1 <?xml version='
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?> <!--*-nxml-*-->
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-or-later -->
6 <refentry id=
"systemd.special">
9 <title>systemd.special
</title>
10 <productname>systemd
</productname>
14 <refentrytitle>systemd.special
</refentrytitle>
15 <manvolnum>7</manvolnum>
19 <refname>systemd.special
</refname>
20 <refpurpose>Special systemd units
</refpurpose>
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>veritysetup-pre.target
</filename>,
29 <filename>veritysetup.target
</filename>,
30 <filename>ctrl-alt-del.target
</filename>,
31 <filename>blockdev@.target
</filename>,
32 <filename>boot-complete.target
</filename>,
33 <filename>default.target
</filename>,
34 <filename>emergency.target
</filename>,
35 <filename>exit.target
</filename>,
36 <filename>factory-reset.target
</filename>,
37 <filename>final.target
</filename>,
38 <filename>first-boot-complete.target
</filename>,
39 <filename>getty.target
</filename>,
40 <filename>getty-pre.target
</filename>,
41 <filename>graphical.target
</filename>,
42 <filename>halt.target
</filename>,
43 <filename>hibernate.target
</filename>,
44 <filename>hybrid-sleep.target
</filename>,
45 <filename>suspend-then-hibernate.target
</filename>,
46 <filename>initrd.target
</filename>,
47 <filename>initrd-fs.target
</filename>,
48 <filename>initrd-root-device.target
</filename>,
49 <filename>initrd-root-fs.target
</filename>,
50 <filename>initrd-usr-fs.target
</filename>,
51 <filename>kbrequest.target
</filename>,
52 <filename>kexec.target
</filename>,
53 <filename>local-fs-pre.target
</filename>,
54 <filename>local-fs.target
</filename>,
55 <filename>machines.target
</filename>
56 <filename>multi-user.target
</filename>,
57 <filename>network-online.target
</filename>,
58 <filename>network-pre.target
</filename>,
59 <filename>network.target
</filename>,
60 <filename>nss-lookup.target
</filename>,
61 <filename>nss-user-lookup.target
</filename>,
62 <filename>paths.target
</filename>,
63 <filename>poweroff.target
</filename>,
64 <filename>printer.target
</filename>,
65 <filename>reboot.target
</filename>,
66 <filename>remote-cryptsetup.target
</filename>,
67 <filename>remote-veritysetup.target
</filename>,
68 <filename>remote-fs-pre.target
</filename>,
69 <filename>remote-fs.target
</filename>,
70 <filename>rescue.target
</filename>,
71 <filename>rpcbind.target
</filename>,
72 <filename>runlevel2.target
</filename>,
73 <filename>runlevel3.target
</filename>,
74 <filename>runlevel4.target
</filename>,
75 <filename>runlevel5.target
</filename>,
76 <filename>shutdown.target
</filename>,
77 <filename>sigpwr.target
</filename>,
78 <filename>sleep.target
</filename>,
79 <filename>slices.target
</filename>,
80 <filename>smartcard.target
</filename>,
81 <filename>sockets.target
</filename>,
82 <filename>sound.target
</filename>,
83 <filename>suspend.target
</filename>,
84 <filename>swap.target
</filename>,
85 <filename>sysinit.target
</filename>,
86 <filename>system-update.target
</filename>,
87 <filename>system-update-pre.target
</filename>,
88 <filename>time-set.target
</filename>,
89 <filename>time-sync.target
</filename>,
90 <filename>timers.target
</filename>,
91 <filename>umount.target
</filename>,
92 <filename>usb-gadget.target
</filename>,
93 <!-- slices --><filename>-.slice
</filename>,
94 <filename>system.slice
</filename>,
95 <filename>user.slice
</filename>,
96 <filename>machine.slice
</filename>,
97 <!-- the rest --><filename>-.mount
</filename>,
98 <filename>dbus.service
</filename>,
99 <filename>dbus.socket
</filename>,
100 <filename>display-manager.service
</filename>,
101 <filename>init.scope
</filename>,
102 <filename>syslog.socket
</filename>,
103 <filename>system-update-cleanup.service
</filename>
104 </para></refsynopsisdiv>
107 <title>Description
</title>
109 <para>A few units are treated specially by systemd. Many of them have
110 special internal semantics and cannot be renamed, while others simply
111 have a standard meaning and should be present on all systems.
</para>
115 <title>Units managed by the system service manager
</title>
118 <title>Special System Units
</title>
122 <term><filename>-.mount
</filename></term>
124 <para>The root mount point, i.e. the mount unit for the
<filename>/
</filename>
125 path. This unit is unconditionally active, during the entire time the system is up, as
126 this mount point is where the basic userspace is running from.
</para>
131 <term><filename>basic.target
</filename></term>
133 <para>A special target unit covering basic boot-up.
</para>
135 <para>systemd automatically adds dependency of the type
136 <varname>After=
</varname> for this target unit to all
137 services (except for those with
138 <varname>DefaultDependencies=no
</varname>).
</para>
140 <para>Usually, this should pull-in all local mount points plus
141 <filename>/var/
</filename>,
<filename>/tmp/
</filename> and
142 <filename>/var/tmp/
</filename>, swap devices, sockets, timers,
143 path units and other basic initialization necessary for general
144 purpose daemons. The mentioned mount points are special cased
145 to allow them to be remote.
148 <para>This target usually does not pull in any non-target units
149 directly, but rather does so indirectly via other early boot targets.
150 It is instead meant as a synchronization point for late boot
152 <citerefentry><refentrytitle>bootup
</refentrytitle><manvolnum>7</manvolnum></citerefentry>
153 for details on the targets involved.
158 <term><filename>boot-complete.target
</filename></term>
160 <para>This target is intended as generic synchronization point for services that shall determine or act on
161 whether the boot process completed successfully. Order units that are required to succeed for a boot process
162 to be considered successful before this unit, and add a
<varname>Requires=
</varname> dependency from the
163 target unit to them. Order units that shall only run when the boot process is considered successful after the
164 target unit and pull in the target from it, also with
<varname>Requires=
</varname>. Note that by default this
165 target unit is not part of the initial boot transaction, but is supposed to be pulled in only if required by
166 units that want to run only on successful boots.
