man/systemd.special.xml

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   2 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
   3   "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
   4 <!-- SPDX-License-Identifier: LGPL-2.1+ -->
   5
   6 <refentry id="systemd.special">
   7
   8   <refentryinfo>
   9     <title>systemd.special</title>
  10     <productname>systemd</productname>
  11   </refentryinfo>
  12
  13   <refmeta>
  14     <refentrytitle>systemd.special</refentrytitle>
  15     <manvolnum>7</manvolnum>
  16   </refmeta>
  17
  18   <refnamediv>
  19     <refname>systemd.special</refname>
  20     <refpurpose>Special systemd units</refpurpose>
  21   </refnamediv>
  22
  23   <refsynopsisdiv><para>
  24     <!-- sort alphabetically, targets first --><filename>basic.target</filename>,
  25     <filename>bluetooth.target</filename>,
  26     <filename>cryptsetup-pre.target</filename>,
  27     <filename>cryptsetup.target</filename>,
  28     <filename>ctrl-alt-del.target</filename>,
  29     <filename>blockdev@.target</filename>,
  30     <filename>boot-complete.target</filename>,
  31     <filename>default.target</filename>,
  32     <filename>emergency.target</filename>,
  33     <filename>exit.target</filename>,
  34     <filename>final.target</filename>,
  35     <filename>getty.target</filename>,
  36     <filename>getty-pre.target</filename>,
  37     <filename>graphical.target</filename>,
  38     <filename>halt.target</filename>,
  39     <filename>hibernate.target</filename>,
  40     <filename>hybrid-sleep.target</filename>,
  41     <filename>suspend-then-hibernate.target</filename>,
  42     <filename>initrd.target</filename>,
  43     <filename>initrd-fs.target</filename>,
  44     <filename>initrd-root-device.target</filename>,
  45     <filename>initrd-root-fs.target</filename>,
  46     <filename>kbrequest.target</filename>,
  47     <filename>kexec.target</filename>,
  48     <filename>local-fs-pre.target</filename>,
  49     <filename>local-fs.target</filename>,
  50     <filename>machines.target</filename>
  51     <filename>multi-user.target</filename>,
  52     <filename>network-online.target</filename>,
  53     <filename>network-pre.target</filename>,
  54     <filename>network.target</filename>,
  55     <filename>nss-lookup.target</filename>,
  56     <filename>nss-user-lookup.target</filename>,
  57     <filename>paths.target</filename>,
  58     <filename>poweroff.target</filename>,
  59     <filename>printer.target</filename>,
  60     <filename>reboot.target</filename>,
  61     <filename>remote-cryptsetup.target</filename>,
  62     <filename>remote-fs-pre.target</filename>,
  63     <filename>remote-fs.target</filename>,
  64     <filename>rescue.target</filename>,
  65     <filename>rpcbind.target</filename>,
  66     <filename>runlevel2.target</filename>,
  67     <filename>runlevel3.target</filename>,
  68     <filename>runlevel4.target</filename>,
  69     <filename>runlevel5.target</filename>,
  70     <filename>shutdown.target</filename>,
  71     <filename>sigpwr.target</filename>,
  72     <filename>sleep.target</filename>,
  73     <filename>slices.target</filename>,
  74     <filename>smartcard.target</filename>,
  75     <filename>sockets.target</filename>,
  76     <filename>sound.target</filename>,
  77     <filename>suspend.target</filename>,
  78     <filename>swap.target</filename>,
  79     <filename>sysinit.target</filename>,
  80     <filename>system-update.target</filename>,
  81     <filename>system-update-pre.target</filename>,
  82     <filename>time-set.target</filename>,
  83     <filename>time-sync.target</filename>,
  84     <filename>timers.target</filename>,
  85     <filename>umount.target</filename>,
  86     <filename>usb-gadget.target</filename>,
  87     <!-- slices --><filename>-.slice</filename>,
  88     <filename>system.slice</filename>,
  89     <filename>user.slice</filename>,
  90     <filename>machine.slice</filename>,
  91     <!-- the rest --><filename>-.mount</filename>,
  92     <filename>dbus.service</filename>,
  93     <filename>dbus.socket</filename>,
  94     <filename>display-manager.service</filename>,
  95     <filename>init.scope</filename>,
  96     <filename>syslog.socket</filename>,
  97     <filename>system-update-cleanup.service</filename>
  98   </para></refsynopsisdiv>
  99
 100   <refsect1>
 101     <title>Description</title>
 102
 103     <para>A few units are treated specially by systemd. Many of them have
 104     special internal semantics and cannot be renamed, while others simply
 105     have a standard meaning and should be present on all systems.</para>
 106   </refsect1>
 107
 108   <refsect1>
 109     <title>Units managed by the system service manager</title>
 110
 111     <refsect2>
 112       <title>Special System Units</title>
 113
 114       <variablelist>
 115         <varlistentry>
 116           <term><filename>-.mount</filename></term>
 117           <listitem>
 118             <para>The root mount point, i.e. the mount unit for the <filename>/</filename>
 119             path. This unit is unconditionally active, during the entire time the system is up, as
 120             this mount point is where the basic userspace is running from.</para>
 121           </listitem>
 122         </varlistentry>
 123
 124         <varlistentry>
 125           <term><filename>basic.target</filename></term>
 126           <listitem>
 127             <para>A special target unit covering basic boot-up.</para>
 128
 129             <para>systemd automatically adds dependency of the type
 130             <varname>After=</varname> for this target unit to all
 131             services (except for those with
 132             <varname>DefaultDependencies=no</varname>).</para>
 133
 134             <para>Usually, this should pull-in all local mount points plus
 135             <filename>/var</filename>, <filename>/tmp</filename> and
 136             <filename>/var/tmp</filename>, swap devices, sockets, timers,
 137             path units and other basic initialization necessary for general
 138             purpose daemons. The mentioned mount points are special cased
 139             to allow them to be remote.
 140             </para>
 141
 142             <para>This target usually does not pull in any non-target units
 143             directly, but rather does so indirectly via other early boot targets.
