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>$SYSTEMD_UNIT_PATH</varname> is set, this
 277                 contents of this variable overrides the unit load
 278                 path. If <varname>$SYSTEMD_UNIT_PATH</varname> ends
 279                 with an empty component (<literal>:</literal>), the
 280                 usual unit load path will be appended to the contents
 281                 of the variable.</para>
 282
 283                 <table>
 284                   <title>
 285                     Load path when running in system mode (<option>--system</option>).
 286                   </title>
 287
 288                   <tgroup cols='2'>
 289                     <colspec colname='path' />
 290                     <colspec colname='expl' />
 291                     <thead>
 292                       <row>
 293                         <entry>Path</entry>
 294                         <entry>Description</entry>
 295                       </row>
 296                     </thead>
 297                     <tbody>
 298                       <row>
 299                         <entry><filename>/etc/systemd/system</filename></entry>
 300                         <entry>Local configuration</entry>
 301                       </row>
 302                       <row>
 303                         <entry><filename>/run/systemd/system</filename></entry>
 304                         <entry>Runtime units</entry>
 305                       </row>
 306                       <row>
 307                         <entry><filename>/usr/lib/systemd/system</filename></entry>
 308                         <entry>Units of installed packages</entry>
 309                       </row>
 310                     </tbody>
 311                   </tgroup>
 312                 </table>
 313
 314                 <table>
 315                   <title>
 316                     Load path when running in user mode (<option>--user</option>).
 317                   </title>
 318
 319                   <tgroup cols='2'>
 320                     <colspec colname='path' />
 321                     <colspec colname='expl' />
 322                     <thead>
 323                       <row>
 324                         <entry>Path</entry>
 325                         <entry>Description</entry>
 326                       </row>
 327                     </thead>
 328                     <tbody>
 329                       <row>
 330                         <entry><filename>$XDG_CONFIG_HOME/systemd/user</filename></entry>
 331                         <entry>User configuration (only used when $XDG_CONFIG_HOME is set)</entry>
 332                       </row>
 333                       <row>
 334                         <entry><filename>$HOME/.config/systemd/user</filename></entry>
 335                         <entry>User configuration (only used when $XDG_CONFIG_HOME is not set)</entry>
 336                       </row>
 337                       <row>
 338                         <entry><filename>/etc/systemd/user</filename></entry>
 339                         <entry>Local configuration</entry>
 340                       </row>
 341                       <row>
 342                         <entry><filename>/run/systemd/user</filename></entry>
 343                         <entry>Runtime units</entry>
 344                       </row>
 345                       <row>
 346                         <entry><filename>$XDG_DATA_HOME/systemd/user</filename></entry>
 347                         <entry>Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is set)</entry>
 348                       </row>
 349                       <row>
 350                         <entry><filename>$HOME/.local/share/systemd/user</filename></entry>
 351                         <entry>Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is not set)</entry>
 352                       </row>
 353                       <row>
 354                         <entry><filename>/usr/lib/systemd/user</filename></entry>
 355                         <entry>Units of packages that have been installed system-wide</entry>
 356                       </row>
 357                     </tbody>
 358                   </tgroup>
 359                 </table>
 360
 361                 <para>Additional units might be loaded into systemd
 362                 ("linked") from directories not on the unit load
 363                 path. See the <command>link</command> command for
 364                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. Also,
 365                 some units are dynamically created via generators
 366                 <ulink
 367                 url="http://www.freedesktop.org/wiki/Software/systemd/Generators/">Generators</ulink>.
 368                 </para>
 369         </refsect1>
 370
 371         <refsect1>
 372                 <title>[Unit] Section Options</title>
 373
 374                 <para>Unit file may include a [Unit] section, which
 375                 carries generic information about the unit that is not
 376                 dependent on the type of unit:</para>
 377
 378                 <variablelist class='unit-directives'>
 379
 380                         <varlistentry>
 381                                 <term><varname>Description=</varname></term>
 382                                 <listitem><para>A free-form string
 383                                 describing the unit. This is intended
 384                                 for use in UIs to show descriptive
 385                                 information along with the unit
 386                                 name. The description should contain a name
 387                                 that means something to the end user.
 388                                 <literal>Apache2 Web Server</literal> is a good
 389                                 example. Bad examples are
 390                                 <literal>high-performance light-weight HTTP
 391                                 server</literal> (too generic) or
 392                                 <literal>Apache2</literal> (too specific and
 393                                 meaningless for people who do not know
 394                                 Apache).</para></listitem>
 395                         </varlistentry>
 396
 397                         <varlistentry>
 398                                 <term><varname>Documentation=</varname></term>
 399                                 <listitem><para>A space-separated list
 400                                 of URIs referencing documentation for
 401                                 this unit or its
 402                                 configuration. Accepted are only URIs
 403                                 of the types
 404                                 <literal>http://</literal>,
 405                                 <literal>https://</literal>,
 406                                 <literal>file:</literal>,
 407                                 <literal>info:</literal>,
 408                                 <literal>man:</literal>. For more
 409                                 information about the syntax of these
 410                                 URIs, see
 411                                 <citerefentry project='man-pages'><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
 412                                 URIs should be listed in order of
 413                                 relevance, starting with the most
 414                                 relevant. It is a good idea to first
 415                                 reference documentation that explains
 416                                 what the unit's purpose is, followed
 417                                 by how it is configured, followed by
 418                                 any other related documentation. This
 419                                 option may be specified more than once,
 420                                 in which case the specified list of
 421                                 URIs is merged. If the empty string is
 422                                 assigned to this option, the list is
 423                                 reset and all prior assignments will
 424                                 have no effect.</para></listitem>
 425                         </varlistentry>
 426
 427                         <varlistentry>
 428                                 <term><varname>Requires=</varname></term>
 429
 430                                 <listitem><para>Configures requirement
 431                                 dependencies on other units. If this
 432                                 unit gets activated, the units listed
 433                                 here will be activated as well. If one
 434                                 of the other units gets deactivated or
 435                                 its activation fails, this unit will
 436                                 be deactivated. This option may be
 437                                 specified more than once or multiple
 438                                 space-separated units may be specified
 439                                 in one option in which case
 440                                 requirement dependencies for all
 441                                 listed names will be created. Note
 442                                 that requirement dependencies do not
 443                                 influence the order in which services
 444                                 are started or stopped. This has to be
 445                                 configured independently with the
 446                                 <varname>After=</varname> or
 447                                 <varname>Before=</varname> options. If
 448                                 a unit
 449                                 <filename>foo.service</filename>
 450                                 requires a unit
 451                                 <filename>bar.service</filename> as
 452                                 configured with
 453                                 <varname>Requires=</varname> and no
 454                                 ordering is configured with
 455                                 <varname>After=</varname> or
 456                                 <varname>Before=</varname>, then both
 457                                 units will be started simultaneously
 458                                 and without any delay between them if
 459                                 <filename>foo.service</filename> is
 460                                 activated. Often it is a better choice
 461                                 to use <varname>Wants=</varname>
 462                                 instead of
 463                                 <varname>Requires=</varname> in order
 464                                 to achieve a system that is more
 465                                 robust when dealing with failing
 466                                 services.</para>
 467
 468                                 <para>Note that dependencies of this
 469                                 type may also be configured outside of
 470                                 the unit configuration file by
 471                                 adding a symlink to a
 472                                 <filename>.requires/</filename> directory
 473                                 accompanying the unit file. For
 474                                 details see above.</para></listitem>
 475                         </varlistentry>
 476
 477                         <varlistentry>
 478                                 <term><varname>RequiresOverridable=</varname></term>
 479
 480                                 <listitem><para>Similar to
 481                                 <varname>Requires=</varname>.
