man/systemd.unit.xml

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   3         "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" [
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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>$XDG_RUNTIME_DIR/systemd/user/*</filename>
  77 <filename>/run/systemd/user/*</filename>
  78 <filename>$XDG_DATA_HOME/systemd/user/*</filename>
  79 <filename>$HOME/.local/share/systemd/user/*</filename>
  80 <filename>/usr/lib/systemd/user/*</filename>
  81 <filename>...</filename>
  82                 </literallayout></para>
  83         </refsynopsisdiv>
  84
  85         <refsect1>
  86                 <title>Description</title>
  87
  88                 <para>A unit configuration file encodes information
  89                 about a service, a socket, a device, a mount point, an
  90                 automount point, a swap file or partition, a start-up
  91                 target, a watched file system path, a timer controlled
  92                 and supervised by
  93                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
  94                 a temporary system state snapshot, a resource
  95                 management slice or a group of externally created
  96                 processes. The syntax is inspired by <ulink
  97                 url="http://standards.freedesktop.org/desktop-entry-spec/latest/">XDG
  98                 Desktop Entry Specification</ulink>
  99                 <filename>.desktop</filename> files, which are in turn
 100                 inspired by Microsoft Windows
 101                 <filename>.ini</filename> files.</para>
 102
 103                 <para>This man page lists the common configuration
 104                 options of all the unit types. These options need to
 105                 be configured in the [Unit] or [Install]
 106                 sections of the unit files.</para>
 107
 108                 <para>In addition to the generic [Unit] and [Install]
 109                 sections described here, each unit may have a
 110                 type-specific section, e.g. [Service] for a service
 111                 unit. See the respective man pages for more
 112                 information:
 113                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 114                 <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 115                 <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 116                 <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 117                 <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 118                 <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 119                 <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 120                 <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 121                 <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
 122                 <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 123                 <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 124                 <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
 125                 </para>
 126
 127                 <para>Various settings are allowed to be specified
 128                 more than once, in which case the interpretation
 129                 depends on the setting. Often, multiple settings form
 130                 a list, and setting to an empty value "resets", which
 131                 means that previous assignments are ignored. When this
 132                 is allowed, it is mentioned in the description of the
 133                 setting. Note that using multiple assignments to the
 134                 same value makes the unit file incompatible with
 135                 parsers for the XDG <filename>.desktop</filename> file
 136                 format.</para>
 137
 138                 <para>Unit files are loaded from a set of paths
 139                 determined during compilation, described in the next section.
 140                 </para>
 141
 142                 <para>Unit files may contain additional options on top
 143                 of those listed here. If systemd encounters an unknown
 144                 option, it will write a warning log message but
 145                 continue loading the unit. If an option or section name
 146                 is prefixed with <option>X-</option>, it is ignored
 147                 completely by systemd. Options within an ignored
 148                 section do not need the prefix. Applications may use
 149                 this to include additional information in the unit
 150                 files.</para>
 151
 152                 <para>Boolean arguments used in unit files can be
 153                 written in various formats. For positive settings the
 154                 strings <option>1</option>, <option>yes</option>,
 155                 <option>true</option> and <option>on</option> are
 156                 equivalent. For negative settings, the strings
 157                 <option>0</option>, <option>no</option>,
 158                 <option>false</option> and <option>off</option> are
 159                 equivalent.</para>
 160
 161                 <para>Time span values encoded in unit files can be
 162                 written in various formats. A stand-alone number
 163                 specifies a time in seconds. If suffixed with a time
 164                 unit, the unit is honored. A concatenation of multiple
 165                 values with units is supported, in which case the
 166                 values are added up. Example: "50" refers to 50
 167                 seconds; "2min 200ms" refers to 2 minutes plus 200
 168                 milliseconds, i.e. 120200ms. The following time units
 169                 are understood: s, min, h, d, w, ms, us. For details
 170                 see
 171                 <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para>
 172
 173                 <para>Empty lines and lines starting with # or ; are
 174                 ignored. This may be used for commenting. Lines ending
 175                 in a backslash are concatenated with the following
 176                 line while reading and the backslash is replaced by a
 177                 space character. This may be used to wrap long lines.</para>
 178
 179                 <para>Along with a unit file
 180                 <filename>foo.service</filename>, the directory
 181                 <filename>foo.service.wants/</filename> may exist. All
 182                 unit files symlinked from such a directory are
 183                 implicitly added as dependencies of type
 184                 <varname>Wants=</varname> to the unit. This is useful
 185                 to hook units into the start-up of other units,
 186                 without having to modify their unit files. For details
 187                 about the semantics of <varname>Wants=</varname>, see
 188                 below. The preferred way to create symlinks in the
 189                 <filename>.wants/</filename> directory of a unit file
 190                 is with the <command>enable</command> command of the
 191                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
 192                 tool which reads information from the [Install]
 193                 section of unit files (see below). A similar
 194                 functionality exists for <varname>Requires=</varname>
 195                 type dependencies as well, the directory suffix is
 196                 <filename>.requires/</filename> in this case.</para>
 197
 198                 <para>Along with a unit file
 199                 <filename>foo.service</filename>, a directory
 200                 <filename>foo.service.d/</filename> may exist. All
 201                 files with the suffix <literal>.conf</literal> from
 202                 this directory will be parsed after the file itself is
 203                 parsed. This is useful to alter or add configuration
 204                 settings to a unit, without having to modify their
 205                 unit files. Make sure that the file that is included
 206                 has the appropriate section headers before any
 207                 directive. Note that for instanced units this logic
 208                 will first look for the instance
 209                 <literal>.d/</literal> subdirectory and read its
 210                 <literal>.conf</literal> files, followed by the
 211                 template <literal>.d/</literal> subdirectory and reads
 212                 its <literal>.conf</literal> files.</para>
 213
 214                 <!-- Note that we do not document .include here, as we
 215                      consider it mostly obsolete, and want people to
 216                      use .d/ drop-ins instead. -->
 217
 218                 <para>Note that while systemd offers a flexible
 219                 dependency system between units it is recommended to
 220                 use this functionality only sparingly and instead rely
 221                 on techniques such as bus-based or socket-based
 222                 activation which make dependencies implicit, resulting
 223                 in a both simpler and more flexible system.</para>
 224
 225                 <para>Some unit names reflect paths existing in the
 226                 file system namespace. Example: a device unit
 227                 <filename>dev-sda.device</filename> refers to a device
 228                 with the device node <filename noindex='true'>/dev/sda</filename> in
 229                 the file system namespace. If this applies, a special
 230                 way to escape the path name is used, so that the
 231                 result is usable as part of a filename. Basically,
 232                 given a path, "/" is replaced by "-", and all
 233                 unprintable characters and the "-" are replaced by
 234                 C-style "\x2d" escapes. The root directory "/" is
 235                 encoded as single dash, while otherwise the initial
 236                 and ending "/" is removed from all paths during
 237                 transformation. This escaping is reversible.</para>
 238
 239                 <para>Optionally, units may be instantiated from a
 240                 template file at runtime. This allows creation of
 241                 multiple units from a single configuration file. If
 242                 systemd looks for a unit configuration file, it will
 243                 first search for the literal unit name in the
 244                 file system. If that yields no success and the unit
 245                 name contains an <literal>@</literal> character, systemd will look for a
 246                 unit template that shares the same name but with the
 247                 instance string (i.e. the part between the <literal>@</literal> character
 248                 and the suffix) removed. Example: if a service
 249                 <filename>getty@tty3.service</filename> is requested
 250                 and no file by that name is found, systemd will look
 251                 for <filename>getty@.service</filename> and
 252                 instantiate a service from that configuration file if
 253                 it is found.</para>
 254
 255                 <para>To refer to the instance string from
 256                 within the configuration file you may use the special
 257                 <literal>%i</literal> specifier in many of the
 258                 configuration options. See below for details.</para>
 259
 260                 <para>If a unit file is empty (i.e. has the file size
 261                 0) or is symlinked to <filename>/dev/null</filename>,
 262                 its configuration will not be loaded and it appears
 263                 with a load state of <literal>masked</literal>, and
 264                 cannot be activated. Use this as an effective way to
 265                 fully disable a unit, making it impossible to start it
 266                 even manually.</para>
 267
 268                 <para>The unit file format is covered by the
 269                 <ulink
 270                 url="http://www.freedesktop.org/wiki/Software/systemd/InterfaceStabilityPromise">Interface