 144             It is instead meant as a synchronization point for late boot
 145             services. Refer to
 146             <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>
 147             for details on the targets involved.
 148             </para>
 149           </listitem>
 150         </varlistentry>
 151         <varlistentry>
 152           <term><filename>boot-complete.target</filename></term>
 153           <listitem>
 154             <para>This target is intended as generic synchronization point for services that shall determine or act on
 155             whether the boot process completed successfully. Order units that are required to succeed for a boot process
 156             to be considered successful before this unit, and add a <varname>Requires=</varname> dependency from the
 157             target unit to them. Order units that shall only run when the boot process is considered successful after the
 158             target unit and pull in the target from it, also with <varname>Requires=</varname>. Note that by default this
 159             target unit is not part of the initial boot transaction, but is supposed to be pulled in only if required by
 160             units that want to run only on successful boots.</para>
 161
 162             <para>See
 163             <citerefentry><refentrytitle>systemd-boot-check-no-failures.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 164             for a service that implements a generic system health check and orders itself before
 165             <filename>boot-complete.target</filename>.</para>
 166
 167             <para>See
 168             <citerefentry><refentrytitle>systemd-bless-boot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 169             for a service that propagates boot success information to the boot loader, and orders itself after
 170             <filename>boot-complete.target</filename>.</para>
 171           </listitem>
 172         </varlistentry>
 173         <varlistentry>
 174           <term><filename>ctrl-alt-del.target</filename></term>
 175           <listitem>
 176             <para>systemd starts this target whenever Control+Alt+Del is
 177             pressed on the console. Usually, this should be aliased
 178             (symlinked) to <filename>reboot.target</filename>.</para>
 179           </listitem>
 180         </varlistentry>
 181         <varlistentry>
 182           <term><filename>cryptsetup.target</filename></term>
 183           <listitem>
 184             <para>A target that pulls in setup services for all
 185             encrypted block devices.</para>
 186           </listitem>
 187         </varlistentry>
 188         <varlistentry>
 189           <term><filename>dbus.service</filename></term>
 190           <listitem>
 191             <para>A special unit for the D-Bus bus daemon. As soon as
 192             this service is fully started up systemd will connect to it
 193             and register its service.</para>
 194           </listitem>
 195         </varlistentry>
 196         <varlistentry>
 197           <term><filename>dbus.socket</filename></term>
 198           <listitem>
 199             <para>A special unit for the D-Bus system bus socket. All
 200             units with <varname>Type=dbus</varname> automatically gain a
 201             dependency on this unit.</para>
 202           </listitem>
 203         </varlistentry>
 204         <varlistentry>
 205           <term><filename>default.target</filename></term>
 206           <listitem>
 207             <para>The default unit systemd starts at bootup. Usually, this should be aliased (symlinked) to
 208             <filename>multi-user.target</filename> or <filename>graphical.target</filename>. See
 209             <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
 210             more discussion.</para>
 211
 212             <para>The default unit systemd starts at bootup can be overridden with the
 213             <varname>systemd.unit=</varname> kernel command line option, or more conveniently, with the short
 214             names like <varname>single</varname>, <varname>rescue</varname>, <varname>1</varname>,
 215             <varname>3</varname>, <varname>5</varname>, …; see
 216             <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
 217           </listitem>
 218         </varlistentry>
 219         <varlistentry>
 220           <term><filename>display-manager.service</filename></term>
 221           <listitem>
 222             <para>The display manager service. Usually, this should be
 223             aliased (symlinked) to <filename>gdm.service</filename> or a
 224             similar display manager service.</para>
 225           </listitem>
 226         </varlistentry>
 227         <varlistentry>
 228           <term><filename>emergency.target</filename></term>
 229           <listitem>
 230             <para>A special target unit that starts an emergency shell on the main console. This
 231             target does not pull in other services or mounts. It is the most minimal version of
 232             starting the system in order to acquire an interactive shell; the only processes running
 233             are usually just the system manager (PID 1) and the shell process. This unit may be used
 234             by specifying <varname>emergency</varname> on the kernel command line; it is
 235             also used when a file system check on a required file system fails and boot-up cannot
 236             continue. Compare with <filename>rescue.target</filename>, which serves a similar
 237             purpose, but also starts the most basic services and mounts all file systems.</para>
 238
 239             <para>In many ways booting into <filename>emergency.target</filename> is similar to the
 240             effect of booting with <literal>init=/bin/sh</literal> on the kernel command line,
 241             except that emergency mode provides you with the full system and service manager, and
 242             allows starting individual units in order to continue the boot process in steps.</para>
 243
 244             <para>Note that depending on how <filename>emergency.target</filename> is reached, the root file
 245             system might be mounted read-only or read-write (no remounting is done specially for this
 246             target). For example, the system may boot with root mounted read-only when <varname>ro</varname>
 247             is used on the kernel command line and remain this way for <filename>emergency.target</filename>,
 248             or the system may transition to <filename>emergency.target</filename> after the system has been
 249             partially booted and disks have already been remounted read-write.</para>
 250           </listitem>
 251         </varlistentry>
 252         <varlistentry>
 253           <term><filename>exit.target</filename></term>
 254           <listitem>
 255             <para>A special service unit for shutting down the system or
 256             user service manager. It is equivalent to
 257             <filename>poweroff.target</filename> on non-container
 258             systems, and also works in containers.</para>
 259
 260             <para>systemd will start this unit when it receives the
 261             <constant>SIGTERM</constant> or <constant>SIGINT</constant>
 262             signal when running as user service daemon.</para>
 263
 264             <para>Normally, this (indirectly) pulls in
 265             <filename>shutdown.target</filename>, which in turn should be
 266             conflicted by all units that want to be scheduled for
 267             shutdown when the service manager starts to exit.</para>
 268           </listitem>
 269         </varlistentry>
 270         <varlistentry>
 271           <term><filename>final.target</filename></term>
 272           <listitem>
 273             <para>A special target unit that is used during the shutdown
 274             logic and may be used to pull in late services after all
 275             normal services are already terminated and all mounts
 276             unmounted.
