1SYSTEMD.SPECIAL(7) systemd.special SYSTEMD.SPECIAL(7)
2
6 systemd.special - Special systemd units
7
9 basic.target, bluetooth.target, ctrl-alt-del.target, cryptsetup.target,
10 cryptsetup-pre.target, dbus.service, dbus.socket, default.target,
11 display-manager.service, emergency.target, exit.target, final.target,
12 getty.target, getty-pre.target, graphical.target, halt.target,
13 hibernate.target, hybrid-sleep.target, initrd-fs.target,
14 kbrequest.target, kexec.target, local-fs.target, local-fs-pre.target,
15 multi-user.target, network.target, network-online.target,
16 network-pre.target, nss-lookup.target, nss-user-lookup.target,
17 paths.target, poweroff.target, printer.target, reboot.target,
18 remote-cryptsetup.target, remote-fs.target, remote-fs-pre.target,
19 rescue.target, initrd-root-fs.target, rpcbind.target, runlevel2.target,
20 runlevel3.target, runlevel4.target, runlevel5.target, shutdown.target,
21 sigpwr.target, sleep.target, smartcard.target, sockets.target,
22 sound.target, suspend.target, swap.target, sysinit.target,
23 syslog.socket, system-update.target, time-sync.target, timers.target,
24 umount.target, -.slice, system.slice, user.slice, machine.slice
25
27 A few units are treated specially by systemd. They have special
28 internal semantics and cannot be renamed.
29
31 basic.target
32 A special target unit covering basic boot-up.
33 systemd automatically adds dependencies of the types Requires= and
35 After= for this target unit to all services (except for those with
36 DefaultDependencies=no).
37 Usually this should pull-in all mount points, swap devices,
39 sockets, timers, and path units and other basic initialization
40 necessary for general purpose daemons.
41 ctrl-alt-del.target
43 systemd starts this target whenever Control+Alt+Del is pressed on
44 the console. Usually this should be aliased (symlinked) to
45 reboot.target.
46 cryptsetup.target
48 A target that pulls in setup services for all encrypted block
49 devices.
50 dbus.service
52 A special unit for the D-Bus bus daemon. As soon as this service is
53 fully started up systemd will connect to it and register its
54 service.
55 dbus.socket
57 A special unit for the D-Bus system bus socket. All units with
58 Type=dbus automatically gain a dependency on this unit.
59 default.target
61 The default unit systemd starts at bootup. Usually this should be
62 aliased (symlinked) to multi-user.target or graphical.target.
63 The default unit systemd starts at bootup can be overridden with
65 the systemd.unit= kernel command line option.
66 display-manager.service
68 The display manager service. Usually this should be aliased
69 (symlinked) to gdm.service or a similar display manager service.
70 emergency.target
72 A special target unit that starts an emergency shell on the main
73 console. This unit is supposed to be used with the kernel command
74 line option systemd.unit= and has otherwise little use.
75 final.target
77 A special target unit that is used during the shutdown logic and
78 may be used to pull in late services after all normal services are
79 already terminated and all mounts unmounted.
80 getty.target
82 A special target unit that pulls in statically configured local TTY
83 getty instances.
84 getty-pre.target
86 A special passive target unit. Users of this target are expected to
87 pull it in the boot transaction via a dependency (e.g. Wants=).
88 Order your unit before this unit if you want to make use of the
89 console just before getty is started.
90 graphical.target
92 A special target unit for setting up a graphical login screen. This
93 pulls in multi-user.target.
94 Units that are needed for graphical logins shall add Wants=
96 dependencies for their unit to this unit (or multi-user.target)
97 during installation. This is best configured via
98 WantedBy=graphical.target in the unit's "[Install]" section.
99 hibernate.target
101 A special target unit for hibernating the system. This pulls in
102 sleep.target.
103 hybrid-sleep.target
105 A special target unit for hibernating and suspending the system at
106 the same time. This pulls in sleep.target.
107 halt.target
109 A special target unit for shutting down and halting the system.
110 Note that this target is distinct from poweroff.target in that it
111 generally really just halts the system rather than powering it
112 down.