 271                 Stability Promise</ulink>.</para>
 272
 273         </refsect1>
 274
 275         <refsect1>
 276                 <title>Unit Load Path</title>
 277
 278                 <para>Unit files are loaded from a set of paths
 279                 determined during compilation, described in the two
 280                 tables below. Unit files found in directories listed
 281                 earlier override files with the same name in
 282                 directories lower in the list.</para>
 283
 284                 <para>When systemd is running in user mode
 285                 (<option>--user</option>) and the variable
 286                 <varname>$SYSTEMD_UNIT_PATH</varname> is set, this
 287                 contents of this variable overrides the unit load
 288                 path. If <varname>$SYSTEMD_UNIT_PATH</varname> ends
 289                 with an empty component (<literal>:</literal>), the
 290                 usual unit load path will be appended to the contents
 291                 of the variable.</para>
 292
 293                 <table>
 294                   <title>
 295                     Load path when running in system mode (<option>--system</option>).
 296                   </title>
 297
 298                   <tgroup cols='2'>
 299                     <colspec colname='path' />
 300                     <colspec colname='expl' />
 301                     <thead>
 302                       <row>
 303                         <entry>Path</entry>
 304                         <entry>Description</entry>
 305                       </row>
 306                     </thead>
 307                     <tbody>
 308                       <row>
 309                         <entry><filename>/etc/systemd/system</filename></entry>
 310                         <entry>Local configuration</entry>
 311                       </row>
 312                       <row>
 313                         <entry><filename>/run/systemd/system</filename></entry>
 314                         <entry>Runtime units</entry>
 315                       </row>
 316                       <row>
 317                         <entry><filename>/usr/lib/systemd/system</filename></entry>
 318                         <entry>Units of installed packages</entry>
 319                       </row>
 320                     </tbody>
 321                   </tgroup>
 322                 </table>
 323
 324                 <table>
 325                   <title>
 326                     Load path when running in user mode (<option>--user</option>).
 327                   </title>
 328
 329                   <tgroup cols='2'>
 330                     <colspec colname='path' />
 331                     <colspec colname='expl' />
 332                     <thead>
 333                       <row>
 334                         <entry>Path</entry>
 335                         <entry>Description</entry>
 336                       </row>
 337                     </thead>
 338                     <tbody>
 339                       <row>
 340                         <entry><filename>$XDG_CONFIG_HOME/systemd/user</filename></entry>
 341                         <entry>User configuration (only used when $XDG_CONFIG_HOME is set)</entry>
 342                       </row>
 343                       <row>
 344                         <entry><filename>$HOME/.config/systemd/user</filename></entry>
 345                         <entry>User configuration (only used when $XDG_CONFIG_HOME is not set)</entry>
 346                       </row>
 347                       <row>
 348                         <entry><filename>/etc/systemd/user</filename></entry>
 349                         <entry>Local configuration</entry>
 350                       </row>
 351                       <row>
 352                         <entry><filename>$XDG_RUNTIME_DIR/systemd/user</filename></entry>
 353                         <entry>Runtime units (only used when $XDG_RUNTIME_DIR is set)</entry>
 354                       </row>
 355                       <row>
 356                         <entry><filename>/run/systemd/user</filename></entry>
 357                         <entry>Runtime units</entry>
 358                       </row>
 359                       <row>
 360                         <entry><filename>$XDG_DATA_HOME/systemd/user</filename></entry>
 361                         <entry>Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is set)</entry>
 362                       </row>
 363                       <row>
 364                         <entry><filename>$HOME/.local/share/systemd/user</filename></entry>
 365                         <entry>Units of packages that have been installed in the home directory (only used when $XDG_DATA_HOME is not set)</entry>
 366                       </row>
 367                       <row>
 368                         <entry><filename>/usr/lib/systemd/user</filename></entry>
 369                         <entry>Units of packages that have been installed system-wide</entry>
 370                       </row>
 371                     </tbody>
 372                   </tgroup>
 373                 </table>
 374
 375                 <para>Additional units might be loaded into systemd
 376                 ("linked") from directories not on the unit load
 377                 path. See the <command>link</command> command for
 378                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>. Also,
 379                 some units are dynamically created via generators
 380                 <ulink
 381                 url="http://www.freedesktop.org/wiki/Software/systemd/Generators/">Generators</ulink>.
 382                 </para>
 383         </refsect1>
 384
 385         <refsect1>
 386                 <title>[Unit] Section Options</title>
 387
 388                 <para>Unit file may include a [Unit] section, which
 389                 carries generic information about the unit that is not
 390                 dependent on the type of unit:</para>
 391
 392                 <variablelist class='unit-directives'>
 393
 394                         <varlistentry>
 395                                 <term><varname>Description=</varname></term>
 396                                 <listitem><para>A free-form string
 397                                 describing the unit. This is intended
 398                                 for use in UIs to show descriptive
 399                                 information along with the unit
 400                                 name. The description should contain a name
 401                                 that means something to the end user.
 402                                 <literal>Apache2 Web Server</literal> is a good
 403                                 example. Bad examples are
 404                                 <literal>high-performance light-weight HTTP
 405                                 server</literal> (too generic) or
 406                                 <literal>Apache2</literal> (too specific and
 407                                 meaningless for people who do not know
 408                                 Apache).</para></listitem>
 409                         </varlistentry>
 410
 411                         <varlistentry>
 412                                 <term><varname>Documentation=</varname></term>
 413                                 <listitem><para>A space-separated list
 414                                 of URIs referencing documentation for
 415                                 this unit or its
 416                                 configuration. Accepted are only URIs
 417                                 of the types
 418                                 <literal>http://</literal>,
 419                                 <literal>https://</literal>,
 420                                 <literal>file:</literal>,
 421                                 <literal>info:</literal>,
 422                                 <literal>man:</literal>. For more
 423                                 information about the syntax of these
 424                                 URIs, see
 425                                 <citerefentry project='man-pages'><refentrytitle>uri</refentrytitle><manvolnum>7</manvolnum></citerefentry>. The
 426                                 URIs should be listed in order of
 427                                 relevance, starting with the most
 428                                 relevant. It is a good idea to first
 429                                 reference documentation that explains
 430                                 what the unit's purpose is, followed
 431                                 by how it is configured, followed by
 432                                 any other related documentation. This
 433                                 option may be specified more than once,
 434                                 in which case the specified list of
 435                                 URIs is merged. If the empty string is
 436                                 assigned to this option, the list is
 437                                 reset and all prior assignments will
 438                                 have no effect.</para></listitem>
 439                         </varlistentry>
 440
 441                         <varlistentry>
 442                                 <term><varname>Requires=</varname></term>
 443
 444                                 <listitem><para>Configures requirement
 445                                 dependencies on other units. If this
 446                                 unit gets activated, the units listed
 447                                 here will be activated as well. If one
 448                                 of the other units gets deactivated or
 449                                 its activation fails, this unit will
 450                                 be deactivated. This option may be
 451                                 specified more than once or multiple
 452                                 space-separated units may be specified
 453                                 in one option in which case
 454                                 requirement dependencies for all
 455                                 listed names will be created. Note
 456                                 that requirement dependencies do not
 457                                 influence the order in which services
 458                                 are started or stopped. This has to be
 459                                 configured independently with the
 460                                 <varname>After=</varname> or
 461                                 <varname>Before=</varname> options. If
 462                                 a unit
 463                                 <filename>foo.service</filename>
 464                                 requires a unit
 465                                 <filename>bar.service</filename> as
 466                                 configured with
 467                                 <varname>Requires=</varname> and no
 468                                 ordering is configured with
 469                                 <varname>After=</varname> or
 470                                 <varname>Before=</varname>, then both
 471                                 units will be started simultaneously
 472                                 and without any delay between them if
 473                                 <filename>foo.service</filename> is
 474                                 activated. Often it is a better choice
 475                                 to use <varname>Wants=</varname>
 476                                 instead of
 477                                 <varname>Requires=</varname> in order
 478                                 to achieve a system that is more
 479                                 robust when dealing with failing
 480                                 services.</para>
 481
 482                                 <para>Note that dependencies of this
 483                                 type may also be configured outside of
 484                                 the unit configuration file by
 485                                 adding a symlink to a
 486                                 <filename>.requires/</filename> directory
 487                                 accompanying the unit file. For
 488                                 details see above.</para></listitem>
 489                         </varlistentry>
 490
 491                         <varlistentry>
 492                                 <term><varname>RequiresOverridable=</varname></term>
 493
 494                                 <listitem><para>Similar to
 495                                 <varname>Requires=</varname>.