 277             </para>
 278           </listitem>
 279         </varlistentry>
 280         <varlistentry>
 281           <term><filename>getty.target</filename></term>
 282           <listitem>
 283             <para>A special target unit that pulls in statically
 284             configured local TTY <filename>getty</filename> instances.
 285             </para>
 286           </listitem>
 287         </varlistentry>
 288         <varlistentry>
 289           <term><filename>graphical.target</filename></term>
 290           <listitem>
 291             <para>A special target unit for setting up a graphical login
 292             screen. This pulls in
 293             <filename>multi-user.target</filename>.</para>
 294
 295             <para>Units that are needed for graphical logins shall add
 296             <varname>Wants=</varname> dependencies for their unit to
 297             this unit (or <filename>multi-user.target</filename>) during
 298             installation. This is best configured via
 299             <varname>WantedBy=graphical.target</varname> in the unit's
 300             [Install] section.</para>
 301           </listitem>
 302         </varlistentry>
 303         <varlistentry>
 304           <term><filename>hibernate.target</filename></term>
 305           <listitem>
 306             <para>A special target unit for hibernating the system. This
 307             pulls in <filename>sleep.target</filename>.</para>
 308           </listitem>
 309         </varlistentry>
 310         <varlistentry>
 311           <term><filename>hybrid-sleep.target</filename></term>
 312           <listitem>
 313             <para>A special target unit for hibernating and suspending
 314             the system at the same time. This pulls in
 315             <filename>sleep.target</filename>.</para>
 316           </listitem>
 317         </varlistentry>
 318         <varlistentry>
 319           <term><filename>suspend-then-hibernate.target</filename></term>
 320           <listitem>
 321             <para>A special target unit for suspending the system for a period
 322             of time, waking it and putting it into hibernate. This pulls in
 323             <filename>sleep.target</filename>.</para>
 324           </listitem>
 325         </varlistentry>
 326
 327         <varlistentry>
 328           <term><filename>halt.target</filename></term>
 329           <listitem>
 330             <para>A special target unit for shutting down and halting
 331             the system. Note that this target is distinct from
 332             <filename>poweroff.target</filename> in that it generally
 333             really just halts the system rather than powering it
 334             down.</para>
 335
 336             <para>Applications wanting to halt the system should not start this unit
 337             directly, but should instead execute <command>systemctl halt</command>
 338             (possibly with the <option>--no-block</option> option) or call
 339             <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 340             <command>org.freedesktop.systemd1.Manager.Halt</command> D-Bus method
 341             directly.</para>
 342           </listitem>
 343         </varlistentry>
 344         <varlistentry>
 345           <term><filename>init.scope</filename></term>
 346           <listitem>
 347             <para>This scope unit is where the system and service manager (PID 1) itself resides. It
 348             is active as long as the system is running.</para>
 349           </listitem>
 350         </varlistentry>
 351         <varlistentry>
 352           <term><filename>initrd.target</filename></term>
 353           <listitem>
 354             <para>This is the default target in the initramfs, similar to <filename>default.target</filename>
 355             in the main system. It is used to mount the real root and transition to it. See
 356             <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
 357             more discussion.</para>
 358           </listitem>
 359         </varlistentry>
 360         <varlistentry>
 361           <term><filename>initrd-fs.target</filename></term>
 362           <listitem>
 363             <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 364             automatically adds dependencies of type
 365             <varname>Before=</varname> to
 366             <filename>sysroot-usr.mount</filename> and all mount points
 367             found in <filename>/etc/fstab</filename> that have
 368             <option>x-initrd.mount</option> and not have
 369             <option>noauto</option> mount options set.</para>
 370           </listitem>
 371         </varlistentry>
 372         <varlistentry>
 373           <term><filename>initrd-root-device.target</filename></term>
 374           <listitem>
 375             <para>A special initrd target unit that is reached when the root filesystem device is available, but before
 376             it has been mounted.
 377             <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 378             and
 379             <citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 380             automatically setup the appropriate dependencies to make this happen.
 381             </para>
 382           </listitem>
 383         </varlistentry>
 384         <varlistentry>
 385           <term><filename>initrd-root-fs.target</filename></term>
 386           <listitem>
 387             <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 388             automatically adds dependencies of type
 389             <varname>Before=</varname> to the
 390             <filename>sysroot.mount</filename> unit, which is generated
 391             from the kernel command line.
 392             </para>
 393           </listitem>
 394         </varlistentry>
 395         <varlistentry>
 396           <term><filename>kbrequest.target</filename></term>
 397           <listitem>
 398             <para>systemd starts this target whenever Alt+ArrowUp is
 399             pressed on the console. Note that any user with physical access
 400             to the machine will be able to do this, without authentication,
 401             so this should be used carefully.</para>
 402           </listitem>
 403         </varlistentry>
 404         <varlistentry>
 405           <term><filename>kexec.target</filename></term>
 406           <listitem>
 407             <para>A special target unit for shutting down and rebooting
 408             the system via kexec.</para>
 409
 410             <para>Applications wanting to reboot the system should not start this unit
 411             directly, but should instead execute <command>systemctl kexec</command>
 412             (possibly with the <option>--no-block</option> option) or call
 413             <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
 414             <command>org.freedesktop.systemd1.Manager.KExec</command> D-Bus method
 415             directly.</para>
 416           </listitem>
 417         </varlistentry>
 418         <varlistentry>
 419           <term><filename>local-fs.target</filename></term>
 420           <listitem>
 421             <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
 422             automatically adds dependencies of type
 423             <varname>Before=</varname> to all mount units that refer to
 424             local mount points for this target unit. In addition, it
 425             adds dependencies of type <varname>Wants=</varname> to this
 426             target unit for those mounts listed in
 427             <filename>/etc/fstab</filename> that have the
 428             <option>auto</option> mount option set.</para>
 429           </listitem>
 430         </varlistentry>
 431         <varlistentry>
 432           <term><filename>machines.target</filename></term>