113 Applications wanting to halt the system should start this unit.
115 initrd-fs.target
117 systemd-fstab-generator(3) automatically adds dependencies of type
118 Before= to sysroot-usr.mount and all mount points found in
119 /etc/fstab that have x-initrd.mount and not have noauto mount
120 options set.
121 kbrequest.target
123 systemd starts this target whenever Alt+ArrowUp is pressed on the
124 console. This is a good candidate to be aliased (symlinked) to
125 rescue.target.
126 kexec.target
128 A special target unit for shutting down and rebooting the system
129 via kexec.
130 Applications wanting to reboot the system with kexec should start
132 this unit.
133 local-fs.target
135 systemd-fstab-generator(3) automatically adds dependencies of type
136 Before= to all mount units that refer to local mount points for
137 this target unit. In addition, it adds dependencies of type Wants=
138 to this target unit for those mounts listed in /etc/fstab that have
139 the auto mount option set.
140 multi-user.target
142 A special target unit for setting up a multi-user system
143 (non-graphical). This is pulled in by graphical.target.
144 Units that are needed for a multi-user system shall add Wants=
146 dependencies for their unit to this unit during installation. This
147 is best configured via WantedBy=multi-user.target in the unit's
148 "[Install]" section.
149 network-online.target
151 Units that strictly require a configured network connection should
152 pull in network-online.target (via a Wants= type dependency) and
153 order themselves after it. This target unit is intended to pull in
154 a service that delays further execution until the network is
155 sufficiently set up. What precisely this requires is left to the
156 implementation of the network managing service.
157 Note the distinction between this unit and network.target. This
159 unit is an active unit (i.e. pulled in by the consumer rather than
160 the provider of this functionality) and pulls in a service which
161 possibly adds substantial delays to further execution. In contrast,
162 network.target is a passive unit (i.e. pulled in by the provider of
163 the functionality, rather than the consumer) that usually does not
164 delay execution much. Usually, network.target is part of the boot
165 of most systems, while network-online.target is not, except when at
166 least one unit requires it. Also see Running Services After the
167 Network is up[1] for more information.
168 All mount units for remote network file systems automatically pull
170 in this unit, and order themselves after it. Note that networking
171 daemons that simply provide functionality to other hosts generally
172 do not need to pull this in.
173 paths.target
175 A special target unit that sets up all path units (see
176 systemd.path(5) for details) that shall be active after boot.
177 It is recommended that path units installed by applications get
179 pulled in via Wants= dependencies from this unit. This is best
180 configured via a WantedBy=paths.target in the path unit's
181 "[Install]" section.
182 poweroff.target
184 A special target unit for shutting down and powering off the
185 system.
186 Applications wanting to power off the system should start this
188 unit.
189 runlevel0.target is an alias for this target unit, for
191 compatibility with SysV.
192 reboot.target
194 A special target unit for shutting down and rebooting the system.
195 Applications wanting to reboot the system should start this unit.
197 runlevel6.target is an alias for this target unit, for
199 compatibility with SysV.
200 remote-cryptsetup.target
202 Similar to cryptsetup.target, but for encrypted devices which are
203 accessed over the network. It is used for crypttab(8) entries
204 marked with _netdev.
205 remote-fs.target
207 Similar to local-fs.target, but for remote mount points.
208 systemd automatically adds dependencies of type After= for this
210 target unit to all SysV init script service units with an LSB
211 header referring to the "$remote_fs" facility.
212 rescue.target
214 A special target unit for setting up the base system and a rescue
215 shell.
216 runlevel1.target is an alias for this target unit, for
218 compatibility with SysV.
219 initrd-root-fs.target
221 systemd-fstab-generator(3) automatically adds dependencies of type
222 Before= to the sysroot.mount unit, which is generated from the
223 kernel command line.
224 runlevel2.target, runlevel3.target, runlevel4.target, runlevel5.target
226 These are targets that are called whenever the SysV compatibility
227 code asks for runlevel 2, 3, 4, 5, respectively. It is a good idea
228 to make this an alias for (i.e. symlink to) multi-user.target (for
229 runlevel 2) or graphical.target (the others).
230 shutdown.target
232 A special target unit that terminates the services on system
233 shutdown.
