate a service from that configuration file if
 222                 it is found.</para>
 223
 224                 <para>To refer to the instance string from
 225                 within the configuration file you may use the special
 226                 <literal>%i</literal> specifier in many of the
 227                 configuration options. See below for details.</para>
 228
 229                 <para>If a unit file is empty (i.e. has the file size
 230                 0) or is symlinked to <filename>/dev/null</filename>
 231                 its configuration will not be loaded and it appears
 232                 with a load state of <literal>masked</literal>, and
 233                 cannot be activated. Use this as an effective way to
 234                 fully disable a unit, making it impossible to start it
 235                 even manually.</para>
 236
 237                 <para>The unit file format is covered by the
 238                 <ulink
 239                 url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
 240                 Stability Promise</ulink>.</para>
 241
 242         </refsect1>
 243
 244         <refsect1>
 245                 <title>Unit load path</title>
 246
 247                 <para>Unit files are loaded from a set of paths
 248                 determined during compilation, described in the two
 249                 tables below. Unit files found in directories higher
 250                 in the hierarchy override files with the same name
 251                 lower in the hierarchy, thus allowing overrides.
 252                 </para>
 253
 254                 <para>When systemd is running in session mode
 255                 (<option>--user</option>) and the variable
 256                 <varname>$SYSTEMD_UNIT_PATH</varname> is set, this
 257                 contents of this variable overrides the unit load
 258                 path.
 259                 </para>
 260
 261                 <table>
 262                   <title>
 263                     Load path when running in system mode (<option>--system</option>).
 264                   </title>
 265
 266                   <tgroup cols='2'>
 267                     <colspec colname='path' />
 268                     <colspec colname='expl' />
 269                     <thead>
 270                       <row>
 271                         <entry>Path</entry>
 272                         <entry>Description</entry>
 273                       </row>
 274                     </thead>
 275                     <tbody>
 276                       <row>
 277                         <entry><filename>/run/systemd/generator.early</filename></entry>
 278                         <entry>Generated units</entry>
 279                       </row>
 280                       <row>
 281                         <entry><filename>@SYSTEM_CONFIG_UNIT_PATH@</filename></entry>
 282                         <entry morerows='1'>Local configuration</entry>
 283                       </row>
 284                       <row>
 285                         <entry><filename>/etc/systemd/system</filename></entry>
 286                       </row>
 287                       <row>
 288                         <entry><filename>/run/systemd/systemd</filename></entry>
 289                         <entry>Volatile units</entry>
 290                       </row>
 291                       <row>
 292                         <entry><filename>/run/systemd/generator</filename></entry>
 293                         <entry>Generated units</entry>
 294                       </row>
 295                       <row>
 296                         <entry><filename>/usr/local/lib/systemd/system</filename></entry>
 297                         <entry>Units for local packages</entry>
 298                       </row>
 299                       <row>
 300                         <entry><filename>@systemunitdir@</filename></entry>
 301                         <entry>Systemd package configuration</entry>
 302                       </row>
 303                       <row>
 304                         <entry><filename>/usr/lib/systemd/system</filename></entry>
 305                         <entry morerows='1'>Units for installed packages</entry>
 306                       </row>
 307                       <row>
 308                         <entry><filename>/lib/systemd/system</filename></entry>
 309                       </row>
 310                       <row>
 311                         <entry><filename>/run/systemd/generator.late</filename></entry>
 312                         <entry>Generated units</entry>
 313                       </row>
 314                     </tbody>
 315                   </tgroup>
 316                 </table>
 317
 318                 <table>
 319                   <title>
 320                     Load path when running in session mode (<option>--user</option>).
 321                   </title>
 322
 323                   <tgroup cols='2'>
 324                     <colspec colname='path' />
 325                     <colspec colname='expl' />
 326                     <thead>
 327                       <row>
 328                         <entry>Path</entry>
 329                         <entry>Description</entry>
 330                       </row>
 331                     </thead>
 332                     <tbody>
 333                       <row>
 334                         <entry><filename>/tmp/systemd-generator.early.<replaceable>XXXXXX</replaceable></filename></entry>
 335                         <entry>Generated units</entry>
 336                       </row>
 337                       <row>
 338                         <entry><filename>@USER_CONFIG_UNIT_PATH@</filename></entry>
 339                         <entry morerows='1'>Local configuration</entry>
 340                       </row>
 341                       <row>
 342                         <entry><filename>/etc/systemd/user</filename></entry>
 343                       </row>
 344                       <row>
 345                         <entry><filename>/run/systemd/user</filename></entry>
 346                         <entry>Volatile units</entry>
 347                       </row>
 348                       <row>
 349                         <entry><filename>/tmp/systemd-generator.<replaceable>XXXXXX</replaceable></filename></entry>
 350                         <entry>Generated units</entry>
 351                       </row>
 352                       <row>
 353                         <entry><filename>/usr/local/lib/systemd/user</filename></entry>
 354                         <entry morerows='1'>Units for local packages</entry>
 355                       </row>
 356                       <row>
 357                         <entry><filename>/usr/local/share/systemd/user</filename></entry>
 358                       </row>
 359                       <row>
 360                         <entry><filename>@userunitdir@</filename></entry>
 361                         <entry>Systemd package configuration</entry>
 362                       </row>
 363                       <row>
 364                         <entry><filename>/usr/lib/systemd/user</filename></entry>
 365                         <entry morerows='1'>Units for installed packages</entry>
 366                       </row>
 367                       <row>
