man/systemd.unit.xml

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