man/systemd.unit.xml

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   7
   8 <!--
   9   This file is part of systemd.
  10
  11   Copyright 2010 Lennart Poettering
  12
  13   systemd is free software; you can redistribute it and/or modify it
  14   under the terms of the GNU Lesser General Public License as published by
  15   the Free Software Foundation; either version 2.1 of the License, or
  16   (at your option) any later version.
  17
  18   systemd is distributed in the hope that it will be useful, but
  19   WITHOUT ANY WARRANTY; without even the implied warranty of
  20   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  21   Lesser General Public License for more details.
  22
  23   You should have received a copy of the GNU Lesser General Public License
  24   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  25 -->
  26
  27 <refentry id="systemd.unit">
  28
  29         <refentryinfo>
  30                 <title>systemd.unit</title>
  31                 <productname>systemd</productname>
  32
  33                 <authorgroup>
  34                         <author>
  35                                 <contrib>Developer</contrib>
  36                                 <firstname>Lennart</firstname>
  37                                 <surname>Poettering</surname>
  38                                 <email>lennart@poettering.net</email>
  39                         </author>
  40                 </authorgroup>
  41         </refentryinfo>
  42
  43         <refmeta>
  44                 <refentrytitle>systemd.unit</refentrytitle>
  45                 <manvolnum>5</manvolnum>
  46         </refmeta>
  47
  48         <refnamediv>
  49                 <refname>systemd.unit</refname>
  50                 <refpurpose>Unit configuration</refpurpose>
  51         </refnamediv>
  52
  53         <refsynopsisdiv>
  54                 <para><filename><replaceable>service</replaceable>.service</filename>,
  55                 <filename><replaceable>socket</replaceable>.socket</filename>,
  56                 <filename><replaceable>device</replaceable>.device</filename>,
  57                 <filename><replaceable>mount</replaceable>.mount</filename>,
  58                 <filename><replaceable>automount</replaceable>.automount</filename>,
  59                 <filename><replaceable>swap</replaceable>.swap</filename>,
  60                 <filename><replaceable>target</replaceable>.target</filename>,
  61                 <filename><replaceable>path</replaceable>.path</filename>,
  62                 <filename><replaceable>timer</replaceable>.timer</filename>,
  63                 <filename><replaceable>snapshot</replaceable>.snapshot</filename>,
  64                 <filename><replaceable>slice</replaceable>.slice</filename>,
  65                 <filename><replaceable>scope</replaceable>.scope</filename></para>
  66
  67                 <para><literallayout><filename>/etc/systemd/system/*</filename>
  68 <filename>/run/systemd/system/*</filename>
  69 <filename>/usr/lib/systemd/system/*</filename>
  70 <filename>...</filename>
  71                 </literallayout></para>
  72
  73                 <para><literallayout><filename>$XDG_CONFIG_HOME/systemd/user/*</filename>
  74 <filename>$HOME/.config/systemd/user/*</filename>
  75 <filename>/etc/systemd/user/*</filename>
  76 <filename>/run/systemd/user/*</filename>
  77 <filename>$XDG_DATA_HOME/systemd/user/*</filename>
  78 <filename>$HOME/.local/share/systemd/user/*</filename>
  79 <filename>/usr/lib/systemd/user/*</filename>
  80 <filename>...</filename>
  81                 </literallayout></para>
  82         </refsynopsisdiv>
  83
  84         <refsect1>
  85                 <title>Description</title>
  86
  87                 <para>A unit configuration file encodes information
  88                 about a service, a socket, a device, a mount point, an
  89                 automount point, a swap file or partition, a start-up
  90                 target, a watched file system path, a timer controlled
  91                 and supervised by
  92                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  93                 a temporary system state snapshot, a resource
  94                 management slice or a group of externally created
  95                 processes. The syntax is inspired by <ulink
  96                 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
  97                 Desktop Entry Specification</ulink>
  98                 <filename>.desktop</filename> files, which are in turn
  99                 inspired by Microsoft Windows
 100                 <filename>.ini</filename> files.</para>
 101
 102                 <para>This man page lists the common configuration
 103                 options of all the unit types. These options need to
 104                 be configured in the [Unit] or [Install]
 105                 sections of the unit files.</para>
 106
 107                 <para>In addition to the generic [Unit] and [Install]
 108                 sections described here, each unit may have a
 109                 type-specific section, e.g. [Service] for a service
 110                 unit. See the respective man pages for more
 111                 information:
 112                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 113                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 114                 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 115                 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 116                 <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 117                 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 118                 <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 119                 <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 120                 <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 121                 <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 122                 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 123                 <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 124                 </para>
 125
 126                 <para>Various settings are allowed to be specified
 127                 more than once, in which case the interpretation
 128                 depends on the setting. Often, multiple settings form
 129                 a list, and setting to an empty value "resets", which
 130                 means that previous assignments are ignored. When this
 131                 is allowed, it is mentioned in the description of the
 132                 setting. Note that using multiple assignments to the
 133                 same value makes the unit file incompatible with
 134                 parsers for the XDG <filename>.desktop</filename> file
 135                 format.</para>
 136
 137                 <para>Unit files are loaded from a set of paths
 138                 determined during compilation, described in the next section.
 139                 </para>
 140
 141                 <para>Unit files may contain additional options on top
 142                 of those listed here. If systemd encounters an unknown
 143                 option, it will write a warning log message but
 144                 continue loading the unit. If an option or section name
 145                 is prefixed with <option>X-</option>, it is ignored
 146                 completely by systemd. Options within an ignored
 147                 section do not need the prefix. Applications may use
 148                 this to include additional information in the unit
 149                 files.</para>
 150
 151                 <para>Boolean arguments used in unit files can be
 152                 written in various formats. For positive settings the
 153                 strings <option>1</option>, <option>yes</option>,
 154                 <option>true</option> and <option>on</option> are
 155                 equivalent. For negative settings, the strings
 156                 <option>0</option>, <option>no</option>,
 157                 <option>false</option> and <option>off</option> are
 158                 equivalent.</para>
 159
 160                 <para>Time span values encoded in unit files can be
 161                 written in various formats. A stand-alone number
 162                 specifies a time in seconds. If suffixed with a time
 163                 unit, the unit is honored. A concatenation of multiple
 164                 values with units is supported, in which case the
 165                 values are added up. Example: "50" refers to 50
 166                 seconds; "2min 200ms" refers to 2 minutes plus 200
 167                 milliseconds, i.e. 120200ms. The following time units
 168                 are understood: s, min, h, d, w, ms, us. For details
 169                 see
 170                 <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 171
 172                 <para>Empty lines and lines starting with # or ; are
 173                 ignored. This may be used for commenting. Lines ending
 174                 in a backslash are concatenated with the following
 175                 line while reading and the backslash is replaced by a
 176                 space character. This may be used to wrap long lines.</para>
 177
 178                 <para>Along with a unit file
 179                 <filename>foo.service</filename>, the directory
 180                 <filename>foo.service.wants/</filename> may exist. All
 181                 unit files symlinked from such a directory are
 182                 implicitly added as dependencies of type
 183                 <varname>Wanted=</varname> to the unit. This is useful
 184                 to hook units into the start-up of other units,
 185                 without having to modify their unit files. For details
 186                 about the semantics of <varname>Wanted=</varname>, see
 187                 below. The preferred way to create symlinks in the
 188                 <filename>.wants/</filename> directory of a unit file
 189                 is with the <command>enable</command> command of the
 190                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 191                 tool which reads information from the [Install]
 192                 section of unit files (see below). A similar