 433           <listitem>
 434             <para>A standard target unit for starting all the containers
 435             and other virtual machines. See <filename>systemd-nspawn@.service</filename>
 436             for an example.</para>
 437           </listitem>
 438         </varlistentry>
 439         <varlistentry>
 440           <term><filename>multi-user.target</filename></term>
 441           <listitem>
 442             <para>A special target unit for setting up a multi-user
 443             system (non-graphical). This is pulled in by
 444             <filename>graphical.target</filename>.</para>
 445
 446             <para>Units that are needed for a multi-user system shall
 447             add <varname>Wants=</varname> dependencies for their unit to
 448             this unit during installation. This is best configured via
 449             <varname>WantedBy=multi-user.target</varname> in the unit's
 450             [Install] section.</para>
 451           </listitem>
 452         </varlistentry>
 453         <varlistentry>
 454           <term><filename>network-online.target</filename></term>
 455           <listitem>
 456             <para>Units that strictly require a configured network
 457             connection should pull in
 458             <filename>network-online.target</filename> (via a
 459             <varname>Wants=</varname> type dependency) and order
 460             themselves after it. This target unit is intended to pull in
 461             a service that delays further execution until the network is
 462             sufficiently set up. What precisely this requires is left to
 463             the implementation of the network managing service.</para>
 464
 465             <para>Note the distinction between this unit and
 466             <filename>network.target</filename>. This unit is an active
 467             unit (i.e. pulled in by the consumer rather than the
 468             provider of this functionality) and pulls in a service which
 469             possibly adds substantial delays to further execution. In
 470             contrast, <filename>network.target</filename> is a passive
 471             unit (i.e. pulled in by the provider of the functionality,
 472             rather than the consumer) that usually does not delay
 473             execution much. Usually, <filename>network.target</filename>
 474             is part of the boot of most systems, while
 475             <filename>network-online.target</filename> is not, except
 476             when at least one unit requires it. Also see <ulink
 477             url="https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
 478             Services After the Network is up</ulink> for more
 479             information.</para>
 480
 481             <para>All mount units for remote network file systems
 482             automatically pull in this unit, and order themselves after
 483             it. Note that networking daemons that simply provide
 484             functionality to other hosts generally do not need to pull
 485             this in.</para>
 486
 487             <para>systemd automatically adds dependencies of type <varname>Wants=</varname> and
 488             <varname>After=</varname> for this target unit to all SysV init script service units
 489             with an LSB header referring to the <literal>$network</literal> facility.</para>
 490
 491             <para>Note that this unit is only useful during the original system start-up
 492             logic. After the system has completed booting up, it will not track the online state of
 493             the system anymore. Due to this it cannot be used as a network connection monitor
 494             concept, it is purely a one-time system start-up concept.</para>
 495             </listitem>
 496         </varlistentry>
 497         <varlistentry>
 498           <term><filename>paths.target</filename></term>
 499           <listitem>
 500             <para>A special target unit that sets up all path units (see
 501             <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 502             for details) that shall be active after boot.</para>
 503
 504             <para>It is recommended that path units installed by
 505             applications get pulled in via <varname>Wants=</varname>
 506             dependencies from this unit. This is best configured via a
 507             <varname>WantedBy=paths.target</varname> in the path unit's
 508             [Install] section.</para>
 509           </listitem>
 510         </varlistentry>
 511         <varlistentry>
 512           <term><filename>poweroff.target</filename></term>
 513           <listitem>
 514             <para>A special target unit for shutting down and powering
 515             off the system.</para>
 516
 517             <para>Applications wanting to power off the system should not start this unit
 518             directly, but should instead execute <command>systemctl poweroff</command>
 519             (possibly with the <option>--no-block</option> option) or call
 520             <citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
 521             <command>org.freedesktop.login1.Manager.PowerOff</command> D-Bus method
 522             directly.</para>
 523
 524             <para><filename>runlevel0.target</filename> is an alias for
 525             this target unit, for compatibility with SysV.</para>
 526           </listitem>
 527         </varlistentry>
 528         <varlistentry>
 529           <term><filename>reboot.target</filename></term>
 530           <listitem>
 531             <para>A special target unit for shutting down and rebooting
 532             the system.</para>
 533
 534             <para>Applications wanting to reboot the system should not start this unit
 535             directly, but should instead execute <command>systemctl reboot</command>
 536             (possibly with the <option>--no-block</option> option) or call
 537             <citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
 538             <command>org.freedesktop.login1.Manager.Reboot</command> D-Bus method
 539             directly.</para>
 540
 541             <para><filename>runlevel6.target</filename> is an alias for
 542             this target unit, for compatibility with SysV.</para>
 543           </listitem>
 544         </varlistentry>
 545         <varlistentry>
 546           <term><filename>remote-cryptsetup.target</filename></term>
 547           <listitem>
 548             <para>Similar to <filename>cryptsetup.target</filename>, but for encrypted
 549             devices which are accessed over the network. It is used for
 550             <citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 551             entries marked with <option>_netdev</option>.</para>
 552           </listitem>
 553         </varlistentry>
 554         <varlistentry>
 555           <term><filename>remote-fs.target</filename></term>
 556           <listitem>
 557             <para>Similar to <filename>local-fs.target</filename>, but
 558             for remote mount points.</para>
 559
 560             <para>systemd automatically adds dependencies of type
 561             <varname>After=</varname> for this target unit to all SysV
 562             init script service units with an LSB header referring to
 563             the <literal>$remote_fs</literal> facility.</para>
 564           </listitem>
 565         </varlistentry>
 566         <varlistentry>
 567           <term><filename>rescue.target</filename></term>
 568           <listitem>
 569             <para>A special target unit that pulls in the base system (including system mounts) and
 570             spawns a rescue shell. Isolate to this target in order to administer the system in