 368                         <entry><filename>/usr/share/systemd/user</filename></entry>
 369                       </row>
 370                       <row>
 371                         <entry><filename>/tmp/systemd-generator.late.<replaceable>XXXXXX</replaceable></filename></entry>
 372                         <entry>Generated units</entry>
 373                       </row>
 374                     </tbody>
 375                   </tgroup>
 376                 </table>
 377
 378                 <para>Note: the paths listed above are set at
 379                 compilation time and differ between distributions. The
 380                 "authorative" list is printed by
 381                 <command>systemd</command> at during start and daemon
 382                 reconfiguration.</para>
 383
 384                 <para>Additional units might be loaded into systemd
 385                 ("linked") from directories not on the unit load
 386                 path. See the <command>link</command> command for
 387                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
 388                 </para>
 389         </refsect1>
 390
 391         <refsect1>
 392                 <title>Options</title>
 393
 394                 <para>Unit file may include a [Unit] section, which
 395                 carries generic information about the unit that is not
 396                 dependent on the type of unit:</para>
 397
 398                 <variablelist class='unit-directives'>
 399
 400                         <varlistentry>
 401                                 <term><varname>Description=</varname></term>
 402                                 <listitem><para>A free-form string
 403                                 describing the unit. This is intended
 404                                 for use in UIs to show descriptive
 405                                 information along with the unit
 406                                 name.</para></listitem>
 407                         </varlistentry>
 408
 409                         <varlistentry>
 410                                 <term><varname>Documentation=</varname></term>
 411                                 <listitem><para>A space separated list
 412                                 of URIs referencing documentation for
 413                                 this unit or its
 414                                 configuration. Accepted are only URIs
 415                                 of the types
 416                                 <literal>http://</literal>,
 417                                 <literal>https://</literal>,
 418                                 <literal>file:</literal>,
 419                                 <literal>info:</literal>,
 420                                 <literal>man:</literal>. For more
 421                                 information about the syntax of these
 422                                 URIs see
 423                                 <citerefentry><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
 424                                 URIs should be listed in order of
 425                                 relevance, starting with the most
 426                                 relevant. It is a good idea to first
 427                                 reference documentation that explains
 428                                 what the unit's purpose is, followed
 429                                 by how it is configured, followed by
 430                                 any other related documentation. This
 431                                 option may be specified more than once
 432                                 in which case the specified list of
 433                                 URIs is merged. If the empty string is
 434                                 assigned to this option the list is
 435                                 reset and all prior assignments will
 436                                 have no effect.</para></listitem>
 437                         </varlistentry>
 438
 439                         <varlistentry>
 440                                 <term><varname>Requires=</varname></term>
 441
 442                                 <listitem><para>Configures requirement
 443                                 dependencies on other units. If this
 444                                 unit gets activated, the units listed
 445                                 here will be activated as well. If one
 446                                 of the other units gets deactivated or
 447                                 its activation fails, this unit will
 448                                 be deactivated. This option may be
 449                                 specified more than once, in which
 450                                 case requirement dependencies for all
 451                                 listed names are created. Note that
 452                                 requirement dependencies do not
 453                                 influence the order in which services
 454                                 are started or stopped. This has to be
 455                                 configured independently with the
 456                                 <varname>After=</varname> or
 457                                 <varname>Before=</varname> options. If
 458                                 a unit
 459                                 <filename>foo.service</filename>
 460                                 requires a unit
 461                                 <filename>bar.service</filename> as
 462                                 configured with
 463                                 <varname>Requires=</varname> and no
 464                                 ordering is configured with
 465                                 <varname>After=</varname> or
 466                                 <varname>Before=</varname>, then both
 467                                 units will be started simultaneously
 468                                 and without any delay between them if
 469                                 <filename>foo.service</filename> is
 470                                 activated. Often it is a better choice
 471                                 to use <varname>Wants=</varname>
 472                                 instead of
 473                                 <varname>Requires=</varname> in order
 474                                 to achieve a system that is more
 475                                 robust when dealing with failing
 476                                 services.</para>
 477
 478                                 <para>Note that dependencies of this
 479                                 type may also be configured outside of
 480                                 the unit configuration file by
 481                                 adding a symlink to a
 482                                 <filename>.requires/</filename> directory
 483                                 accompanying the unit file. For
 484                                 details see above.</para></listitem>
 485                         </varlistentry>
 486
 487                         <varlistentry>
 488                                 <term><varname>RequiresOverridable=</varname></term>
 489
 490                                 <listitem><para>Similar to
 491                                 <varname>Requires=</varname>.