</para>
169 <citerefentry><refentrytitle>systemd-boot-check-no-failures.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
170 for a service that implements a generic system health check and orders itself before
171 <filename>boot-complete.target
</filename>.
</para>
174 <citerefentry><refentrytitle>systemd-bless-boot.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
175 for a service that propagates boot success information to the boot loader, and orders itself after
176 <filename>boot-complete.target
</filename>.
</para>
180 <term><filename>ctrl-alt-del.target
</filename></term>
182 <para>systemd starts this target whenever Control+Alt+Del is
183 pressed on the console. Usually, this should be aliased
184 (symlinked) to
<filename>reboot.target
</filename>.
</para>
188 <term><filename>cryptsetup.target
</filename></term>
190 <para>A target that pulls in setup services for all
191 encrypted block devices.
</para>
195 <term><filename>veritysetup.target
</filename></term>
197 <para>A target that pulls in setup services for all
198 verity integrity protected block devices.
</para>
202 <term><filename>dbus.service
</filename></term>
204 <para>A special unit for the D-Bus bus daemon. As soon as
205 this service is fully started up systemd will connect to it
206 and register its service.
</para>
210 <term><filename>dbus.socket
</filename></term>
212 <para>A special unit for the D-Bus system bus socket. All
213 units with
<varname>Type=dbus
</varname> automatically gain a
214 dependency on this unit.
</para>
218 <term><filename>default.target
</filename></term>
220 <para>The default unit systemd starts at bootup. Usually, this should be aliased (symlinked) to
221 <filename>multi-user.target
</filename> or
<filename>graphical.target
</filename>. See
222 <citerefentry><refentrytitle>bootup
</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
223 more discussion.
</para>
225 <para>The default unit systemd starts at bootup can be overridden with the
226 <varname>systemd.unit=
</varname> kernel command line option, or more conveniently, with the short
227 names like
<varname>single
</varname>,
<varname>rescue
</varname>,
<varname>1</varname>,
228 <varname>3</varname>,
<varname>5</varname>, …; see
229 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
233 <term><filename>display-manager.service
</filename></term>
235 <para>The display manager service. Usually, this should be
236 aliased (symlinked) to
<filename>gdm.service
</filename> or a
237 similar display manager service.
</para>
241 <term><filename>emergency.target
</filename></term>
243 <para>A special target unit that starts an emergency shell on the main console. This
244 target does not pull in other services or mounts. It is the most minimal version of
245 starting the system in order to acquire an interactive shell; the only processes running
246 are usually just the system manager (PID
1) and the shell process. This unit may be used
247 by specifying
<varname>emergency
</varname> on the kernel command line; it is
248 also used when a file system check on a required file system fails and boot-up cannot
249 continue. Compare with
<filename>rescue.target
</filename>, which serves a similar
250 purpose, but also starts the most basic services and mounts all file systems.
</para>
252 <para>In many ways booting into
<filename>emergency.target
</filename> is similar to the
253 effect of booting with
<literal>init=/bin/sh
</literal> on the kernel command line,
254 except that emergency mode provides you with the full system and service manager, and
255 allows starting individual units in order to continue the boot process in steps.
</para>
257 <para>Note that depending on how
<filename>emergency.target
</filename> is reached, the root file
258 system might be mounted read-only or read-write (no remounting is done specially for this
259 target). For example, the system may boot with root mounted read-only when
<varname>ro
</varname>
260 is used on the kernel command line and remain this way for
<filename>emergency.target
</filename>,
261 or the system may transition to
<filename>emergency.target
</filename> after the system has been
262 partially booted and disks have already been remounted read-write.
</para>
266 <term><filename>exit.target
</filename></term>
268 <para>A special service unit for shutting down the system or
269 user service manager. It is equivalent to
270 <filename>poweroff.target
</filename> on non-container
271 systems, and also works in containers.
</para>
273 <para>systemd will start this unit when it receives the
274 <constant>SIGTERM
</constant> or
<constant>SIGINT
</constant>
275 signal when running as user service daemon.
</para>
277 <para>Normally, this (indirectly) pulls in
278 <filename>shutdown.target
</filename>, which in turn should be
279 conflicted by all units that want to be scheduled for
280 shutdown when the service manager starts to exit.
</para>
284 <term><filename>factory-reset.target
</filename></term>
286 <para>A special target to trigger a factory reset.
</para>
290 <term><filename>final.target
</filename></term>
292 <para>A special target unit that is used during the shutdown
293 logic and may be used to pull in late services after all
294 normal services are already terminated and all mounts
300 <term><filename>getty.target
</filename></term>
302 <para>A special target unit that pulls in statically
303 configured local TTY
<filename>getty
</filename> instances.
308 <term><filename>graphical.target
</filename></term>
310 <para>A special target unit for setting up a graphical login
311 screen. This pulls in
312 <filename>multi-user.target
</filename>.
</para>
314 <para>Units that are needed for graphical logins shall add
315 <varname>Wants=
</varname> dependencies for their unit to
316 this unit (or
<filename>multi-user.target
</filename>) during
317 installation. This is best configured via
318 <varname>WantedBy=graphical.target
</varname> in the unit's
319 [Install] section.
</para>
323 <term><filename>hibernate.target
</filename></term>
325 <para>A special target unit for hibernating the system. This
326 pulls in
<filename>sleep.target
</filename>.
</para>
330 <term><filename>hybrid-sleep.target
</filename></term>
332 <para>A special target unit for hibernating and suspending
333 the system at the same time. This pulls in
334 <filename>sleep.target
</filename>.
</para>
338 <term><filename>suspend-then-hibernate.target
</filename></term>
340 <para>A special target unit for suspending the system for a period
341 of time, waking it and putting it into hibernate. This pulls in
342 <filename>sleep.target
</filename>.