 571             single-user mode with all file systems mounted but with no services running, except for
 572             the most basic. Compare with <filename>emergency.target</filename>, which is much more
 573             reduced and does not provide the file systems or most basic services. Compare with
 574             <filename>multi-user.target</filename>, this target could be seen as
 575             <filename>single-user.target</filename>.</para>
 576
 577             <para><filename>runlevel1.target</filename> is an alias for this target unit, for
 578             compatibility with SysV.</para>
 579
 580             <para>Use the <literal>systemd.unit=rescue.target</literal> kernel command line option
 581             to boot into this mode. A short alias for this kernel command line option is
 582             <literal>1</literal>, for compatibility with SysV.</para>
 583           </listitem>
 584         </varlistentry>
 585         <varlistentry>
 586           <term><filename>runlevel2.target</filename></term>
 587           <term><filename>runlevel3.target</filename></term>
 588           <term><filename>runlevel4.target</filename></term>
 589           <term><filename>runlevel5.target</filename></term>
 590           <listitem>
 591             <para>These are targets that are called whenever the SysV
 592             compatibility code asks for runlevel 2, 3, 4, 5,
 593             respectively. It is a good idea to make this an alias for
 594             (i.e. symlink to) <filename>graphical.target</filename>
 595             (for runlevel 5) or <filename>multi-user.target</filename>
 596             (the others).</para>
 597           </listitem>
 598         </varlistentry>
 599         <varlistentry>
 600           <term><filename>shutdown.target</filename></term>
 601           <listitem>
 602             <para>A special target unit that terminates the services on
 603             system shutdown.</para>
 604
 605             <para>Services that shall be terminated on system shutdown
 606             shall add <varname>Conflicts=</varname> and
 607             <varname>Before=</varname> dependencies to this unit for
 608             their service unit, which is implicitly done when
 609             <varname>DefaultDependencies=yes</varname> is set (the
 610             default).</para>
 611           </listitem>
 612         </varlistentry>
 613         <varlistentry>
 614           <term><filename>sigpwr.target</filename></term>
 615           <listitem>
 616             <para>A special target that is started when systemd receives
 617             the SIGPWR process signal, which is normally sent by the
 618             kernel or UPS daemons when power fails.</para>
 619           </listitem>
 620         </varlistentry>
 621         <varlistentry>
 622           <term><filename>sleep.target</filename></term>
 623           <listitem>
 624             <para>A special target unit that is pulled in by
 625             <filename>suspend.target</filename>,
 626             <filename>hibernate.target</filename> and
 627             <filename>hybrid-sleep.target</filename> and may be used to
 628             hook units into the sleep state logic.</para>
 629           </listitem>
 630         </varlistentry>
 631         <varlistentry>
 632           <term><filename>slices.target</filename></term>
 633           <listitem>
 634             <para>A special target unit that sets up all slice units (see
 635             <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 636             for details) that shall always be active after boot. By default the generic
 637             <filename>system.slice</filename> slice unit as well as the root slice unit
 638             <filename>-.slice</filename> are pulled in and ordered before this unit (see
 639             below).</para>
 640
 641             <para>Adding slice units to <filename>slices.target</filename> is generally not
 642             necessary. Instead, when some unit that uses <varname>Slice=</varname> is started, the
 643             specified slice will be started automatically. Adding
 644             <varname>WantedBy=slices.target</varname> lines to the [Install]
 645             section should only be done for units that need to be always active. In that case care
 646             needs to be taken to avoid creating a loop through the automatic dependencies on
 647             "parent" slices.</para>
 648           </listitem>
 649         </varlistentry>
 650         <varlistentry>
 651           <term><filename>sockets.target</filename></term>
 652           <listitem>
 653             <para>A special target unit that sets up all socket
 654             units (see
 655             <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 656             for details) that shall be active after boot.</para>
 657
 658             <para>Services that can be socket-activated shall add
 659             <varname>Wants=</varname> dependencies to this unit for
 660             their socket unit during installation. This is best
 661             configured via a <varname>WantedBy=sockets.target</varname>
 662             in the socket unit's [Install]
 663             section.</para>
 664           </listitem>
 665         </varlistentry>
 666         <varlistentry>
 667           <term><filename>suspend.target</filename></term>
 668           <listitem>
 669             <para>A special target unit for suspending the system. This
 670             pulls in <filename>sleep.target</filename>.</para>
 671           </listitem>
 672         </varlistentry>
 673         <varlistentry>
 674           <term><filename>swap.target</filename></term>
 675           <listitem>
 676             <para>Similar to <filename>local-fs.target</filename>, but
 677             for swap partitions and swap files.</para>
 678           </listitem>
 679         </varlistentry>
 680         <varlistentry>
 681           <term><filename>sysinit.target</filename></term>
 682           <listitem>
 683             <para>systemd automatically adds dependencies of the types
 684             <varname>Requires=</varname> and <varname>After=</varname>
 685             for this target unit to all services (except for those with
 686             <varname>DefaultDependencies=no</varname>).</para>
 687
 688             <para>This target pulls in the services required for system
 689             initialization. System services pulled in by this target should
 690             declare <varname>DefaultDependencies=no</varname> and specify
 691             all their dependencies manually, including access to anything
 692             more than a read only root filesystem. For details on the
 693             dependencies of this target, refer to
 694             <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
 695             </para>
 696           </listitem>
 697         </varlistentry>
 698         <varlistentry>
 699           <term><filename>syslog.socket</filename></term>
 700           <listitem>
 701             <para>The socket unit syslog implementations should listen
 702             on. All userspace log messages will be made available on
 703             this socket. For more information about syslog integration,
 704             please consult the <ulink
 705             url="https://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog
 706             Interface</ulink> document.</para>
 707           </listitem>
 708         </varlistentry>
 709         <varlistentry>
 710           <term><filename>system-update.target</filename></term>
 711           <term><filename>system-update-pre.target</filename></term>
 712           <term><filename>system-update-cleanup.service</filename></term>
 713           <listitem>
 714             <para>A special target unit that is used for offline system updates.