 193                 functionality exists for <varname>Requires=</varname>
 194                 type dependencies as well, the directory suffix is
 195                 <filename>.requires/</filename> in this case.</para>
 196
 197                 <para>Along with a unit file
 198                 <filename>foo.service</filename>, a directory
 199                 <filename>foo.service.d/</filename> may exist. All
 200                 files with the suffix <literal>.conf</literal> from
 201                 this directory will be parsed after the file itself is
 202                 parsed. This is useful to alter or add configuration
 203                 settings to a unit, without having to modify their
 204                 unit files. Make sure that the file that is included
 205                 has the appropriate section headers before any
 206                 directive.</para>
 207
 208                 <para>Note that while systemd offers a flexible
 209                 dependency system between units it is recommended to
 210                 use this functionality only sparingly and instead rely
 211                 on techniques such as bus-based or socket-based
 212                 activation which make dependencies implicit, resulting
 213                 in a both simpler and more flexible system.</para>
 214
 215                 <para>Some unit names reflect paths existing in the
 216                 file system namespace. Example: a device unit
 217                 <filename>dev-sda.device</filename> refers to a device
 218                 with the device node <filename noindex='true'>/dev/sda</filename> in
 219                 the file system namespace. If this applies, a special
 220                 way to escape the path name is used, so that the
 221                 result is usable as part of a filename. Basically,
 222                 given a path, "/" is replaced by "-", and all
 223                 unprintable characters and the "-" are replaced by
 224                 C-style "\x20" escapes. The root directory "/" is
 225                 encoded as single dash, while otherwise the initial
 226                 and ending "/" is removed from all paths during
 227                 transformation. This escaping is reversible.</para>
 228
 229                 <para>Optionally, units may be instantiated from a
 230                 template file at runtime. This allows creation of
 231                 multiple units from a single configuration file. If
 232                 systemd looks for a unit configuration file, it will
 233                 first search for the literal unit name in the
 234                 file system. If that yields no success and the unit
 235                 name contains an <literal>@</literal> character, systemd will look for a
 236                 unit template that shares the same name but with the
 237                 instance string (i.e. the part between the <literal>@</literal> character
 238                 and the suffix) removed. Example: if a service
 239                 <filename>getty@tty3.service</filename> is requested
 240                 and no file by that name is found, systemd will look
 241                 for <filename>getty@.service</filename> and
 242                 instantiate a service from that configuration file if
 243                 it is found.</para>
 244
 245                 <para>To refer to the instance string from
 246                 within the configuration file you may use the special
 247                 <literal>%i</literal> specifier in many of the
 248                 configuration options. See below for details.</para>
 249
 250                 <para>If a unit file is empty (i.e. has the file size
 251                 0) or is symlinked to <filename>/dev/null</filename>,
 252                 its configuration will not be loaded and it appears
 253                 with a load state of <literal>masked</literal>, and
 254                 cannot be activated. Use this as an effective way to
 255                 fully disable a unit, making it impossible to start it
 256                 even manually.</para>
 257
 258                 <para>The unit file format is covered by the
 259                 <ulink
 260                 url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
 261                 Stability Promise</ulink>.</para>
 262
 263         </refsect1>
 264
 265         <refsect1>
 266                 <title>Unit Load Path</title>
 267
 268                 <para>Unit files are loaded from a set of paths
 269                 determined during compilation, described in the two
 270                 tables below. Unit files found in directories listed
 271                 earlier override files with the same name in
 272                 directories lower in the list.</para>
 273
 274                 <para>When systemd is running in user mode
 275                 (<option>--user</option>) and the variable
 276                 <varname>$SYSTEMD_UNIT_PATH</varname> is set, this
 277                 contents of this variable overrides the unit load
 278                 path.
 279                 </para>
 280
 281                 <table>
 282                   <title>
 283                     Load path when running in system mode (<option>--system</option>).
 284                   </title>
 285
 286                   <tgroup cols='2'>
 287                     <colspec colname='path' />
 288                     <colspec colname='expl' />
 289                     <thead>
 290                       <row>
 291                         <entry>Path</entry>
 292                         <entry>Description</entry>
 293                       </row>
 294                     </thead>
 295                     <tbody>
 296                       <row>
 297                         <entry><filename>/etc/systemd/system</filename></entry>
 298                         <entry>Local configuration</entry>
 299                       </row>
 300                       <row>
 301                         <entry><filename>/run/systemd/system</filename></entry>
 302                         <entry>Runtime units</entry>
 303                       </row>
 304                       <row>
 305                         <entry><filename>/usr/lib/systemd/system</filename></entry>
 306                         <entry>Units of installed packages</entry>
 307                       </row>
 308                     </tbody>
 309                   </tgroup>
 310                 </table>
 311
 312                 <table>
 313                   <title>
 314                     Load path when running in user mode (<option>--user</option>).
 315                   </title>
 316
 317                   <tgroup cols='2'>
 318                     <colspec colname='path' />
 319                     <colspec colname='expl' />
 320                     <thead>
 321                       <row>
 322                         <entry>Path</entry>
 323                         <entry>Description</entry>
 324                       </row>
 325                     </thead>
 326                     <tbody>
 327                       <row>
 328                         <entry><filename>$XDG_CONFIG_HOME/systemd/user</filename></entry>
 329                         <entry>User configuration (only used when $XDG_CONFIG_HOME is set)</entry>
 330                       </row>
 331                       <row>
 332                         <entry><filename>$HOME/.config/systemd/user</filename></entry>
 333                         <entry>User configuration (only used when $XDG_CONFIG_HOME is not set)</entry>
 334                       </row>
 335                       <row>
 336                         <entry><filename>/etc/systemd/user</filename></entry>
 337                         <entry>Local configuration</entry>
 338                       </row>
 339                       <row>
 340                         <entry><filename>/run/systemd/user</filename></entry>
 341                         <entry>Runtime units</entry>
 342                       </row>
 343                       <row>
 344                         <entry><filename>$XDG_DATA_HOME/systemd/user</filename></entry>
 345                         <entry>Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is set)</entry>
 346                       </row>
 347                       <row>
 348                         <entry><filename>$HOME/.local/share/systemd/user</filename></entry>
 349                         <entry>Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is not set)</entry>
 350                       </row>
 351                       <row>
 352                         <entry><filename>/usr/lib/systemd/user</filename></entry>
 353                         <entry>Units of packages that have been installed system-wide</entry>
 354                       </row>
 355                     </tbody>
 356                   </tgroup>
 357                 </table>
 358
 359                 <para>Additional units might be loaded into systemd
 360                 ("linked") from directories not on the unit load
 361                 path. See the <command>link</command> command for
 362                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. Also,
 363                 some units are dynamically created via generators
 364                 <ulink
 365                 url="http://www.freedesktop.org/wiki/Software/systemd/Generators/">Generators</ulink>.
 366                 </para>
 367         </refsect1>
 368
 369         <refsect1>
 370                 <title>[Unit] Section Options</title>
 371
 372                 <para>Unit file may include a [Unit] section, which
 373                 carries generic information about the unit that is not
 374                 dependent on the type of unit:</para>
 375
 376                 <variablelist class='unit-directives'>
 377
 378                         <varlistentry>
 379                                 <term><varname>Description=</varname></term>
 380                                 <listitem><para>A free-form string
 381                                 describing the unit. This is intended
 382                                 for use in UIs to show descriptive
 383                                 information along with the unit
 384                                 name. The description should contain a name
 385                                 that means something to the end user.