</para>
347 <term><filename>halt.target
</filename></term>
349 <para>A special target unit for shutting down and halting
350 the system. Note that this target is distinct from
351 <filename>poweroff.target
</filename> in that it generally
352 really just halts the system rather than powering it
355 <para>Applications wanting to halt the system should not start this unit
356 directly, but should instead execute
<command>systemctl halt
</command>
357 (possibly with the
<option>--no-block
</option> option) or call
358 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
359 <command>org.freedesktop.systemd1.Manager.Halt
</command> D-Bus method
364 <term><filename>init.scope
</filename></term>
366 <para>This scope unit is where the system and service manager (PID
1) itself resides. It
367 is active as long as the system is running.
</para>
371 <term><filename>initrd.target
</filename></term>
373 <para>This is the default target in the initramfs, similar to
<filename>default.target
</filename>
374 in the main system. It is used to mount the real root and transition to it. See
375 <citerefentry><refentrytitle>bootup
</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
376 more discussion.
</para>
380 <term><filename>initrd-fs.target
</filename></term>
382 <para><citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
383 automatically adds dependencies of type
<varname>Before=
</varname> to
384 <filename>sysroot-usr.mount
</filename> and all mount points found in
385 <filename>/etc/fstab
</filename> that have the
<option>x-initrd.mount
</option> mount option set
386 and do not have the
<option>noauto
</option> mount option set. It is also indirectly ordered after
387 <filename>sysroot.mount
</filename>. Thus, once this target is reached the
388 <filename>/sysroot/
</filename> hierarchy is fully set up, in preparation for the transition to
393 <term><filename>initrd-root-device.target
</filename></term>
395 <para>A special initrd target unit that is reached when the root filesystem device is available, but before
397 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
399 <citerefentry><refentrytitle>systemd-gpt-auto-generator
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
400 automatically setup the appropriate dependencies to make this happen.
405 <term><filename>initrd-root-fs.target
</filename></term>
407 <para><citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
408 automatically adds dependencies of type
<varname>Before=
</varname> to the
409 <filename>sysroot.mount
</filename> unit, which is generated from the kernel command line's
410 <varname>root=
</varname> setting (or equivalent).
</para>
414 <term><filename>initrd-usr-fs.target
</filename></term>
416 <para><citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
417 automatically adds dependencies of type
<varname>Before=
</varname> to the
418 <filename>sysusr-usr.mount
</filename> unit, which is generated from the kernel command line's
419 <varname>usr=
</varname> switch. Services may order themselves after this target unit in order to
420 run once the
<filename>/sysusr/
</filename> hierarchy becomes available, on systems that come up
421 initially without a root file system, but with an initialized
<filename>/usr/
</filename> and need
422 to access that before setting up the root file system to ultimately switch to. On systems where
423 <varname>usr=
</varname> is not used this target is ordered after
424 <filename>sysroot.mount
</filename> and thus mostly equivalent to
425 <filename>initrd-root-fs.target
</filename>. In effect on any system once this target is reached
426 the file system backing
<filename>/usr/
</filename> is mounted, though possibly at two different
427 locations, either below the
<filename>/sysusr/
</filename> or the
<filename>/sysroot/
</filename>
432 <term><filename>kbrequest.target
</filename></term>
434 <para>systemd starts this target whenever Alt+ArrowUp is
435 pressed on the console. Note that any user with physical access
436 to the machine will be able to do this, without authentication,
437 so this should be used carefully.
</para>
441 <term><filename>kexec.target
</filename></term>
443 <para>A special target unit for shutting down and rebooting
444 the system via kexec.
</para>
446 <para>Applications wanting to reboot the system should not start this unit
447 directly, but should instead execute
<command>systemctl kexec
</command>
448 (possibly with the
<option>--no-block
</option> option) or call
449 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
450 <command>org.freedesktop.systemd1.Manager.KExec
</command> D-Bus method
455 <term><filename>local-fs.target
</filename></term>
457 <para><citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>3</manvolnum></citerefentry>
458 automatically adds dependencies of type
459 <varname>Before=
</varname> to all mount units that refer to
460 local mount points for this target unit. In addition, it
461 adds dependencies of type
<varname>Wants=
</varname> to this
462 target unit for those mounts listed in
463 <filename>/etc/fstab
</filename> that have the
464 <option>auto
</option> mount option set.
</para>
468 <term><filename>machines.target
</filename></term>
470 <para>A standard target unit for starting all the containers
471 and other virtual machines. See
<filename>systemd-nspawn@.service
</filename>
472 for an example.
</para>
476 <term><filename>multi-user.target
</filename></term>
478 <para>A special target unit for setting up a multi-user
479 system (non-graphical). This is pulled in by
480 <filename>graphical.target
</filename>.
</para>
482 <para>Units that are needed for a multi-user system shall
483 add
<varname>Wants=
</varname> dependencies for their unit to
484 this unit during installation. This is best configured via
485 <varname>WantedBy=multi-user.target
</varname> in the unit's
486 [Install] section.
</para>
490 <term><filename>network-online.target
</filename></term>
492 <para>Units that strictly require a configured network
493 connection should pull in
494 <filename>network-online.target
</filename> (via a
495 <varname>Wants=
</varname> type dependency) and order
496 themselves after it. This target unit is intended to pull in
497 a service that delays further execution until the network is
498 sufficiently set up. What precisely this requires is left to
499 the implementation of the network managing service.
</para>
501 <para>Note the distinction between this unit and
502 <filename>network.target
</filename>. This unit is an active
503 unit (i.e. pulled in by the consumer rather than the
504 provider of this functionality) and pulls in a service which
505 possibly adds substantial delays to further execution. In
506 contrast,
<filename>network.target
</filename> is a passive
507 unit (i.e. pulled in by the provider of the functionality,
508 rather than the consumer) that usually does not delay
509 execution much. Usually,
<filename>network.target
</filename>
510 is part of the boot of most systems, while
511 <filename>network-online.target
</filename> is not, except
512 when at least one unit requires it. Also see
<ulink
513 url=
"https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
514 Services After the Network is up
</ulink> for more
517 <para>All mount units for remote network file systems automatically pull in this unit, and order
518 themselves after it. Note that networking daemons that simply
<emphasis>provide
</emphasis>
519 functionality to other hosts (as opposed to
<emphasis>consume
</emphasis> functionality of other
520 hosts) generally do not need to pull this in.