 715             <citerefentry><refentrytitle>systemd-system-update-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
 716             will redirect the boot process to this target if <filename>/system-update</filename>
 717             exists. For more information see
 718             <citerefentry><refentrytitle>systemd.offline-updates</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
 719             </para>
 720
 721             <para>Updates should happen before the <filename>system-update.target</filename> is
 722             reached, and the services which implement them should cause the machine to reboot. The
 723             main units executing the update should order themselves after
 724             <filename>system-update-pre.target</filename> but not pull it in. Services which want to
 725             run during system updates only, but before the actual system update is executed should
 726             order themselves before this unit and pull it in. As a safety measure, if this does not
 727             happen, and <filename>/system-update</filename> still exists after
 728             <filename>system-update.target</filename> is reached,
 729             <filename>system-update-cleanup.service</filename> will remove this symlink and reboot
 730             the machine.</para>
 731           </listitem>
 732         </varlistentry>
 733         <varlistentry>
 734           <term><filename>timers.target</filename></term>
 735           <listitem>
 736             <para>A special target unit that sets up all timer units
 737             (see
 738             <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>
 739             for details) that shall be active after boot.</para>
 740
 741             <para>It is recommended that timer units installed by
 742             applications get pulled in via <varname>Wants=</varname>
 743             dependencies from this unit. This is best configured via
 744             <varname>WantedBy=timers.target</varname> in the timer
 745             unit's [Install] section.</para>
 746           </listitem>
 747         </varlistentry>
 748         <varlistentry>
 749           <term><filename>umount.target</filename></term>
 750           <listitem>
 751             <para>A special target unit that unmounts all mount and
 752             automount points on system shutdown.</para>
 753
 754             <para>Mounts that shall be unmounted on system shutdown
 755             shall add Conflicts dependencies to this unit for their
 756             mount unit, which is implicitly done when
 757             <varname>DefaultDependencies=yes</varname> is set (the
 758             default).</para>
 759           </listitem>
 760         </varlistentry>
 761
 762       </variablelist>
 763     </refsect2>
 764
 765     <refsect2>
 766       <title>Special System Units for Devices</title>
 767
 768       <para>Some target units are automatically pulled in as devices of
 769       certain kinds show up in the system. These may be used to
 770       automatically activate various services based on the specific type
 771       of the available hardware.</para>
 772
 773       <variablelist>
 774         <varlistentry>
 775           <term><filename>bluetooth.target</filename></term>
 776           <listitem>
 777             <para>This target is started automatically as soon as a
 778             Bluetooth controller is plugged in or becomes available at
 779             boot.</para>
 780
 781             <para>This may be used to pull in Bluetooth management
 782             daemons dynamically when Bluetooth hardware is found.</para>
 783           </listitem>
 784         </varlistentry>
 785         <varlistentry>
 786           <term><filename>printer.target</filename></term>
 787           <listitem>
 788             <para>This target is started automatically as soon as a
 789             printer is plugged in or becomes available at boot.</para>
 790
 791             <para>This may be used to pull in printer management daemons
 792             dynamically when printer hardware is found.</para>
 793           </listitem>
 794         </varlistentry>
 795         <varlistentry>
 796           <term><filename>smartcard.target</filename></term>
 797           <listitem>
 798             <para>This target is started automatically as soon as a
 799             smartcard controller is plugged in or becomes available at
 800             boot.</para>
 801
 802             <para>This may be used to pull in smartcard management
 803             daemons dynamically when smartcard hardware is found.</para>
 804           </listitem>
 805         </varlistentry>
 806         <varlistentry>
 807           <term><filename>sound.target</filename></term>
 808           <listitem>
 809             <para>This target is started automatically as soon as a
 810             sound card is plugged in or becomes available at
 811             boot.</para>
 812
 813             <para>This may be used to pull in audio management daemons
 814             dynamically when audio hardware is found.</para>
 815           </listitem>
 816         </varlistentry>
 817         <varlistentry>
 818           <term><filename>usb-gadget.target</filename></term>
 819           <listitem>
 820             <para>This target is started automatically as soon as a
 821             USB Device Controller becomes available at boot.</para>
 822
 823             <para>This may be used to pull in usb gadget
 824             dynamically when UDC hardware is found.</para>
 825           </listitem>
 826         </varlistentry>
 827       </variablelist>
 828     </refsect2>
 829
 830     <refsect2>
 831       <title>Special Passive System Units </title>
 832
 833       <para>A number of special system targets are defined that can be
 834       used to properly order boot-up of optional services. These targets
 835       are generally not part of the initial boot transaction, unless
 836       they are explicitly pulled in by one of the implementing services.
 837       Note specifically that these <emphasis>passive</emphasis> target
 838       units are generally not pulled in by the consumer of a service,
 839       but by the provider of the service. This means: a consuming
 840       service should order itself after these targets (as appropriate),
 841       but not pull it in. A providing service should order itself before
 842       these targets (as appropriate) and pull it in (via a
 843       <varname>Wants=</varname> type dependency).</para>
 844
 845       <para>Note that these passive units cannot be started manually,
 846       i.e. <literal>systemctl start time-sync.target</literal> will fail
 847       with an error. They can only be pulled in by dependency. This is
 848       enforced since they exist for ordering purposes only and thus are
 849       not useful as only unit within a transaction.</para>
 850
 851       <variablelist>
 852         <varlistentry>
 853           <term><filename>blockdev@.target</filename></term>
 854           <listitem><para>This template unit is used to order mount units and other consumers of block
 855           devices after services that synthesize these block devices. In particular, this is intended to be
 856           used with storage services (such as
 857           <citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
 858           that allocate and manage a virtual block device. Storage services are ordered before an instance of
 859           <filename>blockdev@.target</filename>, and the consumer units after it. The ordering is
 860           particularly relevant during shutdown, as it ensures that the mount is deactivated first and the
 861           service backing the mount later. The <filename>blockdev@.target</filename> instance should be
 862           pulled in via a <option>Wants=</option> dependency of the storage daemon and thus generally not be
 863           part of any transaction unless a storage daemon is used. The instance name for instances of this
 864           template unit must be a properly escaped block device node path, e.g.