 492                                 Dependencies listed in
 493                                 <varname>RequiresOverridable=</varname>
 494                                 which cannot be fulfilled or fail to
 495                                 start are ignored if the startup was
 496                                 explicitly requested by the user. If
 497                                 the start-up was pulled in indirectly
 498                                 by some dependency or automatic
 499                                 start-up of units that is not
 500                                 requested by the user this dependency
 501                                 must be fulfilled and otherwise the
 502                                 transaction fails. Hence, this option
 503                                 may be used to configure dependencies
 504                                 that are normally honored unless the
 505                                 user explicitly starts up the unit, in
 506                                 which case whether they failed or not
 507                                 is irrelevant.</para></listitem>
 508
 509                         </varlistentry>
 510                         <varlistentry>
 511                                 <term><varname>Requisite=</varname></term>
 512                                 <term><varname>RequisiteOverridable=</varname></term>
 513
 514                                 <listitem><para>Similar to
 515                                 <varname>Requires=</varname>
 516                                 and <varname>RequiresOverridable=</varname>, respectively. However,
 517                                 if a unit listed here is not started
 518                                 already it will not be started and the
 519                                 transaction fails
 520                                 immediately.</para></listitem>
 521                         </varlistentry>
 522
 523                         <varlistentry>
 524                                 <term><varname>Wants=</varname></term>
 525
 526                                 <listitem><para>A weaker version of
 527                                 <varname>Requires=</varname>. A unit
 528                                 listed in this option will be started
 529                                 if the configuring unit is. However,
 530                                 if the listed unit fails to start up
 531                                 or cannot be added to the transaction
 532                                 this has no impact on the validity of
 533                                 the transaction as a whole. This is
 534                                 the recommended way to hook start-up
 535                                 of one unit to the start-up of another
 536                                 unit.</para>
 537
 538                                 <para>Note that dependencies of this
 539                                 type may also be configured outside of
 540                                 the unit configuration file by
 541                                 adding a symlink to a
 542                                 <filename>.wants/</filename> directory
 543                                 accompanying the unit file. For
 544                                 details see above.</para></listitem>
 545                         </varlistentry>
 546
 547                         <varlistentry>
 548                                 <term><varname>BindsTo=</varname></term>
 549
 550                                 <listitem><para>Configures requirement
 551                                 dependencies, very similar in style to
 552                                 <varname>Requires=</varname>, however
 553                                 in addition to this behavior it also
 554                                 declares that this unit is stopped
 555                                 when any of the units listed suddenly
 556                                 disappears. Units can suddenly,
 557                                 unexpectedly disappear if a service
 558                                 terminates on its own choice, a device
 559                                 is unplugged or a mount point
 560                                 unmounted without involvement of
 561                                 systemd.</para></listitem>
 562                         </varlistentry>
 563
 564                         <varlistentry>
 565                                 <term><varname>PartOf=</varname></term>
 566
 567                                 <listitem><para>Configures dependencies
 568                                 similar to <varname>Requires=</varname>,
 569                                 but limited to stopping and restarting
 570                                 of units. When systemd stops or restarts
 571                                 the units listed here, the action is
 572                                 propagated to this unit.
 573                                 Note that this is a one way dependency -
 574                                 changes to this unit do not affect the
 575                                 listed units.
 576                                 </para></listitem>
 577                         </varlistentry>
 578
 579                         <varlistentry>
 580                                 <term><varname>Conflicts=</varname></term>
 581
 582                                 <listitem><para>Configures negative
 583                                 requirement dependencies. If a unit
 584                                 has a
 585                                 <varname>Conflicts=</varname> setting
 586                                 on another unit, starting the former
 587                                 will stop the latter and vice
 588                                 versa. Note that this setting is
 589                                 independent of and orthogonal to the
 590                                 <varname>After=</varname> and
 591                                 <varname>Before=</varname> ordering
 592                                 dependencies.</para>
 593
 594                                 <para>If a unit A that conflicts with
 595                                 a unit B is scheduled to be started at
 596                                 the same time as B, the transaction
 597                                 will either fail (in case both are
 598                                 required part of the transaction) or
 599                                 be modified to be fixed (in case one
 600                                 or both jobs are not a required part
 601                                 of the transaction). In the latter
 602                                 case the job that is not the required
 603                                 will be removed, or in case both are
 604                                 not required the unit that conflicts
 605                                 will be started and the unit that is
 606                                 conflicted is
 607                                 stopped.</para></listitem>
 608                         </varlistentry>
 609
 610                         <varlistentry>
 611                                 <term><varname>Before=</varname></term>
 612                                 <term><varname>After=</varname></term>
 613
 614                                 <listitem><para>Configures ordering
 615                                 dependencies between units. If a unit
 616                                 <filename>foo.service</filename>
 617                                 contains a setting
 618                                 <option>Before=bar.service</option>
 619                                 and both units are being started,
 620                                 <filename>bar.service</filename>'s
 621                                 start-up is delayed until
 622                                 <filename>foo.service</filename> is
 623                                 started up. Note that this setting is
 624                                 independent of and orthogonal to the
 625                                 requirement dependencies as configured
 626                                 by <varname>Requires=</varname>. It is
 627                                 a common pattern to include a unit
 628                                 name in both the
 629                                 <varname>After=</varname> and
 630                                 <varname>Requires=</varname> option in
 631                                 which case the unit listed will be
 632                                 started before the unit that is
 633                                 configured with these options. This
 634                                 option may be specified more than
 635                                 once, in which case ordering