 496                                 Dependencies listed in
 497                                 <varname>RequiresOverridable=</varname>
 498                                 which cannot be fulfilled or fail to
 499                                 start are ignored if the startup was
 500                                 explicitly requested by the user. If
 501                                 the start-up was pulled in indirectly
 502                                 by some dependency or automatic
 503                                 start-up of units that is not
 504                                 requested by the user, this dependency
 505                                 must be fulfilled and otherwise the
 506                                 transaction fails. Hence, this option
 507                                 may be used to configure dependencies
 508                                 that are normally honored unless the
 509                                 user explicitly starts up the unit, in
 510                                 which case whether they failed or not
 511                                 is irrelevant.</para></listitem>
 512
 513                         </varlistentry>
 514                         <varlistentry>
 515                                 <term><varname>Requisite=</varname></term>
 516                                 <term><varname>RequisiteOverridable=</varname></term>
 517
 518                                 <listitem><para>Similar to
 519                                 <varname>Requires=</varname> and
 520                                 <varname>RequiresOverridable=</varname>,
 521                                 respectively. However, if the units
 522                                 listed here are not started already,
 523                                 they will not be started and the
 524                                 transaction will fail immediately.
 525                                 </para></listitem>
 526                         </varlistentry>
 527
 528                         <varlistentry>
 529                                 <term><varname>Wants=</varname></term>
 530
 531                                 <listitem><para>A weaker version of
 532                                 <varname>Requires=</varname>. Units
 533                                 listed in this option will be started
 534                                 if the configuring unit is. However,
 535                                 if the listed units fail to start
 536                                 or cannot be added to the transaction,
 537                                 this has no impact on the validity of
 538                                 the transaction as a whole. This is
 539                                 the recommended way to hook start-up
 540                                 of one unit to the start-up of another
 541                                 unit.</para>
 542
 543                                 <para>Note that dependencies of this
 544                                 type may also be configured outside of
 545                                 the unit configuration file by adding
 546                                 symlinks to a
 547                                 <filename>.wants/</filename> directory
 548                                 accompanying the unit file. For
 549                                 details, see above.</para></listitem>
 550                         </varlistentry>
 551
 552                         <varlistentry>
 553                                 <term><varname>BindsTo=</varname></term>
 554
 555                                 <listitem><para>Configures requirement
 556                                 dependencies, very similar in style to
 557                                 <varname>Requires=</varname>, however
 558                                 in addition to this behavior, it also
 559                                 declares that this unit is stopped
 560                                 when any of the units listed suddenly
 561                                 disappears. Units can suddenly,
 562                                 unexpectedly disappear if a service
 563                                 terminates on its own choice, a device
 564                                 is unplugged or a mount point
 565                                 unmounted without involvement of
 566                                 systemd.</para></listitem>
 567                         </varlistentry>
 568
 569                         <varlistentry>
 570                                 <term><varname>PartOf=</varname></term>
 571
 572                                 <listitem><para>Configures dependencies
 573                                 similar to <varname>Requires=</varname>,
 574                                 but limited to stopping and restarting
 575                                 of units. When systemd stops or restarts
 576                                 the units listed here, the action is
 577                                 propagated to this unit.
 578                                 Note that this is a one-way dependency —
 579                                 changes to this unit do not affect the
 580                                 listed units.
 581                                 </para></listitem>
 582                         </varlistentry>
 583
 584                         <varlistentry>
 585                                 <term><varname>Conflicts=</varname></term>
 586
 587                                 <listitem><para>A space-separated list
 588                                 of unit names. Configures negative
 589                                 requirement dependencies. If a unit
 590                                 has a <varname>Conflicts=</varname>
 591                                 setting on another unit, starting the
 592                                 former will stop the latter and vice
 593                                 versa. Note that this setting is
 594                                 independent of and orthogonal to the
 595                                 <varname>After=</varname> and
 596                                 <varname>Before=</varname> ordering
 597                                 dependencies.</para>
 598
 599                                 <para>If a unit A that conflicts with
 600                                 a unit B is scheduled to be started at
 601                                 the same time as B, the transaction
 602                                 will either fail (in case both are
 603                                 required part of the transaction) or
 604                                 be modified to be fixed (in case one
 605                                 or both jobs are not a required part
 606                                 of the transaction). In the latter
 607                                 case, the job that is not the required
 608                                 will be removed, or in case both are
 609                                 not required, the unit that conflicts
 610                                 will be started and the unit that is
 611                                 conflicted is
 612                                 stopped.</para></listitem>
 613                         </varlistentry>
 614
 615                         <varlistentry>
 616                                 <term><varname>Before=</varname></term>
 617                                 <term><varname>After=</varname></term>
 618
 619                                 <listitem><para>A space-separated list
 620                                 of unit names. Configures ordering
 621                                 dependencies between units. If a unit
 622                                 <filename>foo.service</filename>
 623                                 contains a setting
 624                                 <option>Before=bar.service</option>
 625                                 and both units are being started,
 626                                 <filename>bar.service</filename>'s
 627                                 start-up is delayed until
 628                                 <filename>foo.service</filename> is
 629                                 started up. Note that this setting is
 630                                 independent of and orthogonal to the
 631                                 requirement dependencies as configured
 632                                 by <varname>Requires=</varname>. It is
 633                                 a common pattern to include a unit
 634                                 name in both the
 635                                 <varname>After=</varname> and
 636                                 <varname>Requires=</varname> option, in
 637                                 which case the unit listed will be
 638                                 started before the unit that is
 639                                 configured with these options. This
 640                                 option may be specified more than
 641                                 once, in which case ordering
 642                                 dependencies for all listed names are
 643                                 created. <varname>After=</varname> is
 644                                 the inverse of
 645                                 <varname>Before=</varname>, i.e. while
 646                                 <varname>After=</varname> ensures that
 647                                 the configured unit is started after
 648                                 the listed unit finished starting up,
 649                                 <varname>Before=</varname> ensures the
 650                                 opposite, i.e.  that the configured
 651                                 unit is fully started up before the
 652                                 listed unit is started. Note that when
 653                                 two units with an ordering dependency
 654                                 between them are shut down, the
 655                                 inverse of the start-up order is
 656                                 applied. i.e. if a unit is configured
 657                                 with <varname>After=</varname> on
 658                                 another unit, the former is stopped
 659                                 before the latter if both are shut
 660                                 down. If one unit with an ordering
 661                                 dependency on another unit is shut
 662                                 down while the latter is started up,
 663                                 the shut down is ordered before the
 664                                 start-up regardless of whether the
 665                                 ordering dependency is actually of