 865           <filename>blockdev@dev-mapper-foobar.target</filename> for the storage device
 866           <filename>/dev/mapper/foobar</filename>.</para></listitem>
 867         </varlistentry>
 868         <varlistentry>
 869           <term><filename>cryptsetup-pre.target</filename></term>
 870           <listitem>
 871             <para>This passive target unit may be pulled in by services
 872             that want to run before any encrypted block device is set
 873             up. All encrypted block devices are set up after this target
 874             has been reached. Since the shutdown order is implicitly the
 875             reverse start-up order between units, this target is
 876             particularly useful to ensure that a service is shut down
 877             only after all encrypted block devices are fully
 878             stopped.</para>
 879           </listitem>
 880         </varlistentry>
 881         <varlistentry>
 882           <term><filename>getty-pre.target</filename></term>
 883           <listitem>
 884             <para>A special passive target unit. Users of this target
 885             are expected to pull it in the boot transaction via
 886             a dependency (e.g. <varname>Wants=</varname>). Order your
 887             unit before this unit if you want to make use of the console
 888             just before <filename>getty</filename> is started.
 889             </para>
 890           </listitem>
 891         </varlistentry>
 892         <varlistentry>
 893           <term><filename>local-fs-pre.target</filename></term>
 894           <listitem>
 895             <para>This target unit is
 896             automatically ordered before
 897             all local mount points marked
 898             with <option>auto</option>
 899             (see above). It can be used to
 900             execute certain units before
 901             all local mounts.</para>
 902           </listitem>
 903         </varlistentry>
 904         <varlistentry>
 905           <term><filename>network.target</filename></term>
 906           <listitem>
 907             <para>This unit is supposed to indicate when network
 908             functionality is available, but it is only very weakly
 909             defined what that is supposed to mean, with one exception:
 910             at shutdown, a unit that is ordered after
 911             <filename>network.target</filename> will be stopped before
 912             the network — to whatever level it might be set up then —
 913             is shut down. It is hence useful when writing service files
 914             that require network access on shutdown, which should order
 915             themselves after this target, but not pull it in. Also see
 916             <ulink url="https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
 917             Services After the Network is up</ulink> for more
 918             information. Also see
 919             <filename>network-online.target</filename> described
 920             above.</para>
 921           </listitem>
 922         </varlistentry>
 923         <varlistentry>
 924           <term><filename>network-pre.target</filename></term>
 925           <listitem>
 926             <para>This passive target unit may be pulled in by services
 927             that want to run before any network is set up, for example
 928             for the purpose of setting up a firewall. All network
 929             management software orders itself after this target, but
 930             does not pull it in.</para>
 931           </listitem>
 932         </varlistentry>
 933         <varlistentry>
 934           <term><filename>nss-lookup.target</filename></term>
 935           <listitem>
 936             <para>A target that should be used as synchronization point for all host/network name
 937             service lookups. Note that this is independent of UNIX user/group name lookups for which
 938             <filename>nss-user-lookup.target</filename> should be used.  All services for which the
 939             availability of full host/network name resolution is essential should be ordered after
 940             this target, but not pull it in. systemd automatically adds dependencies of type
 941             <varname>After=</varname> for this target unit to all SysV init script service units
 942             with an LSB header referring to the <literal>$named</literal> facility.</para>
 943           </listitem>
 944         </varlistentry>
 945         <varlistentry>
 946           <term><filename>nss-user-lookup.target</filename></term>
 947           <listitem>
 948             <para>A target that should be used as synchronization point for all regular UNIX
 949             user/group name service lookups. Note that this is independent of host/network name
 950             lookups for which <filename>nss-lookup.target</filename> should be used. All services
 951             for which the availability of the full user/group database is essential should be
 952             ordered after this target, but not pull it in. All services which provide parts of the
 953             user/group database should be ordered before this target, and pull it in. Note that this
 954             unit is only relevant for regular users and groups — system users and groups are
 955             required to be resolvable during earliest boot already, and hence do not need any
 956             special ordering against this target.</para>
 957           </listitem>
 958         </varlistentry>
 959         <varlistentry>
 960           <term><filename>remote-fs-pre.target</filename></term>
 961           <listitem>
 962             <para>This target unit is automatically ordered before all
 963             mount point units (see above) and cryptsetup devices
 964             marked with the <option>_netdev</option>. It can be used to run
 965             certain units before remote encrypted devices and mounts are established.
 966             Note that this unit is generally not part of the initial
 967             transaction, unless the unit that wants to be ordered before
 968             all remote mounts pulls it in via a
 969             <varname>Wants=</varname> type dependency. If the unit wants
 970             to be pulled in by the first remote mount showing up, it
 971             should use <filename>network-online.target</filename> (see
 972             above).</para>
 973           </listitem>
 974         </varlistentry>
 975         <varlistentry>
 976           <term><filename>rpcbind.target</filename></term>
 977           <listitem>
 978             <para>The portmapper/rpcbind pulls in this target and orders
 979             itself before it, to indicate its availability. systemd
 980             automatically adds dependencies of type
 981             <varname>After=</varname> for this target unit to all SysV
 982             init script service units with an LSB header referring to
 983             the <literal>$portmap</literal> facility.</para>
 984           </listitem>
 985         </varlistentry>
 986         <varlistentry>
 987           <term><filename>time-set.target</filename></term>
 988           <listitem>
 989             <para>Services responsible for setting the system clock from
 990             a local source (such as a maintained timestamp file or
 991             imprecise real-time clock) should pull in this target and
 992             order themselves before it.  Services where approximate time
 993             is desired should be ordered after this unit, but not pull
 994             it in.  This target does not provide the accuracy guarantees
 995             of <filename>time-sync.target</filename>.</para>
 996           </listitem>
 997         </varlistentry>
 998         <varlistentry>
 999           <term><filename>time-sync.target</filename></term>
1000           <listitem>
1001             <para>Services responsible for synchronizing the system
1002             clock from a remote source (such as NTP client
1003             implementations) should pull in this target and order
1004             themselves before it. All services where correct time is
1005             essential should be ordered after this unit, but not pull it
1006             in. systemd automatically adds dependencies of type
1007             <varname>After=</varname> for this target unit to all SysV
1008             init script service units with an LSB header referring to