 636                                 dependencies for all listed names are
 637                                 created. <varname>After=</varname> is
 638                                 the inverse of
 639                                 <varname>Before=</varname>, i.e. while
 640                                 <varname>After=</varname> ensures that
 641                                 the configured unit is started after
 642                                 the listed unit finished starting up,
 643                                 <varname>Before=</varname> ensures the
 644                                 opposite, i.e.  that the configured
 645                                 unit is fully started up before the
 646                                 listed unit is started. Note that when
 647                                 two units with an ordering dependency
 648                                 between them are shut down, the
 649                                 inverse of the start-up order is
 650                                 applied. i.e. if a unit is configured
 651                                 with <varname>After=</varname> on
 652                                 another unit, the former is stopped
 653                                 before the latter if both are shut
 654                                 down. If one unit with an ordering
 655                                 dependency on another unit is shut
 656                                 down while the latter is started up,
 657                                 the shut down is ordered before the
 658                                 start-up regardless whether the
 659                                 ordering dependency is actually of
 660                                 type <varname>After=</varname> or
 661                                 <varname>Before=</varname>. If two
 662                                 units have no ordering dependencies
 663                                 between them they are shut down
 664                                 or started up simultaneously, and
 665                                 no ordering takes
 666                                 place. </para></listitem>
 667                         </varlistentry>
 668
 669                         <varlistentry>
 670                                 <term><varname>OnFailure=</varname></term>
 671
 672                                 <listitem><para>Lists one or more
 673                                 units that are activated when this
 674                                 unit enters the
 675                                 '<literal>failed</literal>'
 676                                 state.</para></listitem>
 677                         </varlistentry>
 678
 679                         <varlistentry>
 680                                 <term><varname>PropagatesReloadTo=</varname></term>
 681                                 <term><varname>ReloadPropagatedFrom=</varname></term>
 682
 683                                 <listitem><para>Lists one or more
 684                                 units where reload requests on the
 685                                 unit will be propagated to/on the
 686                                 other unit will be propagated
 687                                 from. Issuing a reload request on a
 688                                 unit will automatically also enqueue a
 689                                 reload request on all units that the
 690                                 reload request shall be propagated to
 691                                 via these two
 692                                 settings.</para></listitem>
 693                         </varlistentry>
 694
 695                         <varlistentry>
 696                                 <term><varname>RequiresMountsFor=</varname></term>
 697
 698                                 <listitem><para>Takes a space
 699                                 separated list of absolute paths. Automatically
 700                                 adds dependencies of type
 701                                 <varname>Requires=</varname> and
 702                                 <varname>After=</varname> for all
 703                                 mount units required to access the
 704                                 specified path.</para></listitem>
 705                         </varlistentry>
 706
 707                         <varlistentry>
 708                                 <term><varname>OnFailureIsolate=</varname></term>
 709
 710                                 <listitem><para>Takes a boolean
 711                                 argument. If <option>true</option> the
 712                                 unit listed in
 713                                 <varname>OnFailure=</varname> will be
 714                                 enqueued in isolation mode, i.e. all
 715                                 units that are not its dependency will
 716                                 be stopped. If this is set only a
 717                                 single unit may be listed in
 718                                 <varname>OnFailure=</varname>. Defaults
 719                                 to
 720                                 <option>false</option>.</para></listitem>
 721                         </varlistentry>
 722
 723                         <varlistentry>
 724                                 <term><varname>IgnoreOnIsolate=</varname></term>
 725
 726                                 <listitem><para>Takes a boolean
 727                                 argument. If <option>true</option>
 728                                 this unit will not be stopped when
 729                                 isolating another unit. Defaults to
 730                                 <option>false</option>.</para></listitem>
 731                         </varlistentry>
 732
 733                         <varlistentry>
 734                                 <term><varname>IgnoreOnSnapshot=</varname></term>
 735
 736                                 <listitem><para>Takes a boolean
 737                                 argument. If <option>true</option>
 738                                 this unit will not be included in
 739                                 snapshots. Defaults to
 740                                 <option>true</option> for device and
 741                                 snapshot units, <option>false</option>
 742                                 for the others.</para></listitem>
 743                         </varlistentry>
 744
 745                         <varlistentry>
 746                                 <term><varname>StopWhenUnneeded=</varname></term>
 747
 748                                 <listitem><para>Takes a boolean
 749                                 argument. If <option>true</option>
 750                                 this unit will be stopped when it is
 751                                 no longer used. Note that in order to
 752                                 minimize the work to be executed,
 753                                 systemd will not stop units by default
 754                                 unless they are conflicting with other
 755                                 units, or the user explicitly
 756                                 requested their shut down. If this
 757                                 option is set, a unit will be
 758                                 automatically cleaned up if no other
 759                                 active unit requires it. Defaults to
 760                                 <option>false</option>.</para></listitem>
 761                         </varlistentry>
 762
 763                         <varlistentry>
 764                                 <term><varname>RefuseManualStart=</varname></term>
 765                                 <term><varname>RefuseManualStop=</varname></term>
 766
 767                                 <listitem><para>Takes a boolean
 768                                 argument. If <option>true</option>
 769                                 this unit can only be activated
 770                                 or deactivated indirectly. In
 771                                 this case explicit start-up
 772                                 or termination requested by the
 773                                 user is denied, however if it is
 774                                 started or stopped as a
 775                                 dependency of another unit, start-up
 776                                 or termination will succeed. This
 777                                 is mostly a safety feature to ensure
 778                                 that the user does not accidentally
 779                                 activate units that are not intended
 780                                 to be activated explicitly, and not
 781                                 accidentally deactivate units that are
 782                                 not intended to be deactivated.