 666                                 type <varname>After=</varname> or
 667                                 <varname>Before=</varname>. If two
 668                                 units have no ordering dependencies
 669                                 between them, they are shut down or
 670                                 started up simultaneously, and no
 671                                 ordering takes
 672                                 place. </para></listitem>
 673                         </varlistentry>
 674
 675                         <varlistentry>
 676                                 <term><varname>OnFailure=</varname></term>
 677
 678                                 <listitem><para>A space-separated list
 679                                 of one or more units that are
 680                                 activated when this unit enters the
 681                                 <literal>failed</literal>
 682                                 state.</para></listitem>
 683                         </varlistentry>
 684
 685                         <varlistentry>
 686                                 <term><varname>PropagatesReloadTo=</varname></term>
 687                                 <term><varname>ReloadPropagatedFrom=</varname></term>
 688
 689                                 <listitem><para>A space-separated list
 690                                 of one or more units where reload
 691                                 requests on this unit will be
 692                                 propagated to, or reload requests on
 693                                 the other unit will be propagated to
 694                                 this unit, respectively. Issuing a
 695                                 reload request on a unit will
 696                                 automatically also enqueue a reload
 697                                 request on all units that the reload
 698                                 request shall be propagated to via
 699                                 these two settings.</para></listitem>
 700                         </varlistentry>
 701
 702                         <varlistentry>
 703                                 <term><varname>JoinsNamespaceOf=</varname></term>
 704
 705                                 <listitem><para>For units that start
 706                                 processes (such as service units),
 707                                 lists one or more other units whose
 708                                 network and/or temporary file
 709                                 namespace to join. This only applies
 710                                 to unit types which support the
 711                                 <varname>PrivateNetwork=</varname> and
 712                                 <varname>PrivateTmp=</varname>
 713                                 directives (see
 714                                 <citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 715                                 for details). If a unit that has this
 716                                 setting set is started, its processes
 717                                 will see the same
 718                                 <filename>/tmp</filename>,
 719                                 <filename>/tmp/var</filename> and
 720                                 network namespace as one listed unit
 721                                 that is started. If multiple listed
 722                                 units are already started, it is not
 723                                 defined which namespace is
 724                                 joined. Note that this setting only
 725                                 has an effect if
 726                                 <varname>PrivateNetwork=</varname>
 727                                 and/or <varname>PrivateTmp=</varname>
 728                                 is enabled for both the unit that
 729                                 joins the namespace and the unit whose
 730                                 namespace is joined.</para></listitem>
 731                         </varlistentry>
 732
 733                         <varlistentry>
 734                                 <term><varname>RequiresMountsFor=</varname></term>
 735
 736                                 <listitem><para>Takes a
 737                                 space-separated list of absolute
 738                                 paths. Automatically adds dependencies
 739                                 of type <varname>Requires=</varname>
 740                                 and <varname>After=</varname> for all
 741                                 mount units required to access the
 742                                 specified path.</para>
 743
 744                                 <para>Mount points marked with
 745                                 <option>noauto</option> are not
 746                                 mounted automatically and will be
 747                                 ignored for the purposes of this
 748                                 option. If such a mount should be a
 749                                 requirement for this unit,
 750                                 direct dependencies on the mount
 751                                 units may be added
 752                                 (<varname>Requires=</varname> and
 753                                 <varname>After=</varname> or
 754                                 some other combination).
 755                                 </para></listitem>
 756                         </varlistentry>
 757
 758                         <varlistentry>
 759                                 <term><varname>OnFailureJobMode=</varname></term>
 760
 761                                 <listitem><para>Takes a value of
 762                                 <literal>fail</literal>,
 763                                 <literal>replace</literal>,
 764                                 <literal>replace-irreversibly</literal>,
 765                                 <literal>isolate</literal>,
 766                                 <literal>flush</literal>,
 767                                 <literal>ignore-dependencies</literal>
 768                                 or
 769                                 <literal>ignore-requirements</literal>. Defaults
 770                                 to
 771                                 <literal>replace</literal>. Specifies
 772                                 how the units listed in
 773                                 <varname>OnFailure=</varname> will be
 774                                 enqueued. See
 775                                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 776                                 <option>--job-mode=</option> option
 777                                 for details on the possible values. If
 778                                 this is set to
 779                                 <literal>isolate</literal>, only a
 780                                 single unit may be listed in
 781                                 <varname>OnFailure=</varname>..</para></listitem>
 782                         </varlistentry>
 783
 784                         <varlistentry>
 785                                 <term><varname>IgnoreOnIsolate=</varname></term>
 786
 787                                 <listitem><para>Takes a boolean
 788                                 argument. If <option>true</option>,
 789                                 this unit will not be stopped when
 790                                 isolating another unit. Defaults to
 791                                 <option>false</option>.</para></listitem>
 792                         </varlistentry>
 793
 794                         <varlistentry>
 795                                 <term><varname>IgnoreOnSnapshot=</varname></term>
 796
 797                                 <listitem><para>Takes a boolean
 798                                 argument. If <option>true</option>,
 799                                 this unit will not be included in
 800                                 snapshots. Defaults to
 801                                 <option>true</option> for device and
 802                                 snapshot units, <option>false</option>
 803                                 for the others.</para></listitem>
 804                         </varlistentry>
 805
 806                         <varlistentry>
 807                                 <term><varname>StopWhenUnneeded=</varname></term>
 808
 809                                 <listitem><para>Takes a boolean
 810                                 argument. If <option>true</option>,
 811                                 this unit will be stopped when it is
 812                                 no longer used. Note that in order to
 813                                 minimize the work to be executed,
 814                                 systemd will not stop units by default
 815                                 unless they are conflicting with other
 816                                 units, or the user explicitly
 817                                 requested their shut down. If this
 818                                 option is set, a unit will be
 819                                 automatically cleaned up if no other
 820                                 active unit requires it. Defaults to
 821                                 <option>false</option>.</para></listitem>
 822                         </varlistentry>
 823
 824                         <varlistentry>
 825                                 <term><varname>RefuseManualStart=</varname></term>
 826                                 <term><varname>RefuseManualStop=</varname></term>
 827
 828                                 <listitem><para>Takes a boolean
 829                                 argument. If <option>true</option>,
 830                                 this unit can only be activated
 831                                 or deactivated indirectly. In
 832                                 this case, explicit start-up
 833                                 or termination requested by the
 834                                 user is denied, however if it is
 835                                 started or stopped as a
 836                                 dependency of another unit, start-up
 837                                 or termination will succeed. This
 838                                 is mostly a safety feature to ensure
 839                                 that the user does not accidentally
 840                                 activate units that are not intended
 841                                 to be activated explicitly, and not
 842                                 accidentally deactivate units that are
 843                                 not intended to be deactivated.