 482                                 Dependencies listed in
 483                                 <varname>RequiresOverridable=</varname>
 484                                 which cannot be fulfilled or fail to
 485                                 start are ignored if the startup was
 486                                 explicitly requested by the user. If
 487                                 the start-up was pulled in indirectly
 488                                 by some dependency or automatic
 489                                 start-up of units that is not
 490                                 requested by the user, this dependency
 491                                 must be fulfilled and otherwise the
 492                                 transaction fails. Hence, this option
 493                                 may be used to configure dependencies
 494                                 that are normally honored unless the
 495                                 user explicitly starts up the unit, in
 496                                 which case whether they failed or not
 497                                 is irrelevant.</para></listitem>
 498
 499                         </varlistentry>
 500                         <varlistentry>
 501                                 <term><varname>Requisite=</varname></term>
 502                                 <term><varname>RequisiteOverridable=</varname></term>
 503
 504                                 <listitem><para>Similar to
 505                                 <varname>Requires=</varname> and
 506                                 <varname>RequiresOverridable=</varname>,
 507                                 respectively. However, if the units
 508                                 listed here are not started already,
 509                                 they will not be started and the
 510                                 transaction will fail immediately.
 511                                 </para></listitem>
 512                         </varlistentry>
 513
 514                         <varlistentry>
 515                                 <term><varname>Wants=</varname></term>
 516
 517                                 <listitem><para>A weaker version of
 518                                 <varname>Requires=</varname>. Units
 519                                 listed in this option will be started
 520                                 if the configuring unit is. However,
 521                                 if the listed units fail to start
 522                                 or cannot be added to the transaction,
 523                                 this has no impact on the validity of
 524                                 the transaction as a whole. This is
 525                                 the recommended way to hook start-up
 526                                 of one unit to the start-up of another
 527                                 unit.</para>
 528
 529                                 <para>Note that dependencies of this
 530                                 type may also be configured outside of
 531                                 the unit configuration file by adding
 532                                 symlinks to a
 533                                 <filename>.wants/</filename> directory
 534                                 accompanying the unit file. For
 535                                 details, see above.</para></listitem>
 536                         </varlistentry>
 537
 538                         <varlistentry>
 539                                 <term><varname>BindsTo=</varname></term>
 540
 541                                 <listitem><para>Configures requirement
 542                                 dependencies, very similar in style to
 543                                 <varname>Requires=</varname>, however
 544                                 in addition to this behavior, it also
 545                                 declares that this unit is stopped
 546                                 when any of the units listed suddenly
 547                                 disappears. Units can suddenly,
 548                                 unexpectedly disappear if a service
 549                                 terminates on its own choice, a device
 550                                 is unplugged or a mount point
 551                                 unmounted without involvement of
 552                                 systemd.</para></listitem>
 553                         </varlistentry>
 554
 555                         <varlistentry>
 556                                 <term><varname>PartOf=</varname></term>
 557
 558                                 <listitem><para>Configures dependencies
 559                                 similar to <varname>Requires=</varname>,
 560                                 but limited to stopping and restarting
 561                                 of units. When systemd stops or restarts
 562                                 the units listed here, the action is
 563                                 propagated to this unit.
 564                                 Note that this is a one-way dependency —
 565                                 changes to this unit do not affect the
 566                                 listed units.