 783                                 These options default to
 784                                 <option>false</option>.</para></listitem>
 785                         </varlistentry>
 786
 787                         <varlistentry>
 788                                 <term><varname>AllowIsolate=</varname></term>
 789
 790                                 <listitem><para>Takes a boolean
 791                                 argument. If <option>true</option>
 792                                 this unit may be used with the
 793                                 <command>systemctl isolate</command>
 794                                 command. Otherwise this will be
 795                                 refused. It probably is a good idea to
 796                                 leave this disabled except for target
 797                                 units that shall be used similar to
 798                                 runlevels in SysV init systems, just
 799                                 as a precaution to avoid unusable
 800                                 system states. This option defaults to
 801                                 <option>false</option>.</para></listitem>
 802                         </varlistentry>
 803
 804                         <varlistentry>
 805                                 <term><varname>DefaultDependencies=</varname></term>
 806
 807                                 <listitem><para>Takes a boolean
 808                                 argument. If <option>true</option>
 809                                 (the default), a few default
 810                                 dependencies will implicitly be
 811                                 created for the unit. The actual
 812                                 dependencies created depend on the
 813                                 unit type. For example, for service
 814                                 units, these dependencies ensure that
 815                                 the service is started only after
 816                                 basic system initialization is
 817                                 completed and is properly terminated on
 818                                 system shutdown. See the respective
 819                                 man pages for details. Generally, only
 820                                 services involved with early boot or
 821                                 late shutdown should set this option
 822                                 to <option>false</option>. It is
 823                                 highly recommended to leave this
 824                                 option enabled for the majority of
 825                                 common units. If set to
 826                                 <option>false</option> this option
 827                                 does not disable all implicit
 828                                 dependencies, just non-essential
 829                                 ones.</para></listitem>
 830                         </varlistentry>
 831
 832                         <varlistentry>
 833                                 <term><varname>JobTimeoutSec=</varname></term>
 834
 835                                 <listitem><para>When clients are
 836                                 waiting for a job of this unit to
 837                                 complete, time out after the specified
 838                                 time. If this time limit is reached
 839                                 the job will be cancelled, the unit
 840                                 however will not change state or even
 841                                 enter the '<literal>failed</literal>'
 842                                 mode. This value defaults to 0 (job
 843                                 timeouts disabled), except for device
 844                                 units. NB: this timeout is independent
 845                                 from any unit-specific timeout (for
 846                                 example, the timeout set with
 847                                 <varname>Timeout=</varname> in service
 848                                 units) as the job timeout has no
 849                                 effect on the unit itself, only on the
 850                                 job that might be pending for it. Or
 851                                 in other words: unit-specific timeouts
 852                                 are useful to abort unit state
 853                                 changes, and revert them. The job
 854                                 timeout set with this option however
 855                                 is useful to abort only the job
 856                                 waiting for the unit state to
 857                                 change.</para></listitem>
 858                         </varlistentry>
 859
 860                         <varlistentry>
 861                                 <term><varname>ConditionPathExists=</varname></term>
 862                                 <term><varname>ConditionPathExistsGlob=</varname></term>
 863                                 <term><varname>ConditionPathIsDirectory=</varname></term>
 864                                 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
 865                                 <term><varname>ConditionPathIsMountPoint=</varname></term>
 866                                 <term><varname>ConditionPathIsReadWrite=</varname></term>
 867                                 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
 868                                 <term><varname>ConditionFileNotEmpty=</varname></term>
 869                                 <term><varname>ConditionFileIsExecutable=</varname></term>
 870                                 <term><varname>ConditionKernelCommandLine=</varname></term>
 871                                 <term><varname>ConditionVirtualization=</varname></term>
 872                                 <term><varname>ConditionSecurity=</varname></term>
 873                                 <term><varname>ConditionCapability=</varname></term>
 874                                 <term><varname>ConditionHost=</varname></term>
 875                                 <term><varname>ConditionACPower=</varname></term>
 876                                 <term><varname>ConditionNull=</varname></term>
 877
 878                                 <listitem><para>Before starting a unit
 879                                 verify that the specified condition is
 880                                 true. If it is not true the starting
 881                                 of the unit will be skipped, however
 882                                 all ordering dependencies of it are
 883                                 still respected. A failing condition
 884                                 will not result in the unit being
 885                                 moved into a failure state. The
 886                                 condition is checked at the time the
 887                                 queued start job is to be
 888                                 executed.</para>
 889
 890                                 <para>With
 891                                 <varname>ConditionPathExists=</varname>
 892                                 a file existence condition is
 893                                 checked before a unit is started. If
 894                                 the specified absolute path name does