 844                                 These options default to
 845                                 <option>false</option>.</para></listitem>
 846                         </varlistentry>
 847
 848                         <varlistentry>
 849                                 <term><varname>AllowIsolate=</varname></term>
 850
 851                                 <listitem><para>Takes a boolean
 852                                 argument. If <option>true</option>,
 853                                 this unit may be used with the
 854                                 <command>systemctl isolate</command>
 855                                 command. Otherwise, this will be
 856                                 refused. It probably is a good idea to
 857                                 leave this disabled except for target
 858                                 units that shall be used similar to
 859                                 runlevels in SysV init systems, just
 860                                 as a precaution to avoid unusable
 861                                 system states. This option defaults to
 862                                 <option>false</option>.</para></listitem>
 863                         </varlistentry>
 864
 865                         <varlistentry>
 866                                 <term><varname>DefaultDependencies=</varname></term>
 867
 868                                 <listitem><para>Takes a boolean
 869                                 argument. If <option>true</option>,
 870                                 (the default), a few default
 871                                 dependencies will implicitly be
 872                                 created for the unit. The actual
 873                                 dependencies created depend on the
 874                                 unit type. For example, for service
 875                                 units, these dependencies ensure that
 876                                 the service is started only after
 877                                 basic system initialization is
 878                                 completed and is properly terminated on
 879                                 system shutdown. See the respective
 880                                 man pages for details. Generally, only
 881                                 services involved with early boot or
 882                                 late shutdown should set this option
 883                                 to <option>false</option>. It is
 884                                 highly recommended to leave this
 885                                 option enabled for the majority of
 886                                 common units. If set to
 887                                 <option>false</option>, this option
 888                                 does not disable all implicit
 889                                 dependencies, just non-essential
 890                                 ones.</para></listitem>
 891                         </varlistentry>
 892
 893                         <varlistentry>
 894                                 <term><varname>JobTimeoutSec=</varname></term>
 895                                 <term><varname>JobTimeoutAction=</varname></term>
 896                                 <term><varname>JobTimeoutRebootArgument=</varname></term>
 897
 898                                 <listitem><para>When a job for this
 899                                 unit is queued a time-out may be
 900                                 configured. If this time limit is
 901                                 reached, the job will be cancelled,
 902                                 the unit however will not change state
 903                                 or even enter the
 904                                 <literal>failed</literal> mode. This
 905                                 value defaults to 0 (job timeouts
 906                                 disabled), except for device
 907                                 units. NB: this timeout is independent
 908                                 from any unit-specific timeout (for
 909                                 example, the timeout set with
 910                                 <varname>StartTimeoutSec=</varname> in service
 911                                 units) as the job timeout has no
 912                                 effect on the unit itself, only on the
 913                                 job that might be pending for it. Or
 914                                 in other words: unit-specific timeouts
 915                                 are useful to abort unit state
 916                                 changes, and revert them. The job
 917                                 timeout set with this option however
 918                                 is useful to abort only the job
 919                                 waiting for the unit state to
 920                                 change.</para>
 921
 922                                 <para><varname>JobTimeoutAction=</varname>
 923                                 optionally configures an additional
 924                                 action to take when the time-out is
 925                                 hit. It takes the same values as the
 926                                 per-service
 927                                 <varname>StartLimitAction=</varname>
 928                                 setting, see
 929                                 <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 930                                 for details. Defaults to
 931                                 <option>none</option>. <varname>JobTimeoutRebootArgument=</varname>
 932                                 configures an optional reboot string
 933                                 to pass to the
 934                                 <citerefentry><refentrytitle>reboot</refentrytitle><manvolnum>2</manvolnum></citerefentry>
 935                                 system call.</para></listitem>
 936                         </varlistentry>
 937
 938                         <varlistentry>
 939                                 <term><varname>ConditionArchitecture=</varname></term>
 940                                 <term><varname>ConditionVirtualization=</varname></term>
 941                                 <term><varname>ConditionHost=</varname></term>
 942                                 <term><varname>ConditionKernelCommandLine=</varname></term>
 943                                 <term><varname>ConditionSecurity=</varname></term>
 944                                 <term><varname>ConditionCapability=</varname></term>
 945                                 <term><varname>ConditionACPower=</varname></term>
 946                                 <term><varname>ConditionNeedsUpdate=</varname></term>
 947                                 <term><varname>ConditionFirstBoot=</varname></term>
 948                                 <term><varname>ConditionPathExists=</varname></term>
 949                                 <term><varname>ConditionPathExistsGlob=</varname></term>
 950                                 <term><varname>ConditionPathIsDirectory=</varname></term>
 951                                 <term><varname>ConditionPathIsSymbolicLink=</varname></term>
 952                                 <term><varname>ConditionPathIsMountPoint=</varname></term>
 953                                 <term><varname>ConditionPathIsReadWrite=</varname></term>
 954                                 <term><varname>ConditionDirectoryNotEmpty=</varname></term>
 955                                 <term><varname>ConditionFileNotEmpty=</varname></term>
 956                                 <term><varname>ConditionFileIsExecutable=</varname></term>
 957
 958                                 <!-- We don't document ConditionNull=
 959                                      here as it is not particularly
 960                                      useful and probably just
 961                                      confusing. -->
 962
 963                                 <listitem><para>Before starting a unit
 964                                 verify that the specified condition is
 965                                 true. If it is not true, the starting
 966                                 of the unit will be skipped, however
 967                                 all ordering dependencies of it are
 968                                 still respected. A failing condition
 969                                 will not result in the unit being
 970                                 moved into a failure state. The
 971                                 condition is checked at the time the
 972                                 queued start job is to be
 973                                 executed.</para>
 974
 975                                 <para><varname>ConditionArchitecture=</varname>
 976                                 may be used to check whether the
 977                                 system is running on a specific
 978                                 architecture. Takes one of
 979                                 <varname>x86</varname>,
 980                                 <varname>x86-64</varname>,
 981                                 <varname>ppc</varname>,
 982                                 <varname>ppc-le</varname>,
 983                                 <varname>ppc64</varname>,
 984                                 <varname>ppc64-le</varname>,
 985                                 <varname>ia64</varname>,
 986                                 <varname>parisc</varname>,
 987                                 <varname>parisc64</varname>,
 988                                 <varname>s390</varname>,
 989                                 <varname>s390x</varname>,
 990                                 <varname>sparc</varname>,
 991                                 <varname>sparc64</varname>,
 992                                 <varname>mips</varname>,
 993                                 <varname>mips-le</varname>,
 994                                 <varname>mips64</varname>,
 995                                 <varname>mips64-le</varname>,
 996                                 <varname>alpha</varname>,
 997                                 <varname>arm</varname>,
 998                                 <varname>arm-be</varname>,
 999                                 <varname>arm64</varname>,
1000                                 <varname>arm64-be</varname>,
1001                                 <varname>sh</varname>,
1002                                 <varname>sh64</varname>,
1003                                 <varname>m86k</varname>,
1004                                 <varname>tilegx</varname>,
1005                                 <varname>cris</varname> to test
1006                                 against a specific architecture. The
1007                                 architecture is determined from the
1008                                 information returned by
1009                                 <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>2</manvolnum></citerefentry>
1010                                 and is thus subject to
1011                                 <citerefentry><refentrytitle>personality</refentrytitle><manvolnum>2</manvolnum></citerefentry>. Note
1012                                 that a <varname>Personality=</varname>
1013                                 setting in the same unit file has no
1014                                 effect on this condition. A special
1015                                 architecture name
1016                                 <varname>native</varname> is mapped to
1017                                 the architecture the system manager
1018                                 itself is compiled for. The test may
1019                                 be negated by prepending an
1020                                 exclamation mark.</para>
1021
1022                                 <para><varname>ConditionVirtualization=</varname>