 567                                 </para></listitem>
 568                         </varlistentry>
 569
 570                         <varlistentry>
 571                                 <term><varname>Conflicts=</varname></term>
 572
 573                                 <listitem><para>A space-separated list
 574                                 of unit names. Configures negative
 575                                 requirement dependencies. If a unit
 576                                 has a <varname>Conflicts=</varname>
 577                                 setting on another unit, starting the
 578                                 former will stop the latter and vice
 579                                 versa. Note that this setting is
 580                                 independent of and orthogonal to the
 581                                 <varname>After=</varname> and
 582                                 <varname>Before=</varname> ordering
 583                                 dependencies.</para>
 584
 585                                 <para>If a unit A that conflicts with
 586                                 a unit B is scheduled to be started at
 587                                 the same time as B, the transaction
 588                                 will either fail (in case both are
 589                                 required part of the transaction) or
 590                                 be modified to be fixed (in case one
 591                                 or both jobs are not a required part
 592                                 of the transaction). In the latter
 593                                 case, the job that is not the required
 594                                 will be removed, or in case both are
 595                                 not required, the unit that conflicts
 596                                 will be started and the unit that is
 597                                 conflicted is
 598                                 stopped.</para></listitem>
 599                         </varlistentry>
 600
 601                         <varlistentry>
 602                                 <term><varname>Before=</varname></term>
 603                                 <term><varname>After=</varname></term>
 604
 605                                 <listitem><para>A space-separated list
 606                                 of unit names. Configures ordering
 607                                 dependencies between units. If a unit
 608                                 <filename>foo.service</filename>
 609                                 contains a setting
 610                                 <option>Before=bar.service</option>
 611                                 and both units are being started,
 612                                 <filename>bar.service</filename>'s
 613                                 start-up is delayed until
 614                                 <filename>foo.service</filename> is
 615                                 started up. Note that this setting is
 616                                 independent of and orthogonal to the
 617                                 requirement dependencies as configured
 618                                 by <varname>Requires=</varname>. It is
 619                                 a common pattern to include a unit
 620                                 name in both the
 621                                 <varname>After=</varname> and
 622                                 <varname>Requires=</varname> option, in
 623                                 which case the unit listed will be
 624                                 started before the unit that is
 625                                 configured with these options. This
 626                                 option may be specified more than
 627                                 once, in which case ordering
 628                                 dependencies for all listed names are
 629                                 created. <varname>After=</varname> is
 630                                 the inverse of
 631                                 <varname>Before=</varname>, i.e. while
 632                                 <varname>After=</varname> ensures that
 633                                 the configured unit is started after
 634                                 the listed unit finished starting up,
 635                                 <varname>Before=</varname> ensures the
 636                                 opposite, i.e.  that the configured
 637                                 unit is fully started up before the
 638                                 listed unit is started. Note that when
 639                                 two units with an ordering dependency
 640                                 between them are shut down, the
 641                                 inverse of the start-up order is
 642                                 applied. i.e. if a unit is configured
 643                                 with <varname>After=</varname> on
 644                                 another unit, the former is stopped
 645                                 before the latter if both are shut
 646                                 down. If one unit with an ordering
 647                                 dependency on another unit is shut
 648                                 down while the latter is started up,
 649                                 the shut down is ordered before the
 650                                 start-up regardless of whether the
 651                                 ordering dependency is actually of
 652                                 type <varname>After=</varname> or
 653                                 <varname>Before=</varname>. If two
 654                                 units have no ordering dependencies
 655                                 between them, they are shut down or
 656                                 started up simultaneously, and no
 657                                 ordering takes
 658                                 place. </para></listitem>
 659                         </varlistentry>
 660
 661                         <varlistentry>
 662                                 <term><varname>OnFailure=</varname></term>
 663
 664                                 <listitem><para>A space-separated list
 665                                 of one or more units that are
 666                                 activated when this unit enters the
 667                                 <literal>failed</literal>
 668                                 state.</para></listitem>
 669                         </varlistentry>
 670
 671                         <varlistentry>
 672                                 <term><varname>PropagatesReloadTo=</varname></term>
 673                                 <term><varname>ReloadPropagatedFrom=</varname></term>
 674
 675                                 <listitem><para>A space-separated list
 676                                 of one or more units where reload
 677                                 requests on this unit will be
 678                                 propagated to, or reload requests on
 679                                 the other unit will be propagated to
 680                                 this unit, respectively. Issuing a
 681                                 reload request on a unit will
 682                                 automatically also enqueue a reload
 683                                 request on all units that the reload
 684                                 request shall be propagated to via
 685                                 these two settings.</para></listitem>
 686                         </varlistentry>
 687
 688                         <varlistentry>
 689                                 <term><varname>JoinsNamespaceOf=</varname></term>
 690
 691                                 <listitem><para>For units that start
 692                                 processes (such as service units),
 693                                 lists one or more other units whose
 694                                 network and/or temporary file
 695                                 namespace to join. This only applies
 696                                 to unit types which support the
 697                                 <varname>PrivateNetwork=</varname> and
 698                                 <varname>PrivateTmp=</varname>
 699                                 directives (see
 700                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 701                                 for details). If a unit that has this
 702                                 setting set is started, its processes
 703                                 will see the same
 704                                 <filename>/tmp</filename>,
 705                                 <filename>/tmp/var</filename> and
 706                                 network namespace as one listed unit
 707                                 that is started. If multiple listed
 708                                 units are already started, it is not
 709                                 defined which namespace is
 710                                 joined. Note that this setting only
 711                                 has an effect if
 712                                 <varname>PrivateNetwork=</varname>
 713                                 and/or <varname>PrivateTmp=</varname>
 714                                 is enabled for both the unit that
 715                                 joins the namespace and the unit whose
 716                                 namespace is joined.</para></listitem>
 717                         </varlistentry>
 718
 719                         <varlistentry>
 720                                 <term><varname>RequiresMountsFor=</varname></term>
 721
 722                                 <listitem><para>Takes a
 723                                 space-separated list of absolute
 724                                 paths. Automatically adds dependencies
 725                                 of type <varname>Requires=</varname>
 726                                 and <varname>After=</varname> for all
 727                                 mount units required to access the
 728                                 specified path.</para>
 729
 730                                 <para>Mount points marked with
 731                                 <option>noauto</option> are not
 732                                 mounted automatically and will be
 733                                 ignored for the purposes of this
 734                                 option. If such a mount should be a
 735                                 requirement for this unit,
 736                                 direct dependencies on the mount
 737                                 units may be added
 738                                 (<varname>Requires=</varname> and
 739                                 <varname>After=</varname> or
 740                                 some other combination).