 895                                 not exist the condition will
 896                                 fail. If the absolute path name passed
 897                                 to
 898                                 <varname>ConditionPathExists=</varname>
 899                                 is prefixed with an exclamation mark
 900                                 ('!'), the test is negated, and the unit
 901                                 is only started if the path does not
 902                                 exist.</para>
 903
 904                                 <para><varname>ConditionPathExistsGlob=</varname>
 905                                 is similar to
 906                                 <varname>ConditionPathExists=</varname>,
 907                                 but checks for the existence of at
 908                                 least one file or directory matching
 909                                 the specified globbing pattern.</para>
 910
 911                                 <para><varname>ConditionPathIsDirectory=</varname>
 912                                 is similar to
 913                                 <varname>ConditionPathExists=</varname>
 914                                 but verifies whether a certain path
 915                                 exists and is a
 916                                 directory.</para>
 917
 918                                 <para><varname>ConditionPathIsSymbolicLink=</varname>
 919                                 is similar to
 920                                 <varname>ConditionPathExists=</varname>
 921                                 but verifies whether a certain path
 922                                 exists and is a symbolic
 923                                 link.</para>
 924
 925                                 <para><varname>ConditionPathIsMountPoint=</varname>
 926                                 is similar to
 927                                 <varname>ConditionPathExists=</varname>
 928                                 but verifies whether a certain path
 929                                 exists and is a mount
 930                                 point.</para>
 931
 932                                 <para><varname>ConditionPathIsReadWrite=</varname>
 933                                 is similar to
 934                                 <varname>ConditionPathExists=</varname>
 935                                 but verifies whether the underlying
 936                                 file system is readable and writable
 937                                 (i.e. not mounted
 938                                 read-only).</para>
 939
 940                                 <para><varname>ConditionDirectoryNotEmpty=</varname>
 941                                 is similar to
 942                                 <varname>ConditionPathExists=</varname>
 943                                 but verifies whether a certain path
 944                                 exists and is a non-empty
 945                                 directory.</para>
 946
 947                                 <para><varname>ConditionFileNotEmpty=</varname>
 948                                 is similar to
 949                                 <varname>ConditionPathExists=</varname>
 950                                 but verifies whether a certain path
 951                                 exists and refers to a regular file
 952                                 with a non-zero size.</para>
 953
 954                                 <para><varname>ConditionFileIsExecutable=</varname>
 955                                 is similar to
 956                                 <varname>ConditionPathExists=</varname>
 957                                 but verifies whether a certain path
 958                                 exists, is a regular file and marked
 959                                 executable.</para>
 960
 961                                 <para>Similar,
 962                                 <varname>ConditionKernelCommandLine=</varname>
 963                                 may be used to check whether a
 964                                 specific kernel command line option is
 965                                 set (or if prefixed with the
 966                                 exclamation mark unset). The argument
 967                                 must either be a single word, or an
 968                                 assignment (i.e. two words, separated
 969                                 '='). In the former
 970                                 case the kernel command line is
 971                                 searched for the word appearing as is,
 972                                 or as left hand side of an
 973                                 assignment. In the latter case the
 974                                 exact assignment is looked for with
 975                                 right and left hand side
 976                                 matching.</para>
 977
 978                                 <para><varname>ConditionVirtualization=</varname>
 979                                 may be used to check whether the
 980                                 system is executed in a virtualized
 981                                 environment and optionally test
 982                                 whether it is a specific
 983                                 implementation. Takes either boolean
 984                                 value to check if being executed in
 985                                 any virtualized environment, or one of
 986                                 <varname>vm</varname> and
 987                                 <varname>container</varname> to test
 988                                 against a generic type of
 989                                 virtualization solution, or one of
 990                                 <varname>qemu</varname>,
 991                                 <varname>kvm</varname>,
 992                                 <varname>vmware</varname>,
 993                                 <varname>microsoft</varname>,
 994                                 <varname>oracle</varname>,
 995                                 <varname>xen</varname>,
 996                                 <varname>bochs</varname>,
 997                                 <varname>chroot</varname>,
 998                                 <varname>openvz</varname>,
 999                                 <varname>lxc</varname>,
1000                                 <varname>lxc-libvirt</varname>,
1001                                 <varname>systemd-nspawn</varname> to
1002                                 test against a specific
1003                                 implementation. If multiple
1004                                 virtualization technologies are nested
1005                                 only the innermost is considered. The
1006                                 test may be negated by prepending an
1007                                 exclamation mark.</para>
1008
1009                                 <para><varname>ConditionSecurity=</varname>
1010                                 may be used to check whether the given
1011                                 security module is enabled on the
1012                                 system.  Currently the only recognized
1013                                 value is <varname>selinux</varname>.