1023                                 may be used to check whether the
1024                                 system is executed in a virtualized
1025                                 environment and optionally test
1026                                 whether it is a specific
1027                                 implementation. Takes either boolean
1028                                 value to check if being executed in
1029                                 any virtualized environment, or one of
1030                                 <varname>vm</varname> and
1031                                 <varname>container</varname> to test
1032                                 against a generic type of
1033                                 virtualization solution, or one of
1034                                 <varname>qemu</varname>,
1035                                 <varname>kvm</varname>,
1036                                 <varname>zvm</varname>,
1037                                 <varname>vmware</varname>,
1038                                 <varname>microsoft</varname>,
1039                                 <varname>oracle</varname>,
1040                                 <varname>xen</varname>,
1041                                 <varname>bochs</varname>,
1042                                 <varname>uml</varname>,
1043                                 <varname>openvz</varname>,
1044                                 <varname>lxc</varname>,
1045                                 <varname>lxc-libvirt</varname>,
1046                                 <varname>systemd-nspawn</varname>,
1047                                 <varname>docker</varname> to test
1048                                 against a specific implementation. See
1049                                 <citerefentry><refentrytitle>systemd-detect-virt</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1050                                 for a full list of known
1051                                 virtualization technologies and their
1052                                 identifiers. If multiple
1053                                 virtualization technologies are
1054                                 nested, only the innermost is
1055                                 considered. The test may be negated by
1056                                 prepending an exclamation mark.</para>
1057
1058                                 <para><varname>ConditionHost=</varname>
1059                                 may be used to match against the
1060                                 hostname or machine ID of the
1061                                 host. This either takes a hostname
1062                                 string (optionally with shell style
1063                                 globs) which is tested against the
1064                                 locally set hostname as returned by
1065                                 <citerefentry><refentrytitle>gethostname</refentrytitle><manvolnum>2</manvolnum></citerefentry>,
1066                                 or a machine ID formatted as string
1067                                 (see
1068                                 <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
1069                                 The test may be negated by prepending
1070                                 an exclamation mark.</para>
1071
1072                                 <para><varname>ConditionKernelCommandLine=</varname>
1073                                 may be used to check whether a
1074                                 specific kernel command line option is
1075                                 set (or if prefixed with the
1076                                 exclamation mark unset). The argument
1077                                 must either be a single word, or an
1078                                 assignment (i.e. two words, separated
1079                                 <literal>=</literal>). In the former
1080                                 case the kernel command line is
1081                                 searched for the word appearing as is,
1082                                 or as left hand side of an
1083                                 assignment. In the latter case, the
1084                                 exact assignment is looked for with
1085                                 right and left hand side
1086                                 matching.</para>
1087
1088                                 <para><varname>ConditionSecurity=</varname>
1089                                 may be used to check whether the given
1090                                 security module is enabled on the
1091                                 system. Currently the recognized
1092                                 values values are
1093                                 <varname>selinux</varname>,
1094                                 <varname>apparmor</varname>,
1095                                 <varname>ima</varname>,
1096                                 <varname>smack</varname> and
1097                                 <varname>audit</varname>. The test may
1098                                 be negated by prepending an
1099                                 exclamation mark.</para>
1100
1101                                 <para><varname>ConditionCapability=</varname>
1102                                 may be used to check whether the given
1103                                 capability exists in the capability
1104                                 bounding set of the service manager
1105                                 (i.e. this does not check whether
1106                                 capability is actually available in
1107                                 the permitted or effective sets, see
1108                                 <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1109                                 for details). Pass a capability name
1110                                 such as <literal>CAP_MKNOD</literal>,
1111                                 possibly prefixed with an exclamation
1112                                 mark to negate the check.</para>
1113
1114                                 <para><varname>ConditionACPower=</varname>
1115                                 may be used to check whether the
1116                                 system has AC power, or is exclusively
1117                                 battery powered at the time of
1118                                 activation of the unit. This takes a
1119                                 boolean argument. If set to
1120                                 <varname>true</varname>, the condition
1121                                 will hold only if at least one AC
1122                                 connector of the system is connected
1123                                 to a power source, or if no AC
1124                                 connectors are known. Conversely, if
1125                                 set to <varname>false</varname>, the
1126                                 condition will hold only if there is
1127                                 at least one AC connector known and
1128                                 all AC connectors are disconnected
1129                                 from a power source.</para>
1130
1131                                 <para><varname>ConditionNeedsUpdate=</varname>
1132                                 takes one of <filename>/var</filename>
1133                                 or <filename>/etc</filename> as
1134                                 argument, possibly prefixed with a
1135                                 <literal>!</literal> (for inverting
1136                                 the condition). This condition may be
1137                                 used to conditionalize units on
1138                                 whether the specified directory
1139                                 requires an update because
1140                                 <filename>/usr</filename>'s
1141                                 modification time is newer than the
1142                                 stamp file
1143                                 <filename>.updated</filename> in the
1144                                 specified directory. This is useful to
1145                                 implement offline updates of the
1146                                 vendor operating system resources in
1147                                 <filename>/usr</filename> that require
1148                                 updating of <filename>/etc</filename>
1149                                 or <filename>/var</filename> on the
1150                                 next following boot. Units making use
1151                                 of this condition should order
1152                                 themselves before
1153                                 <citerefentry><refentrytitle>systemd-update-done.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1154                                 to make sure they run before the stamp
1155                                 files's modification time gets reset
1156                                 indicating a completed update.</para>
1157
1158                                 <para><varname>ConditionFirstBoot=</varname>
1159                                 takes a boolean argument. This
1160                                 condition may be used to
1161                                 conditionalize units on whether the
1162                                 system is booting up with an
1163                                 unpopulated <filename>/etc</filename>
1164                                 directory. This may be used to
1165                                 populate <filename>/etc</filename> on
1166                                 the first boot after factory reset, or
1167                                 when a new system instances boots up
1168                                 for the first time.</para>
1169
1170                                 <para>With
1171                                 <varname>ConditionPathExists=</varname>
1172                                 a file existence condition is
1173                                 checked before a unit is started. If
1174                                 the specified absolute path name does
1175                                 not exist, the condition will
1176                                 fail. If the absolute path name passed
1177                                 to
1178                                 <varname>ConditionPathExists=</varname>
1179                                 is prefixed with an exclamation mark
1180                                 (<literal>!</literal>), the test is negated, and the unit
1181                                 is only started if the path does not
1182                                 exist.</para>
1183
1184                                 <para><varname>ConditionPathExistsGlob=</varname>
1185                                 is similar to
1186                                 <varname>ConditionPathExists=</varname>,
1187                                 but checks for the existence of at
1188                                 least one file or directory matching
1189                                 the specified globbing pattern.</para>
1190
1191                                 <para><varname>ConditionPathIsDirectory=</varname>
1192                                 is similar to
1193                                 <varname>ConditionPathExists=</varname>
1194                                 but verifies whether a certain path
1195                                 exists and is a
1196                                 directory.</para>
1197
1198                                 <para><varname>ConditionPathIsSymbolicLink=</varname>
1199                                 is similar to
1200                                 <varname>ConditionPathExists=</varname>
1201                                 but verifies whether a certain path
1202                                 exists and is a symbolic