 386                                 <literal>Apache2 Web Server</literal> is a good
 387                                 example. Bad examples are
 388                                 <literal>high-performance light-weight HTTP
 389                                 server</literal> (too generic) or
 390                                 <literal>Apache2</literal> (too specific and
 391                                 meaningless for people who do not know
 392                                 Apache).</para></listitem>
 393                         </varlistentry>
 394
 395                         <varlistentry>
 396                                 <term><varname>Documentation=</varname></term>
 397                                 <listitem><para>A space-separated list
 398                                 of URIs referencing documentation for
 399                                 this unit or its
 400                                 configuration. Accepted are only URIs
 401                                 of the types
 402                                 <literal>http://</literal>,
 403                                 <literal>https://</literal>,
 404                                 <literal>file:</literal>,
 405                                 <literal>info:</literal>,
 406                                 <literal>man:</literal>. For more
 407                                 information about the syntax of these
 408                                 URIs, see
 409                                 <citerefentry project='man-pages'><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
 410                                 URIs should be listed in order of
 411                                 relevance, starting with the most
 412                                 relevant. It is a good idea to first
 413                                 reference documentation that explains
 414                                 what the unit's purpose is, followed
 415                                 by how it is configured, followed by
 416                                 any other related documentation. This
 417                                 option may be specified more than once,
 418                                 in which case the specified list of
 419                                 URIs is merged. If the empty string is
 420                                 assigned to this option, the list is
 421                                 reset and all prior assignments will
 422                                 have no effect.</para></listitem>
 423                         </varlistentry>
 424
 425                         <varlistentry>
 426                                 <term><varname>Requires=</varname></term>
 427
 428                                 <listitem><para>Configures requirement
 429                                 dependencies on other units. If this
 430                                 unit gets activated, the units listed
 431                                 here will be activated as well. If one
 432                                 of the other units gets deactivated or
 433                                 its activation fails, this unit will
 434                                 be deactivated. This option may be
 435                                 specified more than once or multiple
 436                                 space-separated units may be specified
 437                                 in one option in which case
 438                                 requirement dependencies for all
 439                                 listed names will be created. Note
 440                                 that requirement dependencies do not
 441                                 influence the order in which services
 442                                 are started or stopped. This has to be
 443                                 configured independently with the
 444                                 <varname>After=</varname> or
 445                                 <varname>Before=</varname> options. If
 446                                 a unit
 447                                 <filename>foo.service</filename>
 448                                 requires a unit
 449                                 <filename>bar.service</filename> as
 450                                 configured with
 451                                 <varname>Requires=</varname> and no
 452                                 ordering is configured with
 453                                 <varname>After=</varname> or
 454                                 <varname>Before=</varname>, then both
 455                                 units will be started simultaneously
 456                                 and without any delay between them if
 457                                 <filename>foo.service</filename> is
 458                                 activated. Often it is a better choice
 459                                 to use <varname>Wants=</varname>
 460                                 instead of
 461                                 <varname>Requires=</varname> in order
 462                                 to achieve a system that is more
 463                                 robust when dealing with failing
 464                                 services.</para>
 465
 466                                 <para>Note that dependencies of this
 467                                 type may also be configured outside of
 468                                 the unit configuration file by
 469                                 adding a symlink to a
 470                                 <filename>.requires/</filename> directory
 471                                 accompanying the unit file. For
 472                                 details see above.</para></listitem>
 473                         </varlistentry>
 474
 475                         <varlistentry>
 476                                 <term><varname>RequiresOverridable=</varname></term>
 477
 478                                 <listitem><para>Similar to
 479                                 <varname>Requires=</varname>.
 480                                 Dependencies listed in
 481                                 <varname>RequiresOverridable=</varname>
 482                                 which cannot be fulfilled or fail to
 483                                 start are ignored if the startup was
 484                                 explicitly requested by the user. If
 485                                 the start-up was pulled in indirectly
 486                                 by some dependency or automatic
 487                                 start-up of units that is not
 488                                 requested by the user, this dependency
 489                                 must be fulfilled and otherwise the
 490                                 transaction fails. Hence, this option
 491                                 may be used to configure dependencies
 492                                 that are normally honored unless the
 493                                 user explicitly starts up the unit, in
 494                                 which case whether they failed or not
 495                                 is irrelevant.</para></listitem>
 496
 497                         </varlistentry>
 498                         <varlistentry>
 499                                 <term><varname>Requisite=</varname></term>
 500                                 <term><varname>RequisiteOverridable=</varname></term>
 501
 502                                 <listitem><para>Similar to
 503                                 <varname>Requires=</varname> and
 504                                 <varname>RequiresOverridable=</varname>,
 505                                 respectively. However, if the units
 506                                 listed here are not started already,
 507                                 they will not be started and the
 508                                 transaction will fail immediately.
 509                                 </para></listitem>
 510                         </varlistentry>
 511
 512                         <varlistentry>
 513                                 <term><varname>Wants=</varname></term>
 514
 515                                 <listitem><para>A weaker version of
 516                                 <varname>Requires=</varname>. Units
 517                                 listed in this option will be started
 518                                 if the configuring unit is. However,
 519                                 if the listed units fail to start
 520                                 or cannot be added to the transaction,
 521                                 this has no impact on the validity of
 522                                 the transaction as a whole. This is
 523                                 the recommended way to hook start-up
 524                                 of one unit to the start-up of another
 525                                 unit.</para>
 526
 527                                 <para>Note that dependencies of this
 528                                 type may also be configured outside of
 529                                 the unit configuration file by adding
 530                                 symlinks to a
 531                                 <filename>.wants/</filename> directory
 532                                 accompanying the unit file. For
 533                                 details, see above.</para></listitem>
 534                         </varlistentry>
 535
 536                         <varlistentry>
 537                                 <term><varname>BindsTo=</varname></term>
 538
 539                                 <listitem><para>Configures requirement
 540                                 dependencies, very similar in style to
 541                                 <varname>Requires=</varname>, however
 542                                 in addition to this behavior, it also
 543                                 declares that this unit is stopped
 544                                 when any of the units listed suddenly
 545                                 disappears. Units can suddenly,
 546                                 unexpectedly disappear if a service
 547                                 terminates on its own choice, a device
 548                                 is unplugged or a mount point
 549                                 unmounted without involvement of
 550                                 systemd.</para></listitem>
 551                         </varlistentry>
 552
 553                         <varlistentry>
 554                                 <term><varname>PartOf=</varname></term>
 555
 556                                 <listitem><para>Configures dependencies
 557                                 similar to <varname>Requires=</varname>,
 558                                 but limited to stopping and restarting
 559                                 of units. When systemd stops or restarts
 560                                 the units listed here, the action is
 561                                 propagated to this unit.
 562                                 Note that this is a one-way dependency —
 563                                 changes to this unit do not affect the
 564                                 listed units.