 741                                 </para></listitem>
 742                         </varlistentry>
 743
 744                         <varlistentry>
 745                                 <term><varname>OnFailureJobMode=</varname></term>
 746
 747                                 <listitem><para>Takes a value of
 748                                 <literal>fail</literal>,
 749                                 <literal>replace</literal>,
 750                                 <literal>replace-irreversibly</literal>,
 751                                 <literal>isolate</literal>,
 752                                 <literal>flush</literal>,
 753                                 <literal>ignore-dependencies</literal>
 754                                 or
 755                                 <literal>ignore-requirements</literal>. Defaults
 756                                 to
 757                                 <literal>replace</literal>. Specifies
 758                                 how the units listed in
 759                                 <varname>OnFailure=</varname> will be
 760                                 enqueued. See
 761                                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 762                                 <option>--job-mode=</option> option
 763                                 for details on the possible values. If
 764                                 this is set to
 765                                 <literal>isolate</literal>, only a
 766                                 single unit may be listed in
 767                                 <varname>OnFailure=</varname>..</para></listitem>
 768                         </varlistentry>
 769
 770                         <varlistentry>
 771                                 <term><varname>IgnoreOnIsolate=</varname></term>
 772
 773                                 <listitem><para>Takes a boolean
 774                                 argument. If <option>true</option>,
 775                                 this unit will not be stopped when
 776                                 isolating another unit. Defaults to
 777                                 <option>false</option>.</para></listitem>
 778                         </varlistentry>
 779
 780                         <varlistentry>
 781                                 <term><varname>IgnoreOnSnapshot=</varname></term>
 782
 783                                 <listitem><para>Takes a boolean
 784                                 argument. If <option>true</option>,
 785                                 this unit will not be included in
 786                                 snapshots. Defaults to
 787                                 <option>true</option> for device and
 788                                 snapshot units, <option>false</option>
 789                                 for the others.</para></listitem>
 790                         </varlistentry>
 791
 792                         <varlistentry>
 793                                 <term><varname>StopWhenUnneeded=</varname></term>
 794
 795                                 <listitem><para>Takes a boolean
 796                                 argument. If <option>true</option>,
 797                                 this unit will be stopped when it is
 798                                 no longer used. Note that in order to
 799                                 minimize the work to be executed,
 800                                 systemd will not stop units by default
 801                                 unless they are conflicting with other
 802                                 units, or the user explicitly
 803                                 requested their shut down. If this
 804                                 option is set, a unit will be
 805                                 automatically cleaned up if no other
 806                                 active unit requires it. Defaults to
 807                                 <option>false</option>.</para></listitem>
 808                         </varlistentry>
 809
 810                         <varlistentry>
 811                                 <term><varname>RefuseManualStart=</varname></term>
 812                                 <term><varname>RefuseManualStop=</varname></term>
 813
 814                                 <listitem><para>Takes a boolean
 815                                 argument. If <option>true</option>,
 816                                 this unit can only be activated
 817                                 or deactivated indirectly. In
 818                                 this case, explicit start-up
 819                                 or termination requested by the
 820                                 user is denied, however if it is
 821                                 started or stopped as a
 822                                 dependency of another unit, start-up
 823                                 or termination will succeed. This
 824                                 is mostly a safety feature to ensure
 825                                 that the user does not accidentally
 826                                 activate units that are not intended
 827                                 to be activated explicitly, and not
 828                                 accidentally deactivate units that are
 829                                 not intended to be deactivated.
 830                                 These options default to
 831                                 <option>false</option>.</para></listitem>
 832                         </varlistentry>
 833
 834                         <varlistentry>
 835                                 <term><varname>AllowIsolate=</varname></term>
 836
 837                                 <listitem><para>Takes a boolean
 838                                 argument. If <option>true</option>,
 839                                 this unit may be used with the
 840                                 <command>systemctl isolate</command>
 841                                 command. Otherwise, this will be
 842                                 refused. It probably is a good idea to
 843                                 leave this disabled except for target
 844                                 units that shall be used similar to
 845                                 runlevels in SysV init systems, just
 846                                 as a precaution to avoid unusable
 847                                 system states. This option defaults to
 848                                 <option>false</option>.</para></listitem>
 849                         </varlistentry>
 850
 851                         <varlistentry>
 852                                 <term><varname>DefaultDependencies=</varname></term>
 853
 854                                 <listitem><para>Takes a boolean
 855                                 argument. If <option>true</option>,
 856                                 (the default), a few default
 857                                 dependencies will implicitly be
 858                                 created for the unit. The actual
 859                                 dependencies created depend on the
 860                                 unit type. For example, for service
 861                                 units, these dependencies ensure that
 862                                 the service is started only after
 863                                 basic system initialization is
 864                                 completed and is properly terminated on
 865                                 system shutdown. See the respective
 866                                 man pages for details. Generally, only
 867                                 services involved with early boot or
 868                                 late shutdown should set this option
 869                                 to <option>false</option>. It is
 870                                 highly recommended to leave this
 871                                 option enabled for the majority of
 872                                 common units. If set to
 873                                 <option>false</option>, this option
 874                                 does not disable all implicit
 875                                 dependencies, just non-essential
 876                                 ones.</para></listitem>
 877                         </varlistentry>
 878
 879                         <varlistentry>
 880                                 <term><varname>JobTimeoutSec=</varname></term>
 881
 882                                 <listitem><para>When clients are
 883                                 waiting for a job of this unit to
 884                                 complete, time out after the specified
 885                                 time. If this time limit is reached,
 886                                 the job will be cancelled, the unit
 887                                 however will not change state or even
 888                                 enter the <literal>failed</literal>
 889                                 mode. This value defaults to 0 (job
 890                                 timeouts disabled), except for device
 891                                 units. NB: this timeout is independent
 892                                 from any unit-specific timeout (for
 893                                 example, the timeout set with
 894                                 <varname>Timeout=</varname> in service
 895                                 units) as the job timeout has no
 896                                 effect on the unit itself, only on the
 897                                 job that might be pending for it. Or
 898                                 in other words: unit-specific timeouts
 899                                 are useful to abort unit state
 900                                 changes, and revert them. The job
 901                                 timeout set with this option however
 902                                 is useful to abort only the job
 903                                 waiting for the unit state to
 904                                 change.</para></listitem>
 905                         </varlistentry>
 906
 907                         <varlistentry>