1203                                 link.</para>
1204
1205                                 <para><varname>ConditionPathIsMountPoint=</varname>
1206                                 is similar to
1207                                 <varname>ConditionPathExists=</varname>
1208                                 but verifies whether a certain path
1209                                 exists and is a mount
1210                                 point.</para>
1211
1212                                 <para><varname>ConditionPathIsReadWrite=</varname>
1213                                 is similar to
1214                                 <varname>ConditionPathExists=</varname>
1215                                 but verifies whether the underlying
1216                                 file system is readable and writable
1217                                 (i.e. not mounted
1218                                 read-only).</para>
1219
1220                                 <para><varname>ConditionDirectoryNotEmpty=</varname>
1221                                 is similar to
1222                                 <varname>ConditionPathExists=</varname>
1223                                 but verifies whether a certain path
1224                                 exists and is a non-empty
1225                                 directory.</para>
1226
1227                                 <para><varname>ConditionFileNotEmpty=</varname>
1228                                 is similar to
1229                                 <varname>ConditionPathExists=</varname>
1230                                 but verifies whether a certain path
1231                                 exists and refers to a regular file
1232                                 with a non-zero size.</para>
1233
1234                                 <para><varname>ConditionFileIsExecutable=</varname>
1235                                 is similar to
1236                                 <varname>ConditionPathExists=</varname>
1237                                 but verifies whether a certain path
1238                                 exists, is a regular file and marked
1239                                 executable.</para>
1240
1241                                 <para>If multiple conditions are
1242                                 specified, the unit will be executed if
1243                                 all of them apply (i.e. a logical AND
1244                                 is applied). Condition checks can be
1245                                 prefixed with a pipe symbol (|) in
1246                                 which case a condition becomes a
1247                                 triggering condition. If at least one
1248                                 triggering condition is defined for a
1249                                 unit, then the unit will be executed if
1250                                 at least one of the triggering
1251                                 conditions apply and all of the
1252                                 non-triggering conditions. If you
1253                                 prefix an argument with the pipe
1254                                 symbol and an exclamation mark, the
1255                                 pipe symbol must be passed first, the
1256                                 exclamation second. Except for
1257                                 <varname>ConditionPathIsSymbolicLink=</varname>,
1258                                 all path checks follow symlinks. If
1259                                 any of these options is assigned the
1260                                 empty string, the list of conditions is
1261                                 reset completely, all previous
1262                                 condition settings (of any kind) will
1263                                 have no effect.</para></listitem>
1264                         </varlistentry>
1265
1266                         <varlistentry>
1267                                 <term><varname>AssertArchitecture=</varname></term>
1268                                 <term><varname>AssertVirtualization=</varname></term>
1269                                 <term><varname>AssertHost=</varname></term>
1270                                 <term><varname>AssertKernelCommandLine=</varname></term>
1271                                 <term><varname>AssertSecurity=</varname></term>
1272                                 <term><varname>AssertCapability=</varname></term>
1273                                 <term><varname>AssertACPower=</varname></term>
1274                                 <term><varname>AssertNeedsUpdate=</varname></term>
1275                                 <term><varname>AssertFirstBoot=</varname></term>
1276                                 <term><varname>AssertPathExists=</varname></term>
1277                                 <term><varname>AssertPathExistsGlob=</varname></term>
1278                                 <term><varname>AssertPathIsDirectory=</varname></term>
1279                                 <term><varname>AssertPathIsSymbolicLink=</varname></term>
1280                                 <term><varname>AssertPathIsMountPoint=</varname></term>
1281                                 <term><varname>AssertPathIsReadWrite=</varname></term>
1282                                 <term><varname>AssertDirectoryNotEmpty=</varname></term>
1283                                 <term><varname>AssertFileNotEmpty=</varname></term>
1284                                 <term><varname>AssertFileIsExecutable=</varname></term>
1285
1286                                 <listitem><para>Similar to the
1287                                 <varname>ConditionArchitecture=</varname>,
1288                                 <varname>ConditionVirtualization=</varname>,
1289                                 ... condition settings described above
1290                                 these settings add assertion checks to
1291                                 the start-up of the unit. However,
1292                                 unlike the conditions settings any
1293                                 assertion setting that is not met
1294                                 results in failure of the start
1295                                 job it was triggered by.</para></listitem>
1296                         </varlistentry>
1297
1298                         <varlistentry>
1299                                 <term><varname>SourcePath=</varname></term>
1300                                 <listitem><para>A path to a
1301                                 configuration file this unit has been
1302                                 generated from. This is primarily
1303                                 useful for implementation of generator
1304                                 tools that convert configuration from
1305                                 an external configuration file format
1306                                 into native unit files. This
1307                                 functionality should not be used in
1308                                 normal units.</para></listitem>
1309                         </varlistentry>
1310                 </variablelist>
1311
1312         </refsect1>
1313
1314         <refsect1>
1315                 <title>[Install] Section Options</title>
1316
1317                 <para>Unit file may include an
1318                 <literal>[Install]</literal> section, which carries
1319                 installation information for the unit. This section is
1320                 not interpreted by
1321                 <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1322                 during runtime. It is used exclusively by the
1323                 <command>enable</command> and
1324                 <command>disable</command> commands of the
1325                 <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1326                 tool during installation of a unit:</para>
1327
1328                 <variablelist class='unit-directives'>
1329                         <varlistentry>
1330                                 <term><varname>Alias=</varname></term>
1331
1332                                 <listitem><para>A space-separated list
1333                                 of additional names this unit shall be
1334                                 installed under. The names listed here
1335                                 must have the same suffix (i.e. type)
1336                                 as the unit file name. This option may
1337                                 be specified more than once, in which
1338                                 case all listed names are used. At
1339                                 installation time, <command>systemctl
1340                                 enable</command> will create symlinks
1341                                 from these names to the unit
1342                                 filename.</para></listitem>
1343                         </varlistentry>
1344
1345                         <varlistentry>
1346                                 <term><varname>WantedBy=</varname></term>
1347                                 <term><varname>RequiredBy=</varname></term>
1348
1349                                 <listitem><para>This option may be
1350                                 used more than once, or a
1351                                 space-separated list of unit names may
1352                                 be given. A symbolic link is created
1353                                 in the <filename>.wants/</filename> or
1354                                 <filename>.requires/</filename>
1355                                 directory of each of the listed units
1356                                 when this unit is installed by
1357                                 <command>systemctl enable</command>.
1358                                 This has the effect that a dependency
1359                                 of type <varname>Wants=</varname> or
1360                                 <varname>Requires=</varname> is added
1361                                 from the listed unit to the current
1362                                 unit. The primary result is that the
1363                                 current unit will be started when the
1364                                 listed unit is started. See the
1365                                 description of
1366                                 <varname>Wants=</varname> and
1367                                 <varname>Requires=</varname> in the
1368                                 [Unit] section for details.</para>
1369
1370                                 <para><command>WantedBy=foo.service</command>
1371                                 in a service
1372                                 <filename>bar.service</filename> is
1373                                 mostly equivalent to
1374                                 <command>Alias=foo.service.wants/bar.service</command>
1375                                 in the same file. In case of template
1376                                 units, <command>systemctl enable</command>
1377                                 must be called with an instance name, and
1378                                 this instance will be added to the
1379                                 <filename>.wants/</filename> or
1380                                 <filename>.requires/</filename> list
1381                                 of the listed unit.
1382                                 E.g. <command>WantedBy=getty.target</command>
1383                                 in a service
1384                                 <filename>getty@.service</filename>
1385                                 will result in <command>systemctl
1386                                 enable getty@tty2.service</command>
1387                                 creating a
1388                                 <filename>getty.target.wants/getty@tty2.service</filename>
1389                                 link to <filename>getty@.service</filename>.