</para>
522 <para>systemd automatically adds dependencies of type
<varname>Wants=
</varname> and
523 <varname>After=
</varname> for this target unit to all SysV init script service units
524 with an LSB header referring to the
<literal>$network
</literal> facility.
</para>
526 <para>Note that this unit is only useful during the original system start-up
527 logic. After the system has completed booting up, it will not track the online state of
528 the system anymore. Due to this it cannot be used as a network connection monitor
529 concept, it is purely a one-time system start-up concept.
</para>
533 <term><filename>paths.target
</filename></term>
535 <para>A special target unit that sets up all path units (see
536 <citerefentry><refentrytitle>systemd.path
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
537 for details) that shall be active after boot.
</para>
539 <para>It is recommended that path units installed by
540 applications get pulled in via
<varname>Wants=
</varname>
541 dependencies from this unit. This is best configured via a
542 <varname>WantedBy=paths.target
</varname> in the path unit's
543 [Install] section.
</para>
547 <term><filename>poweroff.target
</filename></term>
549 <para>A special target unit for shutting down and powering
550 off the system.
</para>
552 <para>Applications wanting to power off the system should not start this unit
553 directly, but should instead execute
<command>systemctl poweroff
</command>
554 (possibly with the
<option>--no-block
</option> option) or call
555 <citerefentry><refentrytitle>systemd-logind
</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
556 <command>org.freedesktop.login1.Manager.PowerOff
</command> D-Bus method
559 <para><filename>runlevel0.target
</filename> is an alias for
560 this target unit, for compatibility with SysV.
</para>
564 <term><filename>reboot.target
</filename></term>
566 <para>A special target unit for shutting down and rebooting
569 <para>Applications wanting to reboot the system should not start this unit
570 directly, but should instead execute
<command>systemctl reboot
</command>
571 (possibly with the
<option>--no-block
</option> option) or call
572 <citerefentry><refentrytitle>systemd-logind
</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
573 <command>org.freedesktop.login1.Manager.Reboot
</command> D-Bus method
576 <para><filename>runlevel6.target
</filename> is an alias for
577 this target unit, for compatibility with SysV.
</para>
581 <term><filename>remote-cryptsetup.target
</filename></term>
583 <para>Similar to
<filename>cryptsetup.target
</filename>, but for encrypted
584 devices which are accessed over the network. It is used for
585 <citerefentry><refentrytitle>crypttab
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
586 entries marked with
<option>_netdev
</option>.
</para>
590 <term><filename>remote-veritysetup.target
</filename></term>
592 <para>Similar to
<filename>veritysetup.target
</filename>, but for verity
593 integrity protected devices which are accessed over the network. It is used for
594 <citerefentry><refentrytitle>veritytab
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
595 entries marked with
<option>_netdev
</option>.
</para>
599 <term><filename>remote-fs.target
</filename></term>
601 <para>Similar to
<filename>local-fs.target
</filename>, but
602 for remote mount points.
</para>
604 <para>systemd automatically adds dependencies of type
605 <varname>After=
</varname> for this target unit to all SysV
606 init script service units with an LSB header referring to
607 the
<literal>$remote_fs
</literal> facility.
</para>
611 <term><filename>rescue.target
</filename></term>
613 <para>A special target unit that pulls in the base system (including system mounts) and
614 spawns a rescue shell. Isolate to this target in order to administer the system in
615 single-user mode with all file systems mounted but with no services running, except for
616 the most basic. Compare with
<filename>emergency.target
</filename>, which is much more
617 reduced and does not provide the file systems or most basic services. Compare with
618 <filename>multi-user.target
</filename>, this target could be seen as
619 <filename>single-user.target
</filename>.
</para>
621 <para><filename>runlevel1.target
</filename> is an alias for this target unit, for
622 compatibility with SysV.
</para>
624 <para>Use the
<literal>systemd.unit=rescue.target
</literal> kernel command line option
625 to boot into this mode. A short alias for this kernel command line option is
626 <literal>1</literal>, for compatibility with SysV.
</para>
630 <term><filename>runlevel2.target
</filename></term>
631 <term><filename>runlevel3.target
</filename></term>
632 <term><filename>runlevel4.target
</filename></term>
633 <term><filename>runlevel5.target
</filename></term>
635 <para>These are targets that are called whenever the SysV
636 compatibility code asks for runlevel
2,
3,
4,
5,
637 respectively. It is a good idea to make this an alias for
638 (i.e. symlink to)
<filename>graphical.target
</filename>
639 (for runlevel
5) or
<filename>multi-user.target
</filename>
644 <term><filename>shutdown.target
</filename></term>
646 <para>A special target unit that terminates the services on
647 system shutdown.
</para>
649 <para>Services that shall be terminated on system shutdown
650 shall add
<varname>Conflicts=
</varname> and
651 <varname>Before=
</varname> dependencies to this unit for
652 their service unit, which is implicitly done when
653 <varname>DefaultDependencies=yes
</varname> is set (the
658 <term><filename>sigpwr.target
</filename></term>
660 <para>A special target that is started when systemd receives
661 the SIGPWR process signal, which is normally sent by the
662 kernel or UPS daemons when power fails.
</para>
666 <term><filename>sleep.target
</filename></term>
668 <para>A special target unit that is pulled in by
669 <filename>suspend.target
</filename>,
670 <filename>hibernate.target
</filename> and
671 <filename>hybrid-sleep.target
</filename> and may be used to
672 hook units into the sleep state logic.
</para>
676 <term><filename>slices.target
</filename></term>
678 <para>A special target unit that sets up all slice units (see
679 <citerefentry><refentrytitle>systemd.slice
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
680 for details) that shall always be active after boot. By default the generic
681 <filename>system.slice
</filename> slice unit as well as the root slice unit
682 <filename>-.slice
</filename> are pulled in and ordered before this unit (see
685 <para>Adding slice units to
<filename>slices.target
</filename> is generally not
686 necessary. Instead, when some unit that uses
<varname>Slice=
</varname> is started, the
687 specified slice will be started automatically. Adding
688 <varname>WantedBy=slices.target
</varname> lines to the [Install]
689 section should only be done for units that need to be always active. In that case care
690 needs to be taken to avoid creating a loop through the automatic dependencies on
691 "parent" slices.