 565                                 </para></listitem>
 566                         </varlistentry>
 567
 568                         <varlistentry>
 569                                 <term><varname>Conflicts=</varname></term>
 570
 571                                 <listitem><para>A space-separated list
 572                                 of unit names. Configures negative
 573                                 requirement dependencies. If a unit
 574                                 has a <varname>Conflicts=</varname>
 575                                 setting on another unit, starting the
 576                                 former will stop the latter and vice
 577                                 versa. Note that this setting is
 578                                 independent of and orthogonal to the
 579                                 <varname>After=</varname> and
 580                                 <varname>Before=</varname> ordering
 581                                 dependencies.</para>
 582
 583                                 <para>If a unit A that conflicts with
 584                                 a unit B is scheduled to be started at
 585                                 the same time as B, the transaction
 586                                 will either fail (in case both are
 587                                 required part of the transaction) or
 588                                 be modified to be fixed (in case one
 589                                 or both jobs are not a required part
 590                                 of the transaction). In the latter
 591                                 case, the job that is not the required
 592                                 will be removed, or in case both are
 593                                 not required, the unit that conflicts
 594                                 will be started and the unit that is
 595                                 conflicted is
 596                                 stopped.</para></listitem>
 597                         </varlistentry>
 598
 599                         <varlistentry>
 600                                 <term><varname>Before=</varname></term>
 601                                 <term><varname>After=</varname></term>
 602
 603                                 <listitem><para>A space-separated list
 604                                 of unit names. Configures ordering
 605                                 dependencies between units. If a unit
 606                                 <filename>foo.service</filename>
 607                                 contains a setting
 608                                 <option>Before=bar.service</option>
 609                                 and both units are being started,
 610                                 <filename>bar.service</filename>'s
 611                                 start-up is delayed until
 612                                 <filename>foo.service</filename> is
 613                                 started up. Note that this setting is
 614                                 independent of and orthogonal to the
 615                                 requirement dependencies as configured
 616                                 by <varname>Requires=</varname>. It is
 617                                 a common pattern to include a unit
 618                                 name in both the
 619                                 <varname>After=</varname> and
 620                                 <varname>Requires=</varname> option, in
 621                                 which case the unit listed will be
 622                                 started before the unit that is
 623                                 configured with these options. This
 624                                 option may be specified more than
 625                                 once, in which case ordering
 626                                 dependencies for all listed names are
 627                                 created. <varname>After=</varname> is
 628                                 the inverse of
 629                                 <varname>Before=</varname>, i.e. while
 630                                 <varname>After=</varname> ensures that
 631                                 the configured unit is started after
 632                                 the listed unit finished starting up,
 633                                 <varname>Before=</varname> ensures the
 634                                 opposite, i.e.  that the configured
 635                                 unit is fully started up before the
 636                                 listed unit is started. Note that when
 637                                 two units with an ordering dependency
 638                                 between them are shut down, the
 639                                 inverse of the start-up order is
 640                                 applied. i.e. if a unit is configured
 641                                 with <varname>After=</varname> on
 642                                 another unit, the former is stopped
 643                                 before the latter if both are shut
 644                                 down. If one unit with an ordering
 645                                 dependency on another unit is shut
 646                                 down while the latter is started up,
 647                                 the shut down is ordered before the
 648                                 start-up regardless of whether the
 649                                 ordering dependency is actually of
 650                                 type <varname>After=</varname> or
 651                                 <varname>Before=</varname>. If two
 652                                 units have no ordering dependencies
 653                                 between them, they are shut down or
 654                                 started up simultaneously, and no
 655                                 ordering takes
 656                                 place. </para></listitem>
 657                         </varlistentry>
 658
 659                         <varlistentry>
 660                                 <term><varname>OnFailure=</varname></term>
 661
 662                                 <listitem><para>A space-separated list
 663                                 of one or more units that are
 664                                 activated when this unit enters the
 665                                 <literal>failed</literal>
 666                                 state.</para></listitem>
 667                         </varlistentry>
 668
 669                         <varlistentry>
 670                                 <term><varname>PropagatesReloadTo=</varname></term>
 671                                 <term><varname>ReloadPropagatedFrom=</varname></term>
 672
 673                                 <listitem><para>A space-separated list
 674                                 of one or more units where reload
 675                                 requests on this unit will be
 676                                 propagated to, or reload requests on
 677                                 the other unit will be propagated to
 678                                 this unit, respectively. Issuing a
 679                                 reload request on a unit will
 680                                 automatically also enqueue a reload
 681                                 request on all units that the reload
 682                                 request shall be propagated to via
 683                                 these two settings.</para></listitem>
 684                         </varlistentry>
 685
 686                         <varlistentry>
 687                                 <term><varname>JoinsNamespaceOf=</varname></term>
 688
 689                                 <listitem><para>For units that start
 690                                 processes (such as service units),
 691                                 lists one or more other units whose
 692                                 network and/or temporary file
 693                                 namespace to join. This only applies
 694                                 to unit types which support the
 695                                 <varname>PrivateNetwork=</varname> and
 696                                 <varname>PrivateTmp=</varname>
 697                                 directives (see
 698                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 699                                 for details). If a unit that has this
 700                                 setting set is started, its processes
 701                                 will see the same
 702                                 <filename>/tmp</filename>,
 703                                 <filename>/tmp/var</filename> and
 704                                 network namespace as one listed unit
 705                                 that is started. If multiple listed
 706                                 units are already started, it is not
 707                                 defined which namespace is
 708                                 joined. Note that this setting only
 709                                 has an effect if
 710                                 <varname>PrivateNetwork=</varname>
 711                                 and/or <varname>PrivateTmp=</varname>
 712                                 is enabled for both the unit that
 713                                 joins the namespace and the unit whose
 714                                 namespace is joined.</para></listitem>
 715                         </varlistentry>
 716
 717                         <varlistentry>
 718                                 <term><varname>RequiresMountsFor=</varname></term>
 719
 720                                 <listitem><para>Takes a
 721                                 space-separated list of absolute
 722                                 paths. Automatically adds dependencies
 723                                 of type <varname>Requires=</varname>
 724                                 and <varname>After=</varname> for all
 725                                 mount units required to access the
 726                                 specified path.</para>
 727
 728                                 <para>Mount points marked with
 729                                 <option>noauto</option> are not
 730                                 mounted automatically and will be
 731                                 ignored for the purposes of this
 732                                 option. If such a mount should be a
 733                                 requirement for this unit,
 734                                 direct dependencies on the mount
 735                                 units may be added
 736                                 (<varname>Requires=</varname> and
 737                                 <varname>After=</varname> or
 738                                 some other combination).