234 Services that shall be terminated on system shutdown shall add
236 Conflicts= dependencies to this unit for their service unit, which
237 is implicitly done when DefaultDependencies=yes is set (the
238 default).
239 sigpwr.target
241 A special target that is started when systemd receives the SIGPWR
242 process signal, which is normally sent by the kernel or UPS daemons
243 when power fails.
244 sleep.target
246 A special target unit that is pulled in by suspend.target,
247 hibernate.target and hybrid-sleep.target and may be used to hook
248 units into the sleep state logic.
249 sockets.target
251 A special target unit that sets up all socket units.(see
252 systemd.socket(5) for details) that shall be active after boot.
253 Services that can be socket-activated shall add Wants= dependencies
255 to this unit for their socket unit during installation. This is
256 best configured via a WantedBy=sockets.target in the socket unit's
257 "[Install]" section.
258 suspend.target
260 A special target unit for suspending the system. This pulls in
261 sleep.target.
262 swap.target
264 Similar to local-fs.target, but for swap partitions and swap files.
265 sysinit.target
267 A special target unit covering early boot-up scripts.
268 syslog.socket
270 The socket unit syslog implementations should listen on. All
271 userspace log messages will be made available on this socket. For
272 more information about syslog integration, please consult the
273 Syslog Interface[2] document.
274 system-update.target
276 A special target unit that is used for off-line system updates.
277 systemd-system-update-generator(8) will redirect the boot process
278 to this target if /system-update exists. For more information see
279 the System Updates Specification[3].
280 timers.target
282 A special target unit that sets up all timer units (see
283 systemd.timer(5) for details) that shall be active after boot.
284 It is recommended that timer units installed by applications get
286 pulled in via Wants= dependencies from this unit. This is best
287 configured via WantedBy=timers.target in the timer unit's
288 "[Install]" section.
289 umount.target
291 A special target unit that umounts all mount and automount points
292 on system shutdown.
293 Mounts that shall be unmounted on system shutdown shall add
295 Conflicts dependencies to this unit for their mount unit, which is
296 implicitly done when DefaultDependencies=yes is set (the default).
297
299 Some target units are automatically pulled in as devices of certain
300 kinds show up in the system. These may be used to automatically
301 activate various services based on the specific type of the available
302 hardware.
303 bluetooth.target
305 This target is started automatically as soon as a Bluetooth
306 controller is plugged in or becomes available at boot.
307 This may be used to pull in Bluetooth management daemons
309 dynamically when Bluetooth hardware is found.
310 printer.target
312 This target is started automatically as soon as a printer is
313 plugged in or becomes available at boot.
314 This may be used to pull in printer management daemons dynamically
316 when printer hardware is found.
317 smartcard.target
319 This target is started automatically as soon as a smartcard
320 controller is plugged in or becomes available at boot.
321 This may be used to pull in smartcard management daemons
323 dynamically when smartcard hardware is found.
324 sound.target
326 This target is started automatically as soon as a sound card is
327 plugged in or becomes available at boot.
328 This may be used to pull in audio management daemons dynamically
330 when audio hardware is found.
331
333 A number of special system targets are defined that can be used to
334 properly order boot-up of optional services. These targets are
335 generally not part of the initial boot transaction, unless they are
336 explicitly pulled in by one of the implementing services. Note
337 specifically that these passive target units are generally not pulled
338 in by the consumer of a service, but by the provider of the service.
339 This means: a consuming service should order itself after these targets
340 (as appropriate), but not pull it in. A providing service should order
341 itself before these targets (as appropriate) and pull it in (via a
342 Wants= type dependency).
343 Note that these passive units cannot be started manually, i.e.
345 "systemctl start time-sync.target" will fail with an error. They can
346 only be pulled in by dependency. This is enforced since they exist for
347 ordering purposes only and thus are not useful as only unit within a
348 transaction.
349 cryptsetup-pre.target
351 This passive target unit may be pulled in by services that want to
352 run before any encrypted block device is set up. All encrypted
353 block devices are set up after this target has been reached. Since
354 the shutdown order is implicitly the reverse start-up order between
355 units, this target is particularly useful to ensure that a service
356 is shut down only after all encrypted block devices are fully
357 stopped.