1390                                 </para></listitem>
1391                         </varlistentry>
1392
1393                         <varlistentry>
1394                                 <term><varname>Also=</varname></term>
1395
1396                                 <listitem><para>Additional units to
1397                                 install/deinstall when this unit is
1398                                 installed/deinstalled. If the user
1399                                 requests installation/deinstallation
1400                                 of a unit with this option configured,
1401                                 <command>systemctl enable</command>
1402                                 and <command>systemctl
1403                                 disable</command> will automatically
1404                                 install/uninstall units listed in this option as
1405                                 well.</para>
1406
1407                                 <para>This option may be used more
1408                                 than once, or a space-separated list
1409                                 of unit names may be
1410                                 given.</para></listitem>
1411                         </varlistentry>
1412
1413                         <varlistentry>
1414                                 <term><varname>DefaultInstance=</varname></term>
1415
1416                                 <listitem><para>In template unit files,
1417                                 this specifies for which instance the
1418                                 unit shall be enabled if the template
1419                                 is enabled without any explicitly set
1420                                 instance. This option has no effect in
1421                                 non-template unit files. The specified
1422                                 string must be usable as instance
1423                                 identifier.</para></listitem>
1424                         </varlistentry>
1425                 </variablelist>
1426
1427                 <para>The following specifiers are interpreted in the
1428                 Install section: %n, %N, %p, %i, %U, %u, %m, %H, %b, %v.
1429                 For their meaning see the next section.
1430                 </para>
1431         </refsect1>
1432
1433         <refsect1>
1434                 <title>Specifiers</title>
1435
1436                 <para>Many settings resolve specifiers which may be
1437                 used to write generic unit files referring to runtime
1438                 or unit parameters that are replaced when the unit
1439                 files are loaded. The following specifiers are
1440                 understood:</para>
1441
1442                 <table>
1443                   <title>Specifiers available in unit files</title>
1444                   <tgroup cols='3' align='left' colsep='1' rowsep='1'>
1445                     <colspec colname="spec" />
1446                     <colspec colname="mean" />
1447                     <colspec colname="detail" />
1448                     <thead>
1449                       <row>
1450                         <entry>Specifier</entry>
1451                         <entry>Meaning</entry>
1452                         <entry>Details</entry>
1453                       </row>
1454                     </thead>
1455                     <tbody>
1456                       <row>
1457                         <entry><literal>%n</literal></entry>
1458                         <entry>Full unit name</entry>
1459                         <entry></entry>
1460                       </row>
1461                       <row>
1462                         <entry><literal>%N</literal></entry>
1463                         <entry>Unescaped full unit name</entry>
1464                         <entry>Same as <literal>%n</literal>, but with escaping undone</entry>
1465                       </row>
1466                       <row>
1467                         <entry><literal>%p</literal></entry>
1468                         <entry>Prefix name</entry>
1469                         <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>
1470                       </row>
1471                       <row>
1472                         <entry><literal>%P</literal></entry>
1473                         <entry>Unescaped prefix name</entry>
1474                         <entry>Same as <literal>%p</literal>, but with escaping undone</entry>
1475                       </row>
1476                       <row>
1477                         <entry><literal>%i</literal></entry>
1478                         <entry>Instance name</entry>
1479                         <entry>For instantiated units: this is the string between the <literal>@</literal> character and the suffix of the unit name.</entry>
1480                       </row>
1481                       <row>
1482                         <entry><literal>%I</literal></entry>
1483                         <entry>Unescaped instance name</entry>
1484                         <entry>Same as <literal>%i</literal>, but with escaping undone</entry>
1485                       </row>
1486                       <row>
1487                         <entry><literal>%f</literal></entry>
1488                         <entry>Unescaped filename</entry>
1489                         <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>
1490                       </row>
1491                       <row>
1492                         <entry><literal>%c</literal></entry>
1493                         <entry>Control group path of the unit</entry>
1494                         <entry>This path does not include the <filename>/sys/fs/cgroup/systemd/</filename> prefix.</entry>
1495                       </row>
1496                       <row>
1497                         <entry><literal>%r</literal></entry>
1498                         <entry>Control group path of the slice the unit is placed in</entry>
1499                         <entry>This usually maps to the parent cgroup path of <literal>%c</literal>.</entry>
1500                       </row>
1501                       <row>
1502                         <entry><literal>%R</literal></entry>
1503                         <entry>Root control group path below which slices and units are placed</entry>
1504                         <entry>For system instances, this resolves to <filename>/</filename>, except in containers, where this maps to the container's root control group path.</entry>
1505                       </row>
1506                       <row>
1507                         <entry><literal>%t</literal></entry>
1508                         <entry>Runtime directory</entry>
1509                         <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>
1510                       </row>
1511                       <row>
1512                         <entry><literal>%u</literal></entry>
1513                         <entry>User name</entry>
1514                         <entry>This is the name of the configured user of the unit, or (if none is set) the user running the systemd instance.</entry>
1515                       </row>
1516                       <row>
1517                         <entry><literal>%U</literal></entry>
1518                         <entry>User UID</entry>
1519                         <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>
1520                       </row>
1521                       <row>
1522                         <entry><literal>%h</literal></entry>
1523                         <entry>User home directory</entry>
1524                         <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>
1525                       </row>
1526                       <row>
1527                         <entry><literal>%s</literal></entry>
1528                         <entry>User shell</entry>
1529                         <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>
1530                       </row>
1531                       <row>
1532                         <entry><literal>%m</literal></entry>
1533                         <entry>Machine ID</entry>
1534                         <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>
1535                       </row>
1536                       <row>
1537                         <entry><literal>%b</literal></entry>
1538                         <entry>Boot ID</entry>
1539                         <entry>The boot ID of the running system, formatted as string. See <citerefentry><refentrytitle>random</refentrytitle><manvolnum>4</manvolnum></citerefentry> for more information.</entry>
1540                       </row>
1541                       <row>
1542                         <entry><literal>%H</literal></entry>
1543                         <entry>Host name</entry>
1544                         <entry>The hostname of the running system at the point in time the unit configuation is loaded.</entry>
1545                       </row>
1546                       <row>
1547                         <entry><literal>%v</literal></entry>
1548                         <entry>Kernel release</entry>
1549                         <entry>Identical to <command>uname -r</command> output</entry>
1550                       </row>
1551                       <row>
1552                         <entry><literal>%%</literal></entry>
1553                         <entry>Single percent sign</entry>
1554                         <entry>Use <literal>%%</literal> in place of <literal>%</literal> to specify a single percent sign.</entry>
1555                       </row>
1556                     </tbody>
1557                   </tgroup>
1558                 </table>
1559
1560                 <para>Please note that specifiers
1561                 <literal>%U</literal>, <literal>%h</literal>,
1562                 <literal>%s</literal> are mostly useless when systemd
1563                 is running in system mode.  PID 1 cannot query the
1564                 user account database for information, so the
1565                 specifiers only work as shortcuts for things which are
1566                 already specified in a different way in the unit
1567                 file. They are fully functional when systemd is
1568                 running in <option>--user</option> mode.</para>
1569         </refsect1>
1570
1571         <refsect1>
1572                 <title>See Also</title>
1573                 <para>
1574                         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1575                         <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1576                         <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1577                         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1578                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1579                         <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1580                         <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1581                         <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1582                         <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1583                         <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1584                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1585                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1586                         <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1587                         <citerefentry><refentrytitle>systemd.scope</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1588                         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1589                         <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1590                         <citerefentry><refentrytitle>systemd-verify</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1591                         <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1592                         <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1593                         <citerefentry><refentrytitle>uname</refentrytitle><manvolnum>1</manvolnum></citerefentry>
1594                 </para>
1595         </refsect1>
1596
1597 </refentry>