 739                                 </para></listitem>
 740                         </varlistentry>
 741
 742                         <varlistentry>
 743                                 <term><varname>OnFailureJobMode=</varname></term>
 744
 745                                 <listitem><para>Takes a value of
 746                                 <literal>fail</literal>,
 747                                 <literal>replace</literal>,
 748                                 <literal>replace-irreversibly</literal>,
 749                                 <literal>isolate</literal>,
 750                                 <literal>flush</literal>,
 751                                 <literal>ignore-dependencies</literal>
 752                                 or
 753                                 <literal>ignore-requirements</literal>. Defaults
 754                                 to
 755                                 <literal>replace</literal>. Specifies
 756                                 how the units listed in
 757                                 <varname>OnFailure=</varname> will be
 758                                 enqueued. See
 759                                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 760                                 <option>--job-mode=</option> option
 761                                 for details on the possible values. If
 762                                 this is set to
 763                                 <literal>isolate</literal>, only a
 764                                 single unit may be listed in
 765                                 <varname>OnFailure=</varname>..</para></listitem>
 766                         </varlistentry>
 767
 768                         <varlistentry>
 769                                 <term><varname>IgnoreOnIsolate=</varname></term>
 770
 771                                 <listitem><para>Takes a boolean
 772                                 argument. If <option>true</option>,
 773                                 this unit will not be stopped when
 774                                 isolating another unit. Defaults to
 775                                 <option>false</option>.</para></listitem>
 776                         </varlistentry>
 777
 778                         <varlistentry>
 779                                 <term><varname>IgnoreOnSnapshot=</varname></term>
 780
 781                                 <listitem><para>Takes a boolean
 782                                 argument. If <option>true</option>,
 783                                 this unit will not be included in
 784                                 snapshots. Defaults to
 785                                 <option>true</option> for device and
 786                                 snapshot units, <option>false</option>
 787                                 for the others.</para></listitem>
 788                         </varlistentry>
 789
 790                         <varlistentry>
 791                                 <term><varname>StopWhenUnneeded=</varname></term>
 792
 793                                 <listitem><para>Takes a boolean
 794                                 argument. If <option>true</option>,
 795                                 this unit will be stopped when it is
 796                                 no longer used. Note that in order to
 797                                 minimize the work to be executed,
 798                                 systemd will not stop units by default
 799                                 unless they are conflicting with other
 800                                 units, or the user explicitly
 801                                 requested their shut down. If this
 802                                 option is set, a unit will be
 803                                 automatically cleaned up if no other
 804                                 active unit requires it. Defaults to
 805                                 <option>false</option>.</para></listitem>
 806                         </varlistentry>
 807
 808                         <varlistentry>
 809                                 <term><varname>RefuseManualStart=</varname></term>
 810                                 <term><varname>RefuseManualStop=</varname></term>
 811
 812                                 <listitem><para>Takes a boolean
 813                                 argument. If <option>true</option>,
 814                                 this unit can only be activated
 815                                 or deactivated indirectly. In
 816                                 this case, explicit start-up
 817                                 or termination requested by the
 818                                 user is denied, however if it is
 819                                 started or stopped as a
 820                                 dependency of another unit, start-up
 821                                 or termination will succeed. This
 822                                 is mostly a safety feature to ensure
 823                                 that the user does not accidentally
 824                                 activate units that are not intended
 825                                 to be activated explicitly, and not
 826                                 accidentally deactivate units that are
 827                                 not intended to be deactivated.
 828                                 These options default to
 829                                 <option>false</option>.</para></listitem>
 830                         </varlistentry>
 831
 832                         <varlistentry>
 833                                 <term><varname>AllowIsolate=</varname></term>
 834
 835                                 <listitem><para>Takes a boolean
 836                                 argument. If <option>true</option>,
 837                                 this unit may be used with the
 838                                 <command>systemctl isolate</command>
 839                                 command. Otherwise, this will be
 840                                 refused. It probably is a good idea to
 841                                 leave this disabled except for target
 842                                 units that shall be used similar to
 843                                 runlevels in SysV init systems, just
 844                                 as a precaution to avoid unusable
 845                                 system states. This option defaults to
 846                                 <option>false</option>.</para></listitem>
 847                         </varlistentry>
 848
 849                         <varlistentry>
 850                                 <term><varname>DefaultDependencies=</varname></term>
 851
 852                                 <listitem><para>Takes a boolean
 853                                 argument. If <option>true</option>,
 854                                 (the default), a few default
 855                                 dependencies will implicitly be
 856                                 created for the unit. The actual
 857                                 dependencies created depend on the
 858                                 unit type. For example, for service
 859                                 units, these dependencies ensure that
 860                                 the service is started only after
 861                                 basic system initialization is
 862                                 completed and is properly terminated on
 863                                 system shutdown. See the respective
 864                                 man pages for details. Generally, only
 865                                 services involved with early boot or
 866                                 late shutdown should set this option
 867                                 to <option>false</option>. It is
 868                                 highly recommended to leave this
 869                                 option enabled for the majority of
 870                                 common units. If set to
 871                                 <option>false</option>, this option
 872                                 does not disable all implicit
 873                                 dependencies, just non-essential
 874                                 ones.</para></listitem>
 875                         </varlistentry>
 876
 877                         <varlistentry>
 878                                 <term><varname>JobTimeoutSec=</varname></term>
 879
 880                                 <listitem><para>When clients are
 881                                 waiting for a job of this unit to
 882                                 complete, time out after the specified
 883                                 time. If this time limit is reached,
 884                                 the job will be cancelled, the unit
 885                                 however will not change state or even
 886                                 enter the <literal>failed</literal>
 887                                 mode. This value defaults to 0 (job
 888                                 timeouts disabled), except for device
 889                                 units. NB: this timeout is independent
 890                                 from any unit-specific timeout (for
 891                                 example, the timeout set with
 892                                 <varname>Timeout=</varname> in service
 893                                 units) as the job timeout has no
 894                                 effect on the unit itself, only on the
 895                                 job that might be pending for it. Or
 896                                 in other words: unit-specific timeouts
 897                                 are useful to abort unit state
 898                                 changes, and revert them. The job
 899                                 timeout set with this option however
 900                                 is useful to abort only the job
 901                                 waiting for the unit state to
 902                                 change.</para></listitem>
 903                         </varlistentry>
 904
 905                         <varlistentry>
 906                                 <term><varname>ConditionArchitecture=</varname></term>
 907                                 <term><varname>ConditionVirtualization=</varname></term>
 908                                 <term><varname>ConditionHost=</varname></term>
 909                                 <term><varname>ConditionKernelCommandLine=</varname></term>
 910                                 <term><varname>ConditionSecurity=</varname></term>
 911                                 <term><varname>ConditionCapability=</varname></term>
 912                                 <term><varname>ConditionACPower=</varname></term>
 913                                 <term><varname>ConditionNeedsUpdate=</varname></term>
 914                                 <term><varname>ConditionFirstBoot=</varname></term>
 915                                 <term><varname>ConditionPathExists=</varname></term>
 916                                 <term><varname>ConditionPathExistsGlob=</varname></term>
 917                                 <term><varname>ConditionPathIsDirectory=</varname></term>
 918                                 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
 919                                 <term><varname>ConditionPathIsMountPoint=</varname></term>
 920                                 <term><varname>ConditionPathIsReadWrite=</varname></term>
 921                                 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
 922                                 <term><varname>ConditionFileNotEmpty=</varname></term>
 923                                 <term><varname>ConditionFileIsExecutable=</varname></term>
 924                                 <term><varname>ConditionNull=</varname></term>
 925
 926                                 <listitem><para>Before starting a unit
 927                                 verify that the specified condition is
 928                                 true. If it is not true, the starting
 929                                 of the unit will be skipped, however
 930                                 all ordering dependencies of it are
 931                                 still respected. A failing condition
 932                                 will not result in the unit being