358 local-fs-pre.target
360 This target unit is automatically ordered before all local mount
361 points marked with auto (see above). It can be used to execute
362 certain units before all local mounts.
363 network.target
365 This unit is supposed to indicate when network functionality is
366 available, but it is only very weakly defined what that is supposed
367 to mean, with one exception: at shutdown, a unit that is ordered
368 after network.target will be stopped before the network -- to
369 whatever level it might be set up then -- is shut down. It is hence
370 useful when writing service files that require network access on
371 shutdown, which should order themselves after this target, but not
372 pull it in. Also see Running Services After the Network is up[1]
373 for more information. Also see network-online.target described
374 above.
375 systemd automatically adds dependencies of type After= for this
377 target unit to all SysV init script service units with an LSB
378 header referring to the "$network" facility.
379 network-pre.target
381 This passive target unit may be pulled in by services that want to
382 run before any network is set up, for example for the purpose of
383 setting up a firewall. All network management software orders
384 itself after this target, but does not pull it in.
385 nss-lookup.target
387 A target that should be used as synchronization point for all
388 host/network name service lookups. Note that this is independent of
389 user/group name lookups for which nss-user-lookup.target should be
390 used. All services for which the availability of full host/network
391 name resolution is essential should be ordered after this target,
392 but not pull it in. systemd automatically adds dependencies of type
393 After= for this target unit to all SysV init script service units
394 with an LSB header referring to the "$named" facility.
395 nss-user-lookup.target
397 A target that should be used as synchronization point for all
398 user/group name service lookups. Note that this is independent of
399 host/network name lookups for which nss-lookup.target should be
400 used. All services for which the availability of the full
401 user/group database is essential should be ordered after this
402 target, but not pull it in. Note that system users are always
403 resolvable, and hence do not require any special ordering against
404 this target.
405 remote-fs-pre.target
407 This target unit is automatically ordered before all mount point
408 units (see above) and cryptsetup devices marked with the _netdev.
409 It can be used to run certain units before remote encrypted devices
410 and mounts are established. Note that this unit is generally not
411 part of the initial transaction, unless the unit that wants to be
412 ordered before all remote mounts pulls it in via a Wants= type
413 dependency. If the unit wants to be pulled in by the first remote
414 mount showing up, it should use network-online.target (see above).
415 rpcbind.target
417 The portmapper/rpcbind pulls in this target and orders itself
418 before it, to indicate its availability. systemd automatically adds
419 dependencies of type After= for this target unit to all SysV init
420 script service units with an LSB header referring to the "$portmap"
421 facility.
422 time-sync.target
424 Services responsible for synchronizing the system clock from a
425 remote source (such as NTP client implementations) should pull in
426 this target and order themselves before it. All services where
427 correct time is essential should be ordered after this unit, but
428 not pull it in. systemd automatically adds dependencies of type
429 After= for this target unit to all SysV init script service units
430 with an LSB header referring to the "$time" facility.
431
433 There are four ".slice" units which form the basis of the hierarchy for
434 assignment of resources for services, users, and virtual machines or
435 containers.
436 -.slice
438 The root slice is the root of the hierarchy. It usually does not
439 contain units directly, but may be used to set defaults for the
440 whole tree.
441 system.slice
443 By default, all services services started by systemd are found in
444 this slice.
445 user.slice
447 By default, all user processes started on behalf of the user are
448 found in this slice.
449 machine.slice
451 By default, all virtual machines and containers registered with
452 systemd-machined are found in this slice.
453
455 systemd(1), systemd.unit(5), systemd.service(5), systemd.socket(5),
456 systemd.target(5), systemd.slice(5), bootup(7), systemd-fstab-
457 generator(8)
458
460 1. Running Services After the Network is up
461 http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget
462 2. Syslog Interface
464 http://www.freedesktop.org/wiki/Software/systemd/syslog
465 3. System Updates Specification
467 http://freedesktop.org/wiki/Software/systemd/SystemUpdates
468systemd 219 SYSTEMD.SPECIAL(7)