 908                                 <term><varname>ConditionArchitecture=</varname></term>
 909                                 <term><varname>ConditionVirtualization=</varname></term>
 910                                 <term><varname>ConditionHost=</varname></term>
 911                                 <term><varname>ConditionKernelCommandLine=</varname></term>
 912                                 <term><varname>ConditionSecurity=</varname></term>
 913                                 <term><varname>ConditionCapability=</varname></term>
 914                                 <term><varname>ConditionACPower=</varname></term>
 915                                 <term><varname>ConditionNeedsUpdate=</varname></term>
 916                                 <term><varname>ConditionFirstBoot=</varname></term>
 917                                 <term><varname>ConditionPathExists=</varname></term>
 918                                 <term><varname>ConditionPathExistsGlob=</varname></term>
 919                                 <term><varname>ConditionPathIsDirectory=</varname></term>
 920                                 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
 921                                 <term><varname>ConditionPathIsMountPoint=</varname></term>
 922                                 <term><varname>ConditionPathIsReadWrite=</varname></term>
 923                                 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
 924                                 <term><varname>ConditionFileNotEmpty=</varname></term>
 925                                 <term><varname>ConditionFileIsExecutable=</varname></term>
 926                                 <term><varname>ConditionNull=</varname></term>
 927
 928                                 <listitem><para>Before starting a unit
 929                                 verify that the specified condition is
 930                                 true. If it is not true, the starting
 931                                 of the unit will be skipped, however
 932                                 all ordering dependencies of it are
 933                                 still respected. A failing condition
 934                                 will not result in the unit being
 935                                 moved into a failure state. The
 936                                 condition is checked at the time the
 937                                 queued start job is to be
 938                                 executed.</para>
 939
 940                                 <para><varname>ConditionArchitecture=</varname>
 941                                 may be used to check whether the
 942                                 system is running on a specific
 943                                 architecture. Takes one of
 944                                 <varname>x86</varname>,
 945                                 <varname>x86-64</varname>,
 946                                 <varname>ppc</varname>,
 947                                 <varname>ppc-le</varname>,
 948                                 <varname>ppc64</varname>,
 949                                 <varname>ppc64-le</varname>,
 950                                 <varname>ia64</varname>,
 951                                 <varname>parisc</varname>,
 952                                 <varname>parisc64</varname>,
 953                                 <varname>s390</varname>,
 954                                 <varname>s390x</varname>,
 955                                 <varname>sparc</varname>,
 956                                 <varname>sparc64</varname>,
 957                                 <varname>mips</varname>,
 958                                 <varname>mips-le</varname>,
 959                                 <varname>mips64</varname>,
 960                                 <varname>mips64-le</varname>,
 961                                 <varname>alpha</varname>,
 962                                 <varname>arm</varname>,
 963                                 <varname>arm-be</varname>,
 964                                 <varname>arm64</varname>,
 965                                 <varname>arm64-be</varname>,
 966                                 <varname>sh</varname>,
 967                                 <varname>sh64</varname>,
 968                                 <varname>m86k</varname>,
 969                                 <varname>tilegx</varname>,
 970                                 <varname>cris</varname> to test
 971                                 against a specific architecture. The
 972                                 architecture is determined from the
 973                                 information returned by
 974                                 <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 975                                 and is thus subject to
 976                                 <citerefentry><refentrytitle>personality</refentrytitle><manvolnum>2</manvolnum></citerefentry>. Note
 977                                 that a <varname>Personality=</varname>
 978                                 setting in the same unit file has no
 979                                 effect on this condition. A special
 980                                 architecture name
 981                                 <varname>native</varname> is mapped to
 982                                 the architecture the system manager
 983                                 itself is compiled for. The test may
 984                                 be negated by prepending an
 985                                 exclamation mark.</para>
 986
 987                                 <para><varname>ConditionVirtualization=</varname>
 988                                 may be used to check whether the
 989                                 system is executed in a virtualized
 990                                 environment and optionally test
 991                                 whether it is a specific
 992                                 implementation. Takes either boolean
 993                                 value to check if being executed in
 994                                 any virtualized environment, or one of
 995                                 <varname>vm</varname> and
 996                                 <varname>container</varname> to test
 997                                 against a generic type of
 998                                 virtualization solution, or one of
 999                                 <varname>qemu</varname>,
1000                                 <varname>kvm</varname>,
1001                                 <varname>zvm</varname>,
1002                                 <varname>vmware</varname>,
1003                                 <varname>microsoft</varname>,
1004                                 <varname>oracle</varname>,
1005                                 <varname>xen</varname>,
1006                                 <varname>bochs</varname>,
1007                                 <varname>uml</varname>,
1008                                 <varname>openvz</varname>,
1009                                 <varname>lxc</varname>,
1010                                 <varname>lxc-libvirt</varname>,
1011                                 <varname>systemd-nspawn</varname> to
1012                                 test against a specific
1013                                 implementation. If multiple
1014                                 virtualization technologies are nested,
1015                                 only the innermost is considered. The
1016                                 test may be negated by prepending an
1017                                 exclamation mark.</para>
1018
1019                                 <para><varname>ConditionHost=</varname>
1020                                 may be used to match against the
1021                                 hostname or machine ID of the
1022                                 host. This either takes a hostname
1023                                 string (optionally with shell style
1024                                 globs) which is tested against the
1025                                 locally set hostname as returned by
1026                                 <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
1027                                 or a machine ID formatted as string
1028                                 (see
1029                                 <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
1030                                 The test may be negated by prepending
1031                                 an exclamation mark.</para>
1032
1033                                 <para><varname>ConditionKernelCommandLine=</varname>
1034                                 may be used to check whether a
1035                                 specific kernel command line option is
1036                                 set (or if prefixed with the
1037                                 exclamation mark unset). The argument
1038                                 must either be a single word, or an
1039                                 assignment (i.e. two words, separated
1040                                 <literal>=</literal>). In the former
1041                                 case the kernel command line is
1042                                 searched for the word appearing as is,
1043                                 or as left hand side of an
1044                                 assignment. In the latter case, the
1045                                 exact assignment is looked for with
1046                                 right and left hand side
1047                                 matching.</para>
1048
1049                                 <para><varname>ConditionSecurity=</varname>
1050                                 may be used to check whether the given
1051                                 security module is enabled on the
1052                                 system. Currently the recognized values
1053                                 values are <varname>selinux</varname>,
1054                                 <varname>apparmor</varname>,
1055                                 <varname>ima</varname> and
1056                                 <varname>smack</varname>.