</para>
695 <term><filename>sockets.target
</filename></term>
697 <para>A special target unit that sets up all socket
699 <citerefentry><refentrytitle>systemd.socket
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
700 for details) that shall be active after boot.
</para>
702 <para>Services that can be socket-activated shall add
703 <varname>Wants=
</varname> dependencies to this unit for
704 their socket unit during installation. This is best
705 configured via a
<varname>WantedBy=sockets.target
</varname>
706 in the socket unit's [Install]
711 <term><filename>suspend.target
</filename></term>
713 <para>A special target unit for suspending the system. This
714 pulls in
<filename>sleep.target
</filename>.
</para>
718 <term><filename>swap.target
</filename></term>
720 <para>Similar to
<filename>local-fs.target
</filename>, but
721 for swap partitions and swap files.
</para>
725 <term><filename>sysinit.target
</filename></term>
727 <para>systemd automatically adds dependencies of the types
728 <varname>Requires=
</varname> and
<varname>After=
</varname>
729 for this target unit to all services (except for those with
730 <varname>DefaultDependencies=no
</varname>).
</para>
732 <para>This target pulls in the services required for system
733 initialization. System services pulled in by this target should
734 declare
<varname>DefaultDependencies=no
</varname> and specify
735 all their dependencies manually, including access to anything
736 more than a read only root filesystem. For details on the
737 dependencies of this target, refer to
738 <citerefentry><refentrytitle>bootup
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
743 <term><filename>syslog.socket
</filename></term>
745 <para>The socket unit syslog implementations should listen
746 on. All userspace log messages will be made available on
747 this socket. For more information about syslog integration,
748 please consult the
<ulink
749 url=
"https://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog
750 Interface
</ulink> document.
</para>
754 <term><filename>system-update.target
</filename></term>
755 <term><filename>system-update-pre.target
</filename></term>
756 <term><filename>system-update-cleanup.service
</filename></term>
758 <para>A special target unit that is used for offline system updates.
759 <citerefentry><refentrytitle>systemd-system-update-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
760 will redirect the boot process to this target if
<filename>/system-update
</filename>
761 exists. For more information see
762 <citerefentry><refentrytitle>systemd.offline-updates
</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
765 <para>Updates should happen before the
<filename>system-update.target
</filename> is
766 reached, and the services which implement them should cause the machine to reboot. The
767 main units executing the update should order themselves after
768 <filename>system-update-pre.target
</filename> but not pull it in. Services which want to
769 run during system updates only, but before the actual system update is executed should
770 order themselves before this unit and pull it in. As a safety measure, if this does not
771 happen, and
<filename>/system-update
</filename> still exists after
772 <filename>system-update.target
</filename> is reached,
773 <filename>system-update-cleanup.service
</filename> will remove this symlink and reboot
778 <term><filename>timers.target
</filename></term>
780 <para>A special target unit that sets up all timer units
782 <citerefentry><refentrytitle>systemd.timer
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
783 for details) that shall be active after boot.
</para>
785 <para>It is recommended that timer units installed by
786 applications get pulled in via
<varname>Wants=
</varname>
787 dependencies from this unit. This is best configured via
788 <varname>WantedBy=timers.target
</varname> in the timer
789 unit's [Install] section.
</para>
793 <term><filename>umount.target
</filename></term>
795 <para>A special target unit that unmounts all mount and
796 automount points on system shutdown.
</para>
798 <para>Mounts that shall be unmounted on system shutdown
799 shall add Conflicts dependencies to this unit for their
800 mount unit, which is implicitly done when
801 <varname>DefaultDependencies=yes
</varname> is set (the
810 <title>Special System Units for Devices
</title>
812 <para>Some target units are automatically pulled in as devices of
813 certain kinds show up in the system. These may be used to
814 automatically activate various services based on the specific type
815 of the available hardware.
</para>
819 <term><filename>bluetooth.target
</filename></term>
821 <para>This target is started automatically as soon as a
822 Bluetooth controller is plugged in or becomes available at
825 <para>This may be used to pull in Bluetooth management
826 daemons dynamically when Bluetooth hardware is found.
</para>
830 <term><filename>printer.target
</filename></term>
832 <para>This target is started automatically as soon as a
833 printer is plugged in or becomes available at boot.
</para>
835 <para>This may be used to pull in printer management daemons
836 dynamically when printer hardware is found.
</para>
840 <term><filename>smartcard.target
</filename></term>
842 <para>This target is started automatically as soon as a
843 smartcard controller is plugged in or becomes available at
846 <para>This may be used to pull in smartcard management
847 daemons dynamically when smartcard hardware is found.
</para>
851 <term><filename>sound.target
</filename></term>
853 <para>This target is started automatically as soon as a
854 sound card is plugged in or becomes available at
857 <para>This may be used to pull in audio management daemons
858 dynamically when audio hardware is found.
</para>
862 <term><filename>usb-gadget.target
</filename></term>
864 <para>This target is started automatically as soon as a
865 USB Device Controller becomes available at boot.
</para>
867 <para>This may be used to pull in usb gadget
868 dynamically when UDC hardware is found.
</para>
875 <title>Special Passive System Units
</title>
877 <para>A number of special system targets are defined that can be
878 used to properly order boot-up of optional services. These targets
879 are generally not part of the initial boot transaction, unless
880 they are explicitly pulled in by one of the implementing services.
881 Note specifically that these
<emphasis>passive
</emphasis> target
882 units are generally not pulled in by the consumer of a service,
883 but by the provider of the service. This means: a consuming
884 service should order itself after these targets (as appropriate),
885 but not pull it in. A providing service should order itself before
886 these targets (as appropriate) and pull it in (via a
887 <varname>Wants=
</varname> type dependency).
</para>
889 <para>Note that these passive units cannot be started manually,
890 i.e.