 933                                 moved into a failure state. The
 934                                 condition is checked at the time the
 935                                 queued start job is to be
 936                                 executed.</para>
 937
 938                                 <para><varname>ConditionArchitecture=</varname>
 939                                 may be used to check whether the
 940                                 system is running on a specific
 941                                 architecture. Takes one of
 942                                 <varname>x86</varname>,
 943                                 <varname>x86-64</varname>,
 944                                 <varname>ppc</varname>,
 945                                 <varname>ppc-le</varname>,
 946                                 <varname>ppc64</varname>,
 947                                 <varname>ppc64-le</varname>,
 948                                 <varname>ia64</varname>,
 949                                 <varname>parisc</varname>,
 950                                 <varname>parisc64</varname>,
 951                                 <varname>s390</varname>,
 952                                 <varname>s390x</varname>,
 953                                 <varname>sparc</varname>,
 954                                 <varname>sparc64</varname>,
 955                                 <varname>mips</varname>,
 956                                 <varname>mips-le</varname>,
 957                                 <varname>mips64</varname>,
 958                                 <varname>mips64-le</varname>,
 959                                 <varname>alpha</varname>,
 960                                 <varname>arm</varname>,
 961                                 <varname>arm-be</varname>,
 962                                 <varname>arm64</varname>,
 963                                 <varname>arm64-be</varname>,
 964                                 <varname>sh</varname>,
 965                                 <varname>sh64</varname>,
 966                                 <varname>m86k</varname>,
 967                                 <varname>tilegx</varname>,
 968                                 <varname>cris</varname> to test
 969                                 against a specific architecture. The
 970                                 architecture is determined from the
 971                                 information returned by
 972                                 <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 973                                 and is thus subject to
 974                                 <citerefentry><refentrytitle>personality</refentrytitle><manvolnum>2</manvolnum></citerefentry>. Note
 975                                 that a <varname>Personality=</varname>
 976                                 setting in the same unit file has no
 977                                 effect on this condition. A special
 978                                 architecture name
 979                                 <varname>native</varname> is mapped to
 980                                 the architecture the system manager
 981                                 itself is compiled for. The test may
 982                                 be negated by prepending an
 983                                 exclamation mark.</para>
 984
 985                                 <para><varname>ConditionVirtualization=</varname>
 986                                 may be used to check whether the
 987                                 system is executed in a virtualized
 988                                 environment and optionally test
 989                                 whether it is a specific
 990                                 implementation. Takes either boolean
 991                                 value to check if being executed in
 992                                 any virtualized environment, or one of
 993                                 <varname>vm</varname> and
 994                                 <varname>container</varname> to test
 995                                 against a generic type of
 996                                 virtualization solution, or one of
 997                                 <varname>qemu</varname>,
 998                                 <varname>kvm</varname>,
 999                                 <varname>zvm</varname>,
1000                                 <varname>vmware</varname>,
1001                                 <varname>microsoft</varname>,
1002                                 <varname>oracle</varname>,
1003                                 <varname>xen</varname>,
1004                                 <varname>bochs</varname>,
1005                                 <varname>uml</varname>,
1006                                 <varname>openvz</varname>,
1007                                 <varname>lxc</varname>,
1008                                 <varname>lxc-libvirt</varname>,
1009                                 <varname>systemd-nspawn</varname> to
1010                                 test against a specific
1011                                 implementation. If multiple
1012                                 virtualization technologies are nested,
1013                                 only the innermost is considered. The
1014                                 test may be negated by prepending an
1015                                 exclamation mark.</para>
1016
1017                                 <para><varname>ConditionHost=</varname>
1018                                 may be used to match against the
1019                                 hostname or machine ID of the
1020                                 host. This either takes a hostname
1021                                 string (optionally with shell style
1022                                 globs) which is tested against the
1023                                 locally set hostname as returned by
1024                                 <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
1025                                 or a machine ID formatted as string
1026                                 (see
1027                                 <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
1028                                 The test may be negated by prepending
1029                                 an exclamation mark.</para>
1030
1031                                 <para><varname>ConditionKernelCommandLine=</varname>
1032                                 may be used to check whether a
1033                                 specific kernel command line option is
1034                                 set (or if prefixed with the
1035                                 exclamation mark unset). The argument
1036                                 must either be a single word, or an
1037                                 assignment (i.e. two words, separated
1038                                 <literal>=</literal>). In the former
1039                                 case the kernel command line is
1040                                 searched for the word appearing as is,
1041                                 or as left hand side of an
1042                                 assignment. In the latter case, the
1043                                 exact assignment is looked for with
1044                                 right and left hand side
1045                                 matching.</para>
1046
1047                                 <para><varname>ConditionSecurity=</varname>
1048                                 may be used to check whether the given
1049                                 security module is enabled on the
1050                                 system. Currently the recognized values
1051                                 values are <varname>selinux</varname>,
1052                                 <varname>apparmor</varname>,
1053                                 <varname>ima</varname> and
1054                                 <varname>smack</varname>.
1055                                 The test may be negated by prepending
1056                                 an exclamation
1057                                 mark.</para>
1058
1059                                 <para><varname>ConditionCapability=</varname>
1060                                 may be used to check whether the given
1061                                 capability exists in the capability
1062                                 bounding set of the service manager
1063                                 (i.e. this does not check whether
1064                                 capability is actually available in
1065                                 the permitted or effective sets, see
1066                                 <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1067                                 for details). Pass a capability name
1068                                 such as <literal>CAP_MKNOD</literal>,
1069                                 possibly prefixed with an exclamation
1070                                 mark to negate the check.</para>
1071
1072                                 <para><varname>ConditionACPower=</varname>
1073                                 may be used to check whether the
1074                                 system has AC power, or is exclusively
1075                                 battery powered at the time of
1076                                 activation of the unit. This takes a
1077                                 boolean argument. If set to
1078                                 <varname>true</varname>, the condition
1079                                 will hold only if at least one AC
1080                                 connector of the system is connected
1081                                 to a power source, or if no AC
1082                                 connectors are known. Conversely, if
1083                                 set to <varname>false</varname>, the
1084                                 condition will hold only if there is
1085                                 at least one AC connector known and
1086                                 all AC connectors are disconnected
1087                                 from a power source.</para>
1088
1089                                 <para><varname>ConditionNeedsUpdate=</varname>
1090                                 takes one of <filename>/var</filename>
1091                                 or <filename>/etc</filename> as
1092                                 argument, possibly prefixed with a
1093                                 <literal>!</literal> (for inverting
1094                                 the condition). This condition may be
1095                                 used to conditionalize units on
1096                                 whether the specified directory
1097                                 requires an update because
1098                                 <filename>/usr</filename>'s
1099                                 modification time is newer than the
1100                                 stamp file
1101                                 <filename>.updated</filename> in the
1102                                 specified directory. This is useful to
1103                                 implement offline updates of the
1104                                 vendor operating system resources in
1105                                 <filename>/usr</filename> that require
1106                                 updating of <filename>/etc</filename>
1107                                 or <filename>/var</filename> on the
1108                                 next following boot. Units making use
1109                                 of this condition should order
1110                                 themselves before
1111                                 <citerefentry><refentrytitle>systemd-update-done.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1112                                 to make sure they run before the stamp
1113                                 files's modification time gets reset
1114                                 indicating a completed update.</para>
1115
1116                                 <para><varname>ConditionFirstBoot=</varname>
1117                                 takes a boolean argument. This
1118                                 condition may be used to
1119                                 conditionalize units on whether the
1120                                 system is booting up with an
1121                                 unpopulated <filename>/etc</filename>