1057                                 The test may be negated by prepending
1058                                 an exclamation
1059                                 mark.</para>
1060
1061                                 <para><varname>ConditionCapability=</varname>
1062                                 may be used to check whether the given
1063                                 capability exists in the capability
1064                                 bounding set of the service manager
1065                                 (i.e. this does not check whether
1066                                 capability is actually available in
1067                                 the permitted or effective sets, see
1068                                 <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1069                                 for details). Pass a capability name
1070                                 such as <literal>CAP_MKNOD</literal>,
1071                                 possibly prefixed with an exclamation
1072                                 mark to negate the check.</para>
1073
1074                                 <para><varname>ConditionACPower=</varname>
1075                                 may be used to check whether the
1076                                 system has AC power, or is exclusively
1077                                 battery powered at the time of
1078                                 activation of the unit. This takes a
1079                                 boolean argument. If set to
1080                                 <varname>true</varname>, the condition
1081                                 will hold only if at least one AC
1082                                 connector of the system is connected
1083                                 to a power source, or if no AC
1084                                 connectors are known. Conversely, if
1085                                 set to <varname>false</varname>, the
1086                                 condition will hold only if there is
1087                                 at least one AC connector known and
1088                                 all AC connectors are disconnected
1089                                 from a power source.</para>
1090
1091                                 <para><varname>ConditionNeedsUpdate=</varname>
1092                                 takes one of <filename>/var</filename>
1093                                 or <filename>/etc</filename> as
1094                                 argument, possibly prefixed with a
1095                                 <literal>!</literal> (for inverting
1096                                 the condition). This condition may be
1097                                 used to conditionalize units on
1098                                 whether the specified directory
1099                                 requires an update because
1100                                 <filename>/usr</filename>'s
1101                                 modification time is newer than the
1102                                 stamp file
1103                                 <filename>.updated</filename> in the
1104                                 specified directory. This is useful to
1105                                 implement offline updates of the
1106                                 vendor operating system resources in
1107                                 <filename>/usr</filename> that require
1108                                 updating of <filename>/etc</filename>
1109                                 or <filename>/var</filename> on the
1110                                 next following boot. Units making use
1111                                 of this condition should order
1112                                 themselves before
1113                                 <citerefentry><refentrytitle>systemd-update-done.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1114                                 to make sure they run before the stamp
1115                                 files's modification time gets reset
1116                                 indicating a completed update.</para>
1117
1118                                 <para><varname>ConditionFirstBoot=</varname>
1119                                 takes a boolean argument. This
1120                                 condition may be used to
1121                                 conditionalize units on whether the
1122                                 system is booting up with an
1123                                 unpopulated <filename>/etc</filename>
1124                                 directory. This may be used to
1125                                 populate <filename>/etc</filename> on
1126                                 the first boot after factory reset, or
1127                                 when a new system instances boots up
1128                                 for the first time.</para>
1129
1130                                 <para>With
1131                                 <varname>ConditionPathExists=</varname>
1132                                 a file existence condition is
1133                                 checked before a unit is started. If
1134                                 the specified absolute path name does
1135                                 not exist, the condition will
1136                                 fail. If the absolute path name passed
1137                                 to
1138                                 <varname>ConditionPathExists=</varname>
1139                                 is prefixed with an exclamation mark
1140                                 (<literal>!</literal>), the test is negated, and the unit
1141                                 is only started if the path does not
1142                                 exist.</para>
1143
1144                                 <para><varname>ConditionPathExistsGlob=</varname>
1145                                 is similar to
1146                                 <varname>ConditionPathExists=</varname>,
1147                                 but checks for the existence of at
1148                                 least one file or directory matching
1149                                 the specified globbing pattern.</para>
1150
1151                                 <para><varname>ConditionPathIsDirectory=</varname>
1152                                 is similar to
1153                                 <varname>ConditionPathExists=</varname>
1154                                 but verifies whether a certain path
1155                                 exists and is a
1156                                 directory.</para>
1157
1158                                 <para><varname>ConditionPathIsSymbolicLink=</varname>
1159                                 is similar to
1160                                 <varname>ConditionPathExists=</varname>
1161                                 but verifies whether a certain path
1162                                 exists and is a symbolic
1163                                 link.</para>
1164
1165                                 <para><varname>ConditionPathIsMountPoint=</varname>
1166                                 is similar to
1167                                 <varname>ConditionPathExists=</varname>
1168                                 but verifies whether a certain path
1169                                 exists and is a mount
1170                                 point.</para>
1171
1172                                 <para><varname>ConditionPathIsReadWrite=</varname>
1173                                 is similar to
1174                                 <varname>ConditionPathExists=</varname>
1175                                 but verifies whether the underlying
1176                                 file system is readable and writable
1177                                 (i.e. not mounted
1178                                 read-only).</para>
1179
1180                                 <para><varname>ConditionDirectoryNotEmpty=</varname>
1181                                 is similar to
1182                                 <varname>ConditionPathExists=</varname>
1183                                 but verifies whether a certain path
1184                                 exists and is a non-empty
1185                                 directory.</para>
1186
1187                                 <para><varname>ConditionFileNotEmpty=</varname>
1188                                 is similar to
1189                                 <varname>ConditionPathExists=</varname>