<literal>systemctl start time-sync.target
</literal> will fail
891 with an error. They can only be pulled in by dependency. This is
892 enforced since they exist for ordering purposes only and thus are
893 not useful as only unit within a transaction.
</para>
897 <term><filename>blockdev@.target
</filename></term>
898 <listitem><para>This template unit is used to order mount units and other consumers of block
899 devices after services that synthesize these block devices. In particular, this is intended to be
900 used with storage services (such as
901 <citerefentry><refentrytitle>systemd-cryptsetup@.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>/
902 <citerefentry><refentrytitle>systemd-veritysetup@.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
903 that allocate and manage a virtual block device. Storage services are ordered before an instance of
904 <filename>blockdev@.target
</filename>, and the consumer units after it. The ordering is
905 particularly relevant during shutdown, as it ensures that the mount is deactivated first and the
906 service backing the mount later. The
<filename>blockdev@.target
</filename> instance should be
907 pulled in via a
<option>Wants=
</option> dependency of the storage daemon and thus generally not be
908 part of any transaction unless a storage daemon is used. The instance name for instances of this
909 template unit must be a properly escaped block device node path, e.g.
910 <filename index=
"false">blockdev@dev-mapper-foobar.target
</filename> for the storage device
911 <filename index=
"false">/dev/mapper/foobar
</filename>.
</para></listitem>
914 <term><filename>cryptsetup-pre.target
</filename></term>
916 <para>This passive target unit may be pulled in by services
917 that want to run before any encrypted block device is set
918 up. All encrypted block devices are set up after this target
919 has been reached. Since the shutdown order is implicitly the
920 reverse start-up order between units, this target is
921 particularly useful to ensure that a service is shut down
922 only after all encrypted block devices are fully
927 <term><filename>veritysetup-pre.target
</filename></term>
929 <para>This passive target unit may be pulled in by services
930 that want to run before any verity integrity protected block
931 device is set up. All verity integrity protected block
932 devices are set up after this target has been reached. Since
933 the shutdown order is implicitly the reverse start-up order
934 between units, this target is particularly useful to ensure
935 that a service is shut down only after all verity integrity
936 protected block devices are fully stopped.
</para>
940 <term><filename>first-boot-complete.target
</filename></term>
942 <para>This passive target is intended as a synchronization point for units that need to run once
943 during the first boot. Only after all units ordered before this target have finished, will the
944 <citerefentry><refentrytitle>machine-id
</refentrytitle><manvolnum>5</manvolnum></citerefentry>
945 be committed to disk, marking the first boot as completed. If the boot is aborted at any time
946 before that, the next boot will re-run any units with
<varname>ConditionFirstBoot=yes
</varname>.
951 <term><filename>getty-pre.target
</filename></term>
953 <para>A special passive target unit. Users of this target
954 are expected to pull it in the boot transaction via
955 a dependency (e.g.
<varname>Wants=
</varname>). Order your
956 unit before this unit if you want to make use of the console
957 just before
<filename>getty
</filename> is started.
962 <term><filename>local-fs-pre.target
</filename></term>
964 <para>This target unit is
965 automatically ordered before
966 all local mount points marked
967 with
<option>auto
</option>
968 (see above). It can be used to
969 execute certain units before
970 all local mounts.
</para>
974 <term><filename>network.target
</filename></term>
976 <para>This unit is supposed to indicate when network functionality is available, but it is only
977 very weakly defined what that is supposed to mean. However, the following should apply at
981 <listitem><para>At start-up, any configured synthetic network devices (i.e. not physical ones
982 that require hardware to show up and be probed, but virtual ones like bridge devices and
983 similar which are created programmatically) that do not depend on any underlying hardware
984 should be allocated by the time this target is reached. It is not necessary for these
985 interfaces to also have completed IP level configuration by the time
986 <filename>network.target
</filename> is reached.
</para></listitem>
988 <listitem><para>At shutdown, a unit that is ordered after
<filename>network.target
</filename>
989 will be stopped before the network — to whatever level it might be set up by then — is shut
990 down. It is hence useful when writing service files that require network access on shutdown,
991 which should order themselves after this target, but not pull it in. Also see
<ulink
992 url=
"https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running Services After
993 the Network is up
</ulink> for more information.
</para></listitem>
996 <para>It must emphasized that at start-up there's no guarantee that hardware-based devices have
997 shown up by the time this target is reached, or even acquired complete IP configuration. For that
998 purpose use
<filename>network-online.target
</filename> as described above.
</para>
1002 <term><filename>network-pre.target
</filename></term>
1004 <para>This passive target unit may be pulled in by services
1005 that want to run before any network is set up, for example
1006 for the purpose of setting up a firewall. All network
1007 management software orders itself after this target, but
1008 does not pull it in.
</para>
1012 <term><filename>nss-lookup.target
</filename></term>
1014 <para>A target that should be used as synchronization point for all host/network name
1015 service lookups. Note that this is independent of UNIX user/group name lookups for which
1016 <filename>nss-user-lookup.target
</filename> should be used. All services for which the
1017 availability of full host/network name resolution is essential should be ordered after
1018 this target, but not pull it in. systemd automatically adds dependencies of type
1019 <varname>After=
</varname> for this target unit to all SysV init script service units
1020 with an LSB header referring to the
<literal>$named
</literal> facility.
</para>
1024 <term><filename>nss-user-lookup.target
</filename></term>
1026 <para>A target that should be used as synchronization point for all regular UNIX
1027 user/group name service lookups. Note that this is independent of host/network name
1028 lookups for which
<filename>nss-lookup.target
</filename> should be used. All services
1029 for which the availability of the full user/group database is essential should be
1030 ordered after this target, but not pull it in. All services which provide parts of the
1031 user/group database should be ordered before this target, and pull it in. Note that this
1032 unit is only relevant for regular users and groups — system users and groups are
1033 required to be resolvable during earliest boot already, and hence do not need any
1034 special ordering against this target.
</para>
1038 <term><filename>remote-fs-pre.target
</filename></term>
1040 <para>This target unit is automatically ordered before all
1041 mount point units (see above) and cryptsetup/veritysetup devices
1042 marked with the
<option>_netdev
</option>. It can be used to run
1043 certain units before remote encrypted devices and mounts are established.