1009             the <literal>$time</literal> facility. </para>
1010           </listitem>
1011         </varlistentry>
1012       </variablelist>
1013     </refsect2>
1014
1015     <refsect2>
1016       <title>Special Slice Units</title>
1017
1018       <para>There are four <literal>.slice</literal> units which form the basis of the hierarchy for
1019       assignment of resources for services, users, and virtual machines or containers. See
1020       <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1021       for details about slice units.</para>
1022
1023       <variablelist>
1024         <varlistentry>
1025           <term><filename>-.slice</filename></term>
1026           <listitem>
1027             <para>The root slice is the root of the slice hierarchy. It usually does not contain
1028             units directly, but may be used to set defaults for the whole tree.</para>
1029           </listitem>
1030         </varlistentry>
1031
1032         <varlistentry>
1033           <term><filename>system.slice</filename></term>
1034           <listitem>
1035             <para>By default, all system services started by
1036             <command>systemd</command> are found in this slice.</para>
1037           </listitem>
1038         </varlistentry>
1039
1040         <varlistentry>
1041           <term><filename>user.slice</filename></term>
1042           <listitem>
1043             <para>By default, all user processes and services started on
1044             behalf of the user, including the per-user systemd instance
1045             are found in this slice.  This is pulled in by
1046             <filename>systemd-logind.service</filename>.</para>
1047           </listitem>
1048         </varlistentry>
1049
1050         <varlistentry>
1051           <term><filename>machine.slice</filename></term>
1052           <listitem>
1053             <para>By default, all virtual machines and containers
1054             registered with <command>systemd-machined</command> are
1055             found in this slice. This is pulled in by
1056             <filename>systemd-machined.service</filename>.</para>
1057           </listitem>
1058         </varlistentry>
1059       </variablelist>
1060     </refsect2>
1061   </refsect1>
1062
1063   <refsect1>
1064     <title>Units managed by the user service manager</title>
1065
1066     <refsect2>
1067       <title>Special User Units</title>
1068
1069       <para>When systemd runs as a user instance, the following special
1070       units are available:</para>
1071
1072       <variablelist>
1073         <varlistentry>
1074           <term><filename>default.target</filename></term>
1075           <listitem>
1076             <para>This is the main target of the user session, started by default. Various services that
1077             compose the normal user session should be pulled into this target. In this regard,
1078             <filename>default.target</filename> is similar to <filename>multi-user.target</filename> in the
1079             system instance, but it is a real unit, not an alias.</para>
1080           </listitem>
1081         </varlistentry>
1082       </variablelist>
1083
1084       <para>In addition, the following units are available which have definitions similar to their
1085       system counterparts:
1086       <filename>exit.target</filename>,
1087       <filename>shutdown.target</filename>,
1088       <filename>sockets.target</filename>,
1089       <filename>timers.target</filename>,
1090       <filename>paths.target</filename>,
1091       <filename>bluetooth.target</filename>,
1092       <filename>printer.target</filename>,
1093       <filename>smartcard.target</filename>,
1094       <filename>sound.target</filename>.</para>
1095     </refsect2>
1096
1097     <refsect2>
1098       <title>Special Passive User Units</title>
1099
1100       <variablelist>
1101         <varlistentry>
1102           <term><filename>graphical-session.target</filename></term>
1103           <listitem>
1104             <para>This target is active whenever any graphical session is running. It is used to
1105             stop user services which only apply to a graphical (X, Wayland, etc.) session when the
1106             session is terminated. Such services should have
1107             <literal>PartOf=graphical-session.target</literal> in their [Unit]
1108             section. A target for a particular session (e. g.
1109             <filename>gnome-session.target</filename>) starts and stops
1110             <literal>graphical-session.target</literal> with
1111             <literal>BindsTo=graphical-session.target</literal>.</para>
1112
1113             <para>Which services are started by a session target is determined by the
1114             <literal>Wants=</literal> and <literal>Requires=</literal> dependencies.  For services
1115             that can be enabled independently, symlinks in <literal>.wants/</literal> and
1116             <literal>.requires/</literal> should be used, see
1117             <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1118             Those symlinks should either be shipped in packages, or should be added dynamically
1119             after installation, for example using <literal>systemctl add-wants</literal>, see
1120             <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
1121             </para>
1122
1123             <example>
1124               <title>Nautilus as part of a GNOME session</title>
1125
1126               <para><literal>gnome-session.target</literal> pulls in Nautilus as top-level service:</para>
1127
1128               <programlisting>[Unit]
1129   Description=User systemd services for GNOME graphical session
1130   Wants=nautilus.service
1131   BindsTo=graphical-session.target</programlisting>
1132
1133               <para><literal>nautilus.service</literal> gets stopped when the session stops:</para>
1134
1135               <programlisting>[Unit]
1136   Description=Render the desktop icons with Nautilus
1137   PartOf=graphical-session.target
1138
1139   [Service]
1140   …</programlisting>
1141             </example>
1142           </listitem>
1143         </varlistentry>
1144
1145         <varlistentry>
1146           <term><filename>graphical-session-pre.target</filename></term>
1147           <listitem>
1148             <para>This target contains services which set up the environment or global configuration
1149             of a graphical session, such as SSH/GPG agents (which need to export an environment
1150             variable into all desktop processes) or migration of obsolete d-conf keys after an OS
1151             upgrade (which needs to happen before starting any process that might use them). This
1152             target must be started before starting a graphical session like
1153             <filename>gnome-session.target</filename>.</para>
1154           </listitem>
1155         </varlistentry>
1156
1157         <varlistentry>
1158           <term><filename>xdg-desktop-autostart.target</filename></term>
1159           <listitem>
1160             <para>The XDG specification defines a way to autostart applications using XDG desktop files.
1161             systemd ships
1162             <citerefentry><refentrytitle>systemd-xdg-autostart-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1163             for the XDG desktop files in autostart directories.
1164             Desktop Environments can opt-in to use this service by adding a <varname>Wants=</varname>
1165             dependency on <literal>xdg-desktop-autostart.target</literal></para>.
1166           </listitem>
1167         </varlistentry>
1168       </variablelist>
1169     </refsect2>
1170   </refsect1>
1171
1172   <refsect1>
1173       <title>See Also</title>
1174       <para>
1175         <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1176         <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1177         <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1178         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1179         <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1180         <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1181         <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1182         <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1183         <citerefentry><refentrytitle>user@.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
1184       </para>
1185   </refsect1>
1186
1187 </refentry>