1190                                 but verifies whether a certain path
1191                                 exists and refers to a regular file
1192                                 with a non-zero size.</para>
1193
1194                                 <para><varname>ConditionFileIsExecutable=</varname>
1195                                 is similar to
1196                                 <varname>ConditionPathExists=</varname>
1197                                 but verifies whether a certain path
1198                                 exists, is a regular file and marked
1199                                 executable.</para>
1200
1201                                 <para>Finally,
1202                                 <varname>ConditionNull=</varname> may
1203                                 be used to add a constant condition
1204                                 check value to the unit. It takes a
1205                                 boolean argument. If set to
1206                                 <varname>false</varname>, the condition
1207                                 will always fail, otherwise
1208                                 succeed.</para>
1209
1210                                 <para>If multiple conditions are
1211                                 specified, the unit will be executed if
1212                                 all of them apply (i.e. a logical AND
1213                                 is applied). Condition checks can be
1214                                 prefixed with a pipe symbol (|) in
1215                                 which case a condition becomes a
1216                                 triggering condition. If at least one
1217                                 triggering condition is defined for a
1218                                 unit, then the unit will be executed if
1219                                 at least one of the triggering
1220                                 conditions apply and all of the
1221                                 non-triggering conditions. If you
1222                                 prefix an argument with the pipe
1223                                 symbol and an exclamation mark, the
1224                                 pipe symbol must be passed first, the
1225                                 exclamation second. Except for
1226                                 <varname>ConditionPathIsSymbolicLink=</varname>,
1227                                 all path checks follow symlinks. If
1228                                 any of these options is assigned the
1229                                 empty string, the list of conditions is
1230                                 reset completely, all previous
1231                                 condition settings (of any kind) will
1232                                 have no effect.</para></listitem>
1233                         </varlistentry>
1234
1235                         <varlistentry>
1236                                 <term><varname>SourcePath=</varname></term>
1237                                 <listitem><para>A path to a
1238                                 configuration file this unit has been
1239                                 generated from. This is primarily
1240                                 useful for implementation of generator
1241                                 tools that convert configuration from
1242                                 an external configuration file format
1243                                 into native unit files. This
1244                                 functionality should not be used in
1245                                 normal units.</para></listitem>
1246                         </varlistentry>
1247                 </variablelist>
1248
1249         </refsect1>
1250
1251         <refsect1>
1252                 <title>[Install] Section Options</title>
1253
1254                 <para>Unit file may include a [Install] section, which
1255                 carries installation information for the unit. This
1256                 section is not interpreted by
1257                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1258                 during runtime. It is used exclusively by the
1259                 <command>enable</command> and
1260                 <command>disable</command> commands of the
1261                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1262                 tool during installation of a unit:</para>
1263
1264                 <variablelist class='unit-directives'>
1265                         <varlistentry>
1266                                 <term><varname>Alias=</varname></term>
1267
1268                                 <listitem><para>A space-seperated list
1269                                 of additional names this unit shall be
1270                                 installed under. The names listed here
1271                                 must have the same suffix (i.e. type)
1272                                 as the unit file name. This option may
1273                                 be specified more than once, in which
1274                                 case all listed names are used. At
1275                                 installation time, <command>systemctl
1276                                 enable</command> will create symlinks
1277                                 from these names to the unit
1278                                 filename.</para></listitem>
1279                         </varlistentry>
1280
1281                         <varlistentry>
1282                                 <term><varname>WantedBy=</varname></term>
1283                                 <term><varname>RequiredBy=</varname></term>
1284
1285                                 <listitem><para>This option may be
1286                                 used more than once, or a
1287                                 space-separated list of unit names may
1288                                 be given. A symbolic link is created
1289                                 in the <filename>.wants/</filename> or
1290                                 <filename>.requires/</filename>
1291                                 directory of each of the listed units
1292                                 when this unit is installed by
1293                                 <command>systemctl enable</command>.
1294                                 This has the effect that a dependency
1295                                 of type <varname>Wants=</varname> or
1296                                 <varname>Requires=</varname> is added
1297                                 from the listed unit to the current
1298                                 unit. The primary result is that the
1299                                 current unit will be started when the
1300                                 listed unit is started. See the
1301                                 description of
1302                                 <varname>Wants=</varname> and
1303                                 <varname>Requires=</varname> in the
1304                                 [Unit] section for details.</para>
1305
1306                                 <para><command>WantedBy=foo.service</command>
1307                                 in a service
1308                                 <filename>bar.service</filename> is
1309                                 mostly equivalent to
1310                                 <command>Alias=foo.service.wants/bar.service</command>
1311                                 in the same file. In case of template
1312                                 units, <command>systemctl enable</command>
1313                                 must be called with an instance name, and
1314                                 this instance will be added to the
1315                                 <filename>.wants/</filename> or
1316                                 <filename>.requires/</filename> list
1317                                 of the listed unit.
1318                                 E.g. <command>WantedBy=getty.target</command>
1319                                 in a service
1320                                 <filename>getty@.service</filename>
1321                                 will result in <command>systemctl
1322                                 enable getty@tty2.service</command>
1323                                 creating a
1324                                 <filename>getty.target.wants/getty@tty2.service</filename>
1325                                 link to <filename>getty@.service</filename>.