1044 Note that this unit is generally not part of the initial
1045 transaction, unless the unit that wants to be ordered before
1046 all remote mounts pulls it in via a
1047 <varname>Wants=
</varname> type dependency. If the unit wants
1048 to be pulled in by the first remote mount showing up, it
1049 should use
<filename>network-online.target
</filename> (see
1054 <term><filename>rpcbind.target
</filename></term>
1056 <para>The portmapper/rpcbind pulls in this target and orders
1057 itself before it, to indicate its availability. systemd
1058 automatically adds dependencies of type
1059 <varname>After=
</varname> for this target unit to all SysV
1060 init script service units with an LSB header referring to
1061 the
<literal>$portmap
</literal> facility.
</para>
1065 <term><filename>time-set.target
</filename></term>
1067 <para>Services responsible for setting the system clock (
<constant>CLOCK_REALTIME
</constant>)
1068 from a local source (such as a maintained timestamp file or imprecise real-time clock) should
1069 pull in this target and order themselves before it. Services where approximate, roughly monotonic
1070 time is desired should be ordered after this unit, but not pull it in.
</para>
1072 <para>This target does not provide the accuracy guarantees of
1073 <filename>time-sync.target
</filename> (see below), however does not depend on remote clock
1074 sources to be reachable, i.e. the target is typically not delayed by network problems and
1075 similar. Use of this target is recommended for services where approximate clock accuracy and
1076 rough monotonicity is desired but activation shall not be delayed for possibly unreliable network
1077 communication.
</para>
1079 <para>The service manager automatically adds dependencies of type
<varname>After=
</varname> for
1080 this target unit to all timer units with at least one
<varname>OnCalendar=
</varname>
1084 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1085 service is a simple daemon that pulls in this target and orders itself before it. Besides
1086 implementing the SNTP network protocol it maintains a timestamp file on disk whose modification
1087 time is regularlary updated. At service start-up the local system clock is set from that modification time,
1088 ensuring it increases roughly monotonically.
</para>
1090 <para>Note that ordering a unit after
<filename>time-set.target
</filename> only has effect if
1091 there's actually a service ordered before it that delays it until the clock is adjusted for rough
1092 monotonicity. Otherwise, this target might get reached before the clock is adjusted to be roughly
1094 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1095 or an alternative NTP implementation to delay the target.
</para>
1099 <term><filename>time-sync.target
</filename></term>
1101 <para>Services indicating completed synchronization of the system clock
1102 (
<constant>CLOCK_REALTIME
</constant>) to a remote source should pull in this target and order
1103 themselves before it. Services where accurate time is essential should be ordered after this
1104 unit, but not pull it in.
</para>
1106 <para>The service manager automatically adds dependencies of type
<varname>After=
</varname> for
1107 this target unit to all SysV init script service units with an LSB header referring to the
1108 <literal>$time
</literal> facility, as well to all timer units with at least one
1109 <varname>OnCalendar=
</varname> directive.
</para>
1111 <para>This target provides stricter clock accuracy guarantees than
1112 <filename>time-set.target
</filename> (see above), but likely requires
1113 network communication and thus introduces unpredictable delays.
1114 Services that require clock accuracy and where network
1115 communication delays are acceptable should use this target. Services that require a less accurate
1116 clock, and only approximate and roughly monotonic clock behaviour should use
1117 <filename>time-set.target
</filename> instead.
</para>
1119 <para>Note that ordering a unit after
<filename>time-sync.target
</filename> only has effect if
1120 there's actually a service ordered before it that delays it until clock synchronization is
1121 reached. Otherwise, this target might get reached before the clock is synchronized to any remote
1122 accurate reference clock. When using
1123 <citerefentry><refentrytitle>systemd-timesyncd.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1125 <citerefentry><refentrytitle>systemd-time-wait-sync.service
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1126 to delay the target; or use an equivalent service for other NTP implementations.
</para>
1129 <title>Comparison
</title>
1130 <tgroup cols='
2' align='left' colsep='
1' rowsep='
1'
>
1131 <colspec colname=
"time-set" />
1132 <colspec colname=
"time-sync" />
1135 <entry><filename>time-set.target
</filename></entry>
1136 <entry><filename>time-sync.target
</filename></entry>
1141 <entry>"quick" to reach
</entry>
1142 <entry>"slow" to reach
</entry>
1145 <entry>typically uses local clock sources, boot process not affected by availability of external resources
</entry>
1146 <entry>typically uses remote clock sources, inserts dependencies on remote resources into boot process
</entry>
1149 <entry>reliable, because local
</entry>
1150 <entry>unreliable, because typically network involved
</entry>
1153 <entry>typically guarantees an approximate and roughly monotonic clock only
</entry>
1154 <entry>typically guarantees an accurate clock
</entry>
1157 <entry>implemented by
<filename>systemd-timesyncd.service
</filename></entry>
1158 <entry>implemented by
<filename>systemd-time-wait-sync.service
</filename></entry>
1170 <title>Special Slice Units
</title>
1172 <para>There are four
<literal>.slice
</literal> units which form the basis of the hierarchy for
1173 assignment of resources for services, users, and virtual machines or containers. See
1174 <citerefentry><refentrytitle>systemd.slice
</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1175 for details about slice units.
</para>
1179 <term><filename>-.slice
</filename></term>
1181 <para>The root slice is the root of the slice hierarchy. It usually does not contain
1182 units directly, but may be used to set defaults for the whole tree.
</para>
1187 <term><filename>system.slice
</filename></term>
1189 <para>By default, all system services started by
1190 <command>systemd
</command> are found in this slice.
</para>
1195 <term><filename>user.slice
</filename></term>
1197 <para>By default, all user processes and services started on
1198 behalf of the user, including the per-user systemd instance
1199 are found in this slice. This is pulled in by
1200 <filename>systemd-logind.service
</filename>.
</para>
1205 <term><filename>machine.slice
</filename></term>
1207 <para>By default, all virtual machines and containers
1208 registered with
<command>systemd-machined
</command> are
1209 found in this slice. This is pulled in by
1210 <filename>systemd-machined.service
</filename>.