1122                                 directory. This may be used to
1123                                 populate <filename>/etc</filename> on
1124                                 the first boot after factory reset, or
1125                                 when a new system instances boots up
1126                                 for the first time.</para>
1127
1128                                 <para>With
1129                                 <varname>ConditionPathExists=</varname>
1130                                 a file existence condition is
1131                                 checked before a unit is started. If
1132                                 the specified absolute path name does
1133                                 not exist, the condition will
1134                                 fail. If the absolute path name passed
1135                                 to
1136                                 <varname>ConditionPathExists=</varname>
1137                                 is prefixed with an exclamation mark
1138                                 (<literal>!</literal>), the test is negated, and the unit
1139                                 is only started if the path does not
1140                                 exist.</para>
1141
1142                                 <para><varname>ConditionPathExistsGlob=</varname>
1143                                 is similar to
1144                                 <varname>ConditionPathExists=</varname>,
1145                                 but checks for the existence of at
1146                                 least one file or directory matching
1147                                 the specified globbing pattern.</para>
1148
1149                                 <para><varname>ConditionPathIsDirectory=</varname>
1150                                 is similar to
1151                                 <varname>ConditionPathExists=</varname>
1152                                 but verifies whether a certain path
1153                                 exists and is a
1154                                 directory.</para>
1155
1156                                 <para><varname>ConditionPathIsSymbolicLink=</varname>
1157                                 is similar to
1158                                 <varname>ConditionPathExists=</varname>
1159                                 but verifies whether a certain path
1160                                 exists and is a symbolic
1161                                 link.</para>
1162
1163                                 <para><varname>ConditionPathIsMountPoint=</varname>
1164                                 is similar to
1165                                 <varname>ConditionPathExists=</varname>
1166                                 but verifies whether a certain path
1167                                 exists and is a mount
1168                                 point.</para>
1169
1170                                 <para><varname>ConditionPathIsReadWrite=</varname>
1171                                 is similar to
1172                                 <varname>ConditionPathExists=</varname>
1173                                 but verifies whether the underlying
1174                                 file system is readable and writable
1175                                 (i.e. not mounted
1176                                 read-only).</para>
1177
1178                                 <para><varname>ConditionDirectoryNotEmpty=</varname>
1179                                 is similar to
1180                                 <varname>ConditionPathExists=</varname>
1181                                 but verifies whether a certain path
1182                                 exists and is a non-empty
1183                                 directory.</para>
1184
1185                                 <para><varname>ConditionFileNotEmpty=</varname>
1186                                 is similar to
1187                                 <varname>ConditionPathExists=</varname>
1188                                 but verifies whether a certain path
1189                                 exists and refers to a regular file
1190                                 with a non-zero size.</para>
1191
1192                                 <para><varname>ConditionFileIsExecutable=</varname>
1193                                 is similar to
1194                                 <varname>ConditionPathExists=</varname>
1195                                 but verifies whether a certain path
1196                                 exists, is a regular file and marked
1197                                 executable.</para>
1198
1199                                 <para>Finally,
1200                                 <varname>ConditionNull=</varname> may
1201                                 be used to add a constant condition
1202                                 check value to the unit. It takes a
1203                                 boolean argument. If set to
1204                                 <varname>false</varname>, the condition
1205                                 will always fail, otherwise
1206                                 succeed.</para>
1207
1208                                 <para>If multiple conditions are
1209                                 specified, the unit will be executed if
1210                                 all of them apply (i.e. a logical AND
1211                                 is applied). Condition checks can be
1212                                 prefixed with a pipe symbol (|) in
1213                                 which case a condition becomes a
1214                                 triggering condition. If at least one
1215                                 triggering condition is defined for a
1216                                 unit, then the unit will be executed if
1217                                 at least one of the triggering
1218                                 conditions apply and all of the
1219                                 non-triggering conditions. If you
1220                                 prefix an argument with the pipe
1221                                 symbol and an exclamation mark, the
1222                                 pipe symbol must be passed first, the
1223                                 exclamation second. Except for
1224                                 <varname>ConditionPathIsSymbolicLink=</varname>,
1225                                 all path checks follow symlinks. If
1226                                 any of these options is assigned the
1227                                 empty string, the list of conditions is
1228                                 reset completely, all previous
1229                                 condition settings (of any kind) will
1230                                 have no effect.</para></listitem>
1231                         </varlistentry>
1232
1233                         <varlistentry>
1234                                 <term><varname>SourcePath=</varname></term>
1235                                 <listitem><para>A path to a
1236                                 configuration file this unit has been
1237                                 generated from. This is primarily
1238                                 useful for implementation of generator
1239                                 tools that convert configuration from
1240                                 an external configuration file format
1241                                 into native unit files. This
1242                                 functionality should not be used in
1243                                 normal units.</para></listitem>
1244                         </varlistentry>
1245                 </variablelist>
1246
1247         </refsect1>
1248
1249         <refsect1>
1250                 <title>[Install] Section Options</title>
1251
1252                 <para>Unit file may include a [Install] section, which
1253                 carries installation information for the unit. This
1254                 section is not interpreted by
1255                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1256                 during runtime. It is used exclusively by the
1257                 <command>enable</command> and
1258                 <command>disable</command> commands of the
1259                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1260                 tool during installation of a unit:</para>
1261
1262                 <variablelist class='unit-directives'>
1263                         <varlistentry>
1264                                 <term><varname>Alias=</varname></term>
1265
1266                                 <listitem><para>A space-seperated list
1267                                 of additional names this unit shall be
1268                                 installed under. The names listed here
1269                                 must have the same suffix (i.e. type)
1270                                 as the unit file name. This option may
1271                                 be specified more than once, in which
1272                                 case all listed names are used. At
1273                                 installation time, <command>systemctl
1274                                 enable</command> will create symlinks
1275                                 from these names to the unit
1276                                 filename.</para></listitem>
1277                         </varlistentry>
1278
1279                         <varlistentry>
1280                                 <term><varname>WantedBy=</varname></term>
1281                                 <term><varname>RequiredBy=</varname></term>
1282
1283                                 <listitem><para>This option may be
1284                                 used more than once, or a
1285                                 space-separated list of unit names may
1286                                 be given. A symbolic link is created
1287                                 in the <filename>.wants/</filename> or
1288                                 <filename>.requires/</filename>
1289                                 directory of each of the listed units
1290                                 when this unit is installed by
1291                                 <command>systemctl enable</command>.
1292                                 This has the effect that a dependency
1293                                 of type <varname>Wants=</varname> or
1294                                 <varname>Requires=</varname> is added
1295                                 from the listed unit to the current
1296                                 unit. The primary result is that the
1297                                 current unit will be started when the
1298                                 listed unit is started. See the
1299                                 description of
1300                                 <varname>Wants=</varname> and
1301                                 <varname>Requires=</varname> in the
1302                                 [Unit] section for details.</para>
1303
1304                                 <para><command>WantedBy=foo.service</command>
1305                                 in a service
1306                                 <filename>bar.service</filename> is
1307                                 mostly equivalent to
1308                                 <command>Alias=foo.service.wants/bar.service</command>
1309                                 in the same file. In case of template
1310                                 units, <command>systemctl enable</command>
1311                                 must be called with an instance name, and
1312                                 this instance will be added to the
1313                                 <filename>.wants/</filename> or
1314                                 <filename>.requires/</filename> list
1315                                 of the listed unit.
1316                                 E.g. <command>WantedBy=getty.target</command>
1317                                 in a service
1318                                 <filename>getty@.service</filename>
1319                                 will result in <command>systemctl
1320                                 enable getty@tty2.service</command>
1321                                 creating a
1322                                 <filename>getty.target.wants/getty@tty2.service</filename>
1323                                 link to <filename>getty@.service</filename>.