1014                                 The test may be negated by prepending
1015                                 an exclamation
1016                                 mark.</para>
1017
1018                                 <para><varname>ConditionCapability=</varname>
1019                                 may be used to check whether the given
1020                                 capability exists in the capability
1021                                 bounding set of the service manager
1022                                 (i.e. this does not check whether
1023                                 capability is actually available in
1024                                 the permitted or effective sets, see
1025                                 <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1026                                 for details). Pass a capability name
1027                                 such as <literal>CAP_MKNOD</literal>,
1028                                 possibly prefixed with an exclamation
1029                                 mark to negate the check.</para>
1030
1031                                 <para><varname>ConditionHost=</varname>
1032                                 may be used to match against the
1033                                 host name or machine ID of the
1034                                 host. This either takes a host name
1035                                 string (optionally with shell style
1036                                 globs) which is tested against the
1037                                 locally set host name as returned by
1038                                 <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
1039                                 or a machine ID formatted as string
1040                                 (see
1041                                 <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
1042                                 The test may be negated by prepending
1043                                 an exclamation mark.</para>
1044
1045                                 <para><varname>ConditionACPower=</varname>
1046                                 may be used to check whether the
1047                                 system has AC power, or is exclusively
1048                                 battery powered at the time of
1049                                 activation of the unit. This takes a
1050                                 boolean argument. If set to
1051                                 <varname>true</varname> the condition
1052                                 will hold only if at least one AC
1053                                 connector of the system is connected
1054                                 to a power source, or if no AC
1055                                 connectors are known. Conversely, if
1056                                 set to <varname>false</varname> the
1057                                 condition will hold only if there is
1058                                 at least one AC connector known and
1059                                 all AC connectors are disconnected
1060                                 from a power source.</para>
1061
1062                                 <para>Finally,
1063                                 <varname>ConditionNull=</varname> may
1064                                 be used to add a constant condition
1065                                 check value to the unit. It takes a
1066                                 boolean argument. If set to
1067                                 <varname>false</varname> the condition
1068                                 will always fail, otherwise
1069                                 succeed.</para>
1070
1071                                 <para>If multiple conditions are
1072                                 specified the unit will be executed if
1073                                 all of them apply (i.e. a logical AND
1074                                 is applied). Condition checks can be
1075                                 prefixed with a pipe symbol (|) in
1076                                 which case a condition becomes a
1077                                 triggering condition. If at least one
1078                                 triggering condition is defined for a
1079                                 unit then the unit will be executed if
1080                                 at least one of the triggering
1081                                 conditions apply and all of the
1082                                 non-triggering conditions. If you
1083                                 prefix an argument with the pipe
1084                                 symbol and an exclamation mark the
1085                                 pipe symbol must be passed first, the
1086                                 exclamation second. Except for
1087                                 <varname>ConditionPathIsSymbolicLink=</varname>,
1088                                 all path checks follow symlinks. If
1089                                 any of these options is assigned the
1090                                 empty string the list of conditions is
1091                                 reset completely, all previous
1092                                 condition settings (of any kind) will
1093                                 have no effect.</para></listitem>
1094                         </varlistentry>
1095
1096                         <varlistentry>
1097                                 <term><varname>SourcePath=</varname></term>
1098                                 <listitem><para>A path to a
1099                                 configuration file this unit has been
1100                                 generated from. This is primarily
1101                                 useful for implementation of generator
1102                                 tools that convert configuration from
1103                                 an external configuration file format
1104                                 into native unit files. Thus
1105                                 functionality should not be used in
1106                                 normal units.</para></listitem>
1107                         </varlistentry>
1108                 </variablelist>
1109
1110                 <para>Unit file may include a [Install] section, which
1111                 carries installation information for the unit. This
1112                 section is not interpreted by
1113                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1114                 during runtime. It is used exclusively by the
1115                 <command>enable</command> and
1116                 <command>disable</command> commands of the
1117                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1118                 tool during installation of a unit:</para>
1119
1120                 <variablelist class='unit-directives'>
1121                         <varlistentry>
1122                                 <term><varname>Alias=</varname></term>
1123
1124                                 <listitem><para>Additional names this
1125                                 unit shall be installed under. The
1126                                 names listed here must have the same
1127                                 suffix (i.e. type) as the unit file
1128                                 name. This option may be specified
1129                                 more than once, in which case all
1130                                 listed names are used. At installation
1131                                 time,
1132                                 <command>systemctl enable</command>
1133                                 will create symlinks from these names
1134                                 to the unit file name.</para></listitem>
1135                         </varlistentry>
1136
1137                         <varlistentry>
1138                                 <term><varname>WantedBy=</varname></term>
1139                                 <term><varname>RequiredBy=</varname></term>
1140
1141                                 <listitem><para>Installs a symlink in
1142                                 the <filename>.wants/</filename>
1143                                 or <filename>.requires/</filename>
1144                                 subdirectory for a unit, respectively. This has the
1145                                 effect that when the listed unit name
1146                                 is activated the unit listing it is
1147                                 activated
1148                                 too. <command>WantedBy=foo.service</command>
1149                                 in a service
1150                                 <filename>bar.service</filename> is
1151                                 mostly equivalent to
1152                                 <command>Alias=foo.service.wants/bar.service</command>