1326                                 </para></listitem>
1327                         </varlistentry>
1328
1329                         <varlistentry>
1330                                 <term><varname>Also=</varname></term>
1331
1332                                 <listitem><para>Additional units to
1333                                 install/deinstall when this unit is
1334                                 installed/deinstalled. If the user
1335                                 requests installation/deinstallation
1336                                 of a unit with this option configured,
1337                                 <command>systemctl enable</command>
1338                                 and <command>systemctl
1339                                 disable</command> will automatically
1340                                 install/uninstall units listed in this option as
1341                                 well.</para>
1342
1343                                 <para>This option may be used more
1344                                 than once, or a space-separated list
1345                                 of unit names may be
1346                                 given.</para></listitem>
1347                         </varlistentry>
1348
1349                         <varlistentry>
1350                                 <term><varname>DefaultInstance=</varname></term>
1351
1352                                 <listitem><para>In template unit files,
1353                                 this specifies for which instance the
1354                                 unit shall be enabled if the template
1355                                 is enabled without any explicitly set
1356                                 instance. This option has no effect in
1357                                 non-template unit files. The specified
1358                                 string must be usable as instance
1359                                 identifier.</para></listitem>
1360                         </varlistentry>
1361                 </variablelist>
1362
1363                 <para>The following specifiers are interpreted in the
1364                 Install section: %n, %N, %p, %i, %U, %u, %m, %H, %b, %v.
1365                 For their meaning see the next section.
1366                 </para>
1367         </refsect1>
1368
1369         <refsect1>
1370                 <title>Specifiers</title>
1371
1372                 <para>Many settings resolve specifiers which may be
1373                 used to write generic unit files referring to runtime
1374                 or unit parameters that are replaced when the unit
1375                 files are loaded. The following specifiers are
1376                 understood:</para>
1377
1378                 <table>
1379                   <title>Specifiers available in unit files</title>
1380                   <tgroup cols='3' align='left' colsep='1' rowsep='1'>
1381                     <colspec colname="spec" />
1382                     <colspec colname="mean" />
1383                     <colspec colname="detail" />
1384                     <thead>
1385                       <row>
1386                         <entry>Specifier</entry>
1387                         <entry>Meaning</entry>
1388                         <entry>Details</entry>
1389                       </row>
1390                     </thead>
1391                     <tbody>
1392                       <row>
1393                         <entry><literal>%n</literal></entry>
1394                         <entry>Full unit name</entry>
1395                         <entry></entry>
1396                       </row>
1397                       <row>
1398                         <entry><literal>%N</literal></entry>
1399                         <entry>Unescaped full unit name</entry>
1400                         <entry>Same as <literal>%n</literal>, but with escaping undone</entry>
1401                       </row>
1402                       <row>
1403                         <entry><literal>%p</literal></entry>
1404                         <entry>Prefix name</entry>
1405                         <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>
1406                       </row>
1407                       <row>
1408                         <entry><literal>%P</literal></entry>
1409                         <entry>Unescaped prefix name</entry>
1410                         <entry>Same as <literal>%p</literal>, but with escaping undone</entry>
1411                       </row>
1412                       <row>
1413                         <entry><literal>%i</literal></entry>
1414                         <entry>Instance name</entry>
1415                         <entry>For instantiated units: this is the string between the <literal>@</literal> character and the suffix of the unit name.</entry>
1416                       </row>
1417                       <row>
1418                         <entry><literal>%I</literal></entry>
1419                         <entry>Unescaped instance name</entry>
1420                         <entry>Same as <literal>%i</literal>, but with escaping undone</entry>
1421                       </row>
1422                       <row>
1423                         <entry><literal>%f</literal></entry>
1424                         <entry>Unescaped filename</entry>
1425                         <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>
1426                       </row>
1427                       <row>
1428                         <entry><literal>%c</literal></entry>
1429                         <entry>Control group path of the unit</entry>
1430                         <entry>This path does not include the <filename>/sys/fs/cgroup/systemd/</filename> prefix.</entry>
1431                       </row>
1432                       <row>
1433                         <entry><literal>%r</literal></entry>
1434                         <entry>Control group path of the slice the unit is placed in</entry>
1435                         <entry>This usually maps to the parent cgroup path of <literal>%c</literal>.</entry>
1436                       </row>
1437                       <row>
1438                         <entry><literal>%R</literal></entry>
1439                         <entry>Root control group path below which slices and units are placed</entry>
1440                         <entry>For system instances, this resolves to <filename>/</filename>, except in containers, where this maps to the container's root control group path.</entry>
1441                       </row>
1442                       <row>
1443                         <entry><literal>%t</literal></entry>
1444                         <entry>Runtime directory</entry>
1445                         <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>
1446                       </row>
1447                       <row>
1448                         <entry><literal>%u</literal></entry>
1449                         <entry>User name</entry>
1450                         <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1451                       </row>
1452                       <row>
1453                         <entry><literal>%U</literal></entry>
1454                         <entry>User UID</entry>
1455                         <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>
1456                       </row>
1457                       <row>
1458                         <entry><literal>%h</literal></entry>
1459                         <entry>User home directory</entry>
1460                         <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>
1461                       </row>
1462                       <row>
1463                         <entry><literal>%s</literal></entry>
1464                         <entry>User shell</entry>
1465                         <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>
1466                       </row>
1467                       <row>
1468                         <entry><literal>%m</literal></entry>
1469                         <entry>Machine ID</entry>
1470                         <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>
1471                       </row>
1472                       <row>
1473                         <entry><literal>%b</literal></entry>
1474                         <entry>Boot ID</entry>
1475                         <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
1476                       </row>
1477                       <row>
1478                         <entry><literal>%H</literal></entry>
1479                         <entry>Host name</entry>
1480                         <entry>The hostname of the running system at the point in time the unit configuation is loaded.</entry>
1481                       </row>
1482                       <row>
1483                         <entry><literal>%v</literal></entry>
1484                         <entry>Kernel release</entry>
1485                         <entry>Identical to <command>uname -r</command> output</entry>
1486                       </row>
1487                       <row>
1488                         <entry><literal>%%</literal></entry>
1489                         <entry>Single percent sign</entry>
1490                         <entry>Use <literal>%%</literal> in place of <literal>%</literal> to specify a single percent sign.</entry>
1491                       </row>
1492                     </tbody>
1493                   </tgroup>
1494                 </table>
1495         </refsect1>
1496
1497         <refsect1>
1498                 <title>See Also</title>
1499                 <para>
1500                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1501                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1502                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1503                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1504                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1505                         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1506                         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1507                         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1508                         <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1509                         <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1510                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1511                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1512                         <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1513                         <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1514                         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1515                         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1516                         <citerefentry><refentrytitle>systemd-verify</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1517                         <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1518                         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1519                         <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1520                 </para>
1521         </refsect1>
1522
1523 </refentry>