1324                                 </para></listitem>
1325                         </varlistentry>
1326
1327                         <varlistentry>
1328                                 <term><varname>Also=</varname></term>
1329
1330                                 <listitem><para>Additional units to
1331                                 install/deinstall when this unit is
1332                                 installed/deinstalled. If the user
1333                                 requests installation/deinstallation
1334                                 of a unit with this option configured,
1335                                 <command>systemctl enable</command>
1336                                 and <command>systemctl
1337                                 disable</command> will automatically
1338                                 install/uninstall units listed in this option as
1339                                 well.</para>
1340
1341                                 <para>This option may be used more
1342                                 than once, or a space-separated list
1343                                 of unit names may be
1344                                 given.</para></listitem>
1345                         </varlistentry>
1346
1347                         <varlistentry>
1348                                 <term><varname>DefaultInstance=</varname></term>
1349
1350                                 <listitem><para>In template unit files,
1351                                 this specifies for which instance the
1352                                 unit shall be enabled if the template
1353                                 is enabled without any explicitly set
1354                                 instance. This option has no effect in
1355                                 non-template unit files. The specified
1356                                 string must be usable as instance
1357                                 identifier.</para></listitem>
1358                         </varlistentry>
1359                 </variablelist>
1360
1361                 <para>The following specifiers are interpreted in the
1362                 Install section: %n, %N, %p, %i, %U, %u, %m, %H, %b, %v.
1363                 For their meaning see the next section.
1364                 </para>
1365         </refsect1>
1366
1367         <refsect1>
1368                 <title>Specifiers</title>
1369
1370                 <para>Many settings resolve specifiers which may be
1371                 used to write generic unit files referring to runtime
1372                 or unit parameters that are replaced when the unit
1373                 files are loaded. The following specifiers are
1374                 understood:</para>
1375
1376                 <table>
1377                   <title>Specifiers available in unit files</title>
1378                   <tgroup cols='3' align='left' colsep='1' rowsep='1'>
1379                     <colspec colname="spec" />
1380                     <colspec colname="mean" />
1381                     <colspec colname="detail" />
1382                     <thead>
1383                       <row>
1384                         <entry>Specifier</entry>
1385                         <entry>Meaning</entry>
1386                         <entry>Details</entry>
1387                       </row>
1388                     </thead>
1389                     <tbody>
1390                       <row>
1391                         <entry><literal>%n</literal></entry>
1392                         <entry>Full unit name</entry>
1393                         <entry></entry>
1394                       </row>
1395                       <row>
1396                         <entry><literal>%N</literal></entry>
1397                         <entry>Unescaped full unit name</entry>
1398                         <entry>Same as <literal>%n</literal>, but with escaping undone</entry>
1399                       </row>
1400                       <row>
1401                         <entry><literal>%p</literal></entry>
1402                         <entry>Prefix name</entry>
1403                         <entry>For instantiated units, this refers to the string before the <literal>@</literal> character of the unit name. For non-instantiated units, this refers to the name of the unit with the type suffix removed.</entry>
1404                       </row>
1405                       <row>
1406                         <entry><literal>%P</literal></entry>
1407                         <entry>Unescaped prefix name</entry>
1408                         <entry>Same as <literal>%p</literal>, but with escaping undone</entry>
1409                       </row>
1410                       <row>
1411                         <entry><literal>%i</literal></entry>
1412                         <entry>Instance name</entry>
1413                         <entry>For instantiated units: this is the string between the <literal>@</literal> character and the suffix of the unit name.</entry>
1414                       </row>
1415                       <row>
1416                         <entry><literal>%I</literal></entry>
1417                         <entry>Unescaped instance name</entry>
1418                         <entry>Same as <literal>%i</literal>, but with escaping undone</entry>
1419                       </row>
1420                       <row>
1421                         <entry><literal>%f</literal></entry>
1422                         <entry>Unescaped filename</entry>
1423                         <entry>This is either the unescaped instance name (if applicable) with <filename>/</filename> prepended (if applicable), or the prefix name prepended with <filename>/</filename>.</entry>
1424                       </row>
1425                       <row>
1426                         <entry><literal>%c</literal></entry>
1427                         <entry>Control group path of the unit</entry>
1428                         <entry>This path does not include the <filename>/sys/fs/cgroup/systemd/</filename> prefix.</entry>
1429                       </row>
1430                       <row>
1431                         <entry><literal>%r</literal></entry>
1432                         <entry>Control group path of the slice the unit is placed in</entry>
1433                         <entry>This usually maps to the parent cgroup path of <literal>%c</literal>.</entry>
1434                       </row>
1435                       <row>
1436                         <entry><literal>%R</literal></entry>
1437                         <entry>Root control group path below which slices and units are placed</entry>
1438                         <entry>For system instances, this resolves to <filename>/</filename>, except in containers, where this maps to the container's root control group path.</entry>
1439                       </row>
1440                       <row>
1441                         <entry><literal>%t</literal></entry>
1442                         <entry>Runtime directory</entry>
1443                         <entry>This is either <filename>/run</filename> (for the system manager) or the path <literal>$XDG_RUNTIME_DIR</literal> resolves to (for user managers).</entry>
1444                       </row>
1445                       <row>
1446                         <entry><literal>%u</literal></entry>
1447                         <entry>User name</entry>
1448                         <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1449                       </row>
1450                       <row>
1451                         <entry><literal>%U</literal></entry>
1452                         <entry>User UID</entry>
1453                         <entry>This is the numeric UID of the configured user of the unit, or (if none is set) the user running the systemd user instance. Note that this specifier is not available for units run by the systemd system instance (as opposed to those run by a systemd user instance), unless the user has been configured as a numeric UID in the first place or the configured user is the root user.</entry>
1454                       </row>
1455                       <row>
1456                         <entry><literal>%h</literal></entry>
1457                         <entry>User home directory</entry>
1458                         <entry>This is the home directory of the configured user of the unit, or (if none is set) the user running the systemd user instance. Similar to <literal>%U</literal>, this specifier is not available for units run by the systemd system instance, unless the configured user is the root user.</entry>
1459                       </row>
1460                       <row>
1461                         <entry><literal>%s</literal></entry>
1462                         <entry>User shell</entry>
1463                         <entry>This is the shell of the configured user of the unit, or (if none is set) the user running the systemd user instance. Similar to <literal>%U</literal>, this specifier is not available for units run by the systemd system instance, unless the configured user is the root user.</entry>
1464                       </row>
1465                       <row>
1466                         <entry><literal>%m</literal></entry>
1467                         <entry>Machine ID</entry>
1468                         <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>
1469                       </row>
1470                       <row>
1471                         <entry><literal>%b</literal></entry>
1472                         <entry>Boot ID</entry>
1473                         <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
1474                       </row>
1475                       <row>
1476                         <entry><literal>%H</literal></entry>
1477                         <entry>Host name</entry>
1478                         <entry>The hostname of the running system at the point in time the unit configuation is loaded.</entry>
1479                       </row>
1480                       <row>
1481                         <entry><literal>%v</literal></entry>
1482                         <entry>Kernel release</entry>
1483                         <entry>Identical to <command>uname -r</command> output</entry>
1484                       </row>
1485                       <row>
1486                         <entry><literal>%%</literal></entry>
1487                         <entry>Single percent sign</entry>
1488                         <entry>Use <literal>%%</literal> in place of <literal>%</literal> to specify a single percent sign.</entry>
1489                       </row>
1490                     </tbody>
1491                   </tgroup>
1492                 </table>
1493         </refsect1>
1494
1495         <refsect1>
1496                 <title>See Also</title>
1497                 <para>
1498                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1499                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1500                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1501                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1502                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1503                         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1504                         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1505                         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1506                         <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1507                         <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1508                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1509                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1510                         <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1511                         <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1512                         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1513                         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1514                         <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1515                         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1516                         <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1517                 </para>
1518         </refsect1>
1519
1520 </refentry>