1153                                 in the same file.</para></listitem>
1154                         </varlistentry>
1155
1156                         <varlistentry>
1157                                 <term><varname>Also=</varname></term>
1158
1159                                 <listitem><para>Additional units to
1160                                 install when this unit is
1161                                 installed. If the user requests
1162                                 installation of a unit with this
1163                                 option configured,
1164                                 <command>systemctl enable</command>
1165                                 will automatically install units
1166                                 listed in this option as
1167                                 well.</para></listitem>
1168                         </varlistentry>
1169                 </variablelist>
1170
1171                 <para>The following specifiers are interpreted in the
1172                 Install section: %n, %N, %p, %i, %U, %u, %m, %H, %b.
1173                 For their meaning see the next section.
1174                 </para>
1175         </refsect1>
1176
1177         <refsect1>
1178                 <title>Specifiers</title>
1179
1180                 <para>Many settings resolve specifiers which may be
1181                 used to write generic unit files referring to runtime
1182                 or unit parameters that are replaced when the unit
1183                 files are loaded. The following specifiers are
1184                 understood:</para>
1185
1186                 <table>
1187                   <title>Specifiers available in unit files</title>
1188                   <tgroup cols='3' align='left' colsep='1' rowsep='1'>
1189                     <colspec colname="spec" />
1190                     <colspec colname="mean" />
1191                     <colspec colname="detail" />
1192                     <thead>
1193                       <row>
1194                         <entry>Specifier</entry>
1195                         <entry>Meaning</entry>
1196                         <entry>Details</entry>
1197                       </row>
1198                     </thead>
1199                     <tbody>
1200                       <row>
1201                         <entry><literal>%n</literal></entry>
1202                         <entry>Full unit name</entry>
1203                         <entry></entry>
1204                       </row>
1205                       <row>
1206                         <entry><literal>%N</literal></entry>
1207                         <entry>Unescaped full unit name</entry>
1208                         <entry></entry>
1209                       </row>
1210                       <row>
1211                         <entry><literal>%p</literal></entry>
1212                         <entry>Prefix name</entry>
1213                         <entry>For instantiated units this refers to the string before the @. For non-instantiated units this refers to to the name of the unit with the type suffix removed.</entry>
1214                       </row>
1215                       <row>
1216                         <entry><literal>%P</literal></entry>
1217                         <entry>Unescaped prefix name</entry>
1218                         <entry></entry>
1219                       </row>
1220                       <row>
1221                         <entry><literal>%i</literal></entry>
1222                         <entry>Instance name</entry>
1223                         <entry>For instantiated units: this is the string between the @ character and the suffix.</entry>
1224                       </row>
1225                       <row>
1226                         <entry><literal>%I</literal></entry>
1227                         <entry>Unescaped instance name</entry>
1228                         <entry></entry>
1229                       </row>
1230                       <row>
1231                         <entry><literal>%f</literal></entry>
1232                         <entry>Unescaped file name</entry>
1233                         <entry>This is either the unescaped instance name (if applicable) with / prepended (if applicable), or the prefix name similarly prepended with /.</entry>
1234                       </row>
1235                       <row>
1236                         <entry><literal>%c</literal></entry>
1237                         <entry>Control group path of the unit</entry>
1238                         <entry></entry>
1239                       </row>
1240                       <row>
1241                         <entry><literal>%r</literal></entry>
1242                         <entry>Root control group path of systemd</entry>
1243                         <entry></entry>
1244                       </row>
1245                       <row>
1246                         <entry><literal>%R</literal></entry>
1247                         <entry>Parent directory of the root control group path of systemd</entry>
1248                         <entry></entry>
1249                       </row>
1250                       <row>
1251                         <entry><literal>%t</literal></entry>
1252                         <entry>Runtime socket dir</entry>
1253                         <entry>This is either <filename>/run</filename> (for the system manager) or <literal>$XDG_RUNTIME_DIR</literal> (for user managers).</entry>
1254                       </row>
1255                       <row>
1256                         <entry><literal>%u</literal></entry>
1257                         <entry>User name</entry>
1258                         <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1259                       </row>
1260                       <row>
1261                         <entry><literal>%U</literal></entry>
1262                         <entry>User UID</entry>
1263                         <entry>This is the UID of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1264                       </row>
1265                       <row>
1266                         <entry><literal>%h</literal></entry>
1267                         <entry>User home directory</entry>
1268                         <entry>This is the home directory of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1269                       </row>
1270                       <row>
1271                         <entry><literal>%s</literal></entry>
1272                         <entry>User shell</entry>
1273                         <entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1274                       </row>
1275                       <row>
1276                         <entry><literal>%m</literal></entry>
1277                         <entry>Machine ID</entry>
1278                         <entry>The machine ID of the running system, formatted as string. See <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry> for more information.</entry>
1279                       </row>
1280                       <row>
1281                         <entry><literal>%b</literal></entry>
1282                         <entry>Boot ID</entry>
1283                         <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
1284                       </row>
1285                       <row>
1286                         <entry><literal>%H</literal></entry>
1287                         <entry>Host name</entry>
1288                         <entry>The host name of the running system.</entry>
1289                       </row>
1290                     </tbody>
1291                   </tgroup>
1292                 </table>
1293         </refsect1>
1294
1295         <refsect1>
1296                 <title>See Also</title>
1297                 <para>
1298                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1299                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1300                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1301                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1302                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1303                         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1304                         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1305                         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1306                         <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1307                         <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1308                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1309                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1310                         <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1311                         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1312                         <citerefentry><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1313                         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1314                 </para>
1315         </refsect1>
1316
1317 </refentry>