</para>
1218 <title>Units managed by the user service manager
</title>
1221 <title>Special User Units
</title>
1223 <para>When systemd runs as a user instance, the following special
1224 units are available:
</para>
1228 <term><filename>default.target
</filename></term>
1230 <para>This is the main target of the user session, started by default. Various services that
1231 compose the normal user session should be pulled into this target. In this regard,
1232 <filename>default.target
</filename> is similar to
<filename>multi-user.target
</filename> in the
1233 system instance, but it is a real unit, not an alias.
</para>
1238 <para>In addition, the following units are available which have definitions similar to their
1239 system counterparts:
1240 <filename>exit.target
</filename>,
1241 <filename>shutdown.target
</filename>,
1242 <filename>sockets.target
</filename>,
1243 <filename>timers.target
</filename>,
1244 <filename>paths.target
</filename>,
1245 <filename>bluetooth.target
</filename>,
1246 <filename>printer.target
</filename>,
1247 <filename>smartcard.target
</filename>,
1248 <filename>sound.target
</filename>.
</para>
1252 <title>Special Passive User Units
</title>
1256 <term><filename>graphical-session.target
</filename></term>
1258 <para>This target is active whenever any graphical session is running. It is used to
1259 stop user services which only apply to a graphical (X, Wayland, etc.) session when the
1260 session is terminated. Such services should have
1261 <literal>PartOf=graphical-session.target
</literal> in their [Unit]
1262 section. A target for a particular session (e. g.
1263 <filename>gnome-session.target
</filename>) starts and stops
1264 <literal>graphical-session.target
</literal> with
1265 <literal>BindsTo=graphical-session.target
</literal>.
</para>
1267 <para>Which services are started by a session target is determined by the
1268 <literal>Wants=
</literal> and
<literal>Requires=
</literal> dependencies. For services
1269 that can be enabled independently, symlinks in
<literal>.wants/
</literal> and
1270 <literal>.requires/
</literal> should be used, see
1271 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
1272 Those symlinks should either be shipped in packages, or should be added dynamically
1273 after installation, for example using
<literal>systemctl add-wants
</literal>, see
1274 <citerefentry><refentrytitle>systemctl
</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
1278 <title>Nautilus as part of a GNOME session
</title>
1280 <para><literal>gnome-session.target
</literal> pulls in Nautilus as top-level service:
</para>
1282 <programlisting>[Unit]
1283 Description=User systemd services for GNOME graphical session
1284 Wants=nautilus.service
1285 BindsTo=graphical-session.target
</programlisting>
1287 <para><literal>nautilus.service
</literal> gets stopped when the session stops:
</para>
1289 <programlisting>[Unit]
1290 Description=Render the desktop icons with Nautilus
1291 PartOf=graphical-session.target
1300 <term><filename>graphical-session-pre.target
</filename></term>
1302 <para>This target contains services which set up the environment or global configuration
1303 of a graphical session, such as SSH/GPG agents (which need to export an environment
1304 variable into all desktop processes) or migration of obsolete d-conf keys after an OS
1305 upgrade (which needs to happen before starting any process that might use them). This
1306 target must be started before starting a graphical session like
1307 <filename>gnome-session.target
</filename>.
</para>
1312 <term><filename>xdg-desktop-autostart.target
</filename></term>
1314 <para>The XDG specification defines a way to autostart applications using XDG desktop files.
1316 <citerefentry><refentrytitle>systemd-xdg-autostart-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1317 for the XDG desktop files in autostart directories. Desktop Environments can opt-in to use this
1318 service by adding a
<varname>Wants=
</varname> dependency on
1319 <filename>xdg-desktop-autostart.target
</filename>.
</para>
1326 <title>Special User Slice Units
</title>
1328 <para>There are four
<literal>.slice
</literal> units which form the basis of the user hierarchy for
1329 assignment of resources for user applications and services. See
1330 <citerefentry><refentrytitle>systemd.slice
</refentrytitle><manvolnum>7</manvolnum></citerefentry>
1331 for details about slice units and the documentation about
1332 <ulink url=
"https://systemd.io/DESKTOP_ENVIRONMENTS">Desktop Environments
</ulink>
1333 for further information.
</para>
1337 <term><filename>-.slice
</filename></term>
1339 <para>The root slice is the root of the user's slice hierarchy.
1340 It usually does not contain units directly, but may be used to set defaults for the whole tree.
</para>
1345 <term><filename>app.slice
</filename></term>
1347 <para>By default, all user services and applications managed by
1348 <command>systemd
</command> are found in this slice.
1349 All interactively launched applications like web browsers and text editors
1350 as well as non-critical services should be placed into this slice.
</para>
1355 <term><filename>session.slice
</filename></term>
1357 <para>All essential services and applications required for the
1358 session should use this slice.
1359 These are services that either cannot be restarted easily
1360 or where latency issues may affect the interactivity of the system and applications.
1361 This includes the display server, screen readers and other services such as DBus or XDG portals.
1362 Such services should be configured to be part of this slice by
1363 adding
<varname>Slice=session.slice
</varname> to their unit files.
</para>
1368 <term><filename>background.slice
</filename></term>
1370 <para>All services running low-priority background tasks should use this slice.
1371 This permits resources to be preferentially assigned to the other slices.
1372 Examples include non-interactive tasks like file indexing or backup operations
1373 where latency is not important.
</para>
1381 <title>See Also
</title>
1383 <citerefentry><refentrytitle>systemd
</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1384 <citerefentry><refentrytitle>systemd.unit
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1385 <citerefentry><refentrytitle>systemd.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1386 <citerefentry><refentrytitle>systemd.socket
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1387 <citerefentry><refentrytitle>systemd.target
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1388 <citerefentry><refentrytitle>systemd.slice
</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1389 <citerefentry><refentrytitle>bootup
</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1390 <citerefentry><refentrytitle>systemd-fstab-generator
</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
1391 <citerefentry><refentrytitle>user@.service
</refentrytitle><manvolnum>5</manvolnum></citerefentry>