1
<?xml version='1.0'?> <!--*-nxml-*-->
2
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
3
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
6
This file is part of systemd.
8
Copyright 2010 Lennart Poettering
10
systemd is free software; you can redistribute it and/or modify it
11
under the terms of the GNU General Public License as published by
12
the Free Software Foundation; either version 2 of the License, or
13
(at your option) any later version.
15
systemd is distributed in the hope that it will be useful, but
16
WITHOUT ANY WARRANTY; without even the implied warranty of
17
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18
General Public License for more details.
20
You should have received a copy of the GNU General Public License
21
along with systemd; If not, see <http://www.gnu.org/licenses/>.
24
<refentry id="systemd.special">
27
<title>systemd.special</title>
28
<productname>systemd</productname>
32
<contrib>Developer</contrib>
33
<firstname>Lennart</firstname>
34
<surname>Poettering</surname>
35
<email>lennart@poettering.net</email>
41
<refentrytitle>systemd.special</refentrytitle>
42
<manvolnum>7</manvolnum>
46
<refname>systemd.special</refname>
47
<refpurpose>special systemd units</refpurpose>
51
<para><filename>basic.target</filename>,
52
<filename>ctrl-alt-del.target</filename>,
53
<filename>dbus.service</filename>,
54
<filename>default.target</filename>,
55
<filename>display-manager.service</filename>,
56
<filename>emergency.target</filename>,
57
<filename>exit.service</filename>,
58
<filename>graphical.target</filename>,
59
<filename>halt.target</filename>,
60
<filename>kbrequest.target</filename>,
61
<filename>local-fs.target</filename>,
62
<filename>local-fs-pre.target</filename>,
63
<filename>mail-transfer-agent.target</filename>,
64
<filename>multi-user.target</filename>,
65
<filename>network.target</filename>,
66
<filename>nss-lookup.target</filename>,
67
<filename>poweroff.target</filename>,
68
<filename>reboot.target</filename>,
69
<filename>remote-fs.target</filename>,
70
<filename>remote-fs-pre.target</filename>,
71
<filename>rescue.target</filename>,
72
<filename>rpcbind.target</filename>,
73
<filename>runlevel2.target</filename>,
74
<filename>runlevel3.target</filename>,
75
<filename>runlevel4.target</filename>,
76
<filename>runlevel5.target</filename>,
77
<filename>shutdown.target</filename>,
78
<filename>sigpwr.target</filename>,
79
<filename>sockets.target</filename>,
80
<filename>swap.target</filename>,
81
<filename>sysinit.target</filename>,
82
<filename>syslog.target</filename>,
83
<filename>systemd-initctl.service</filename>,
84
<filename>systemd-initctl.socket</filename>,
85
<filename>systemd-stdout-syslog-bridge.service</filename>,
86
<filename>systemd-stdout-syslog-bridge.socket</filename>,
87
<filename>time-sync.target</filename>,
88
<filename>umount.target</filename></para>
92
<title>Description</title>
94
<para>A few units are treated specially by
95
systemd. They have special internal semantics and
96
cannot be renamed.</para>
100
<title>Special System Units</title>
104
<term><filename>basic.target</filename></term>
106
<para>A special target unit
107
covering early boot-up.</para>
108
<para>systemd automatically
109
adds dependencies of the types
110
Requires and After for this
111
target unit to all SysV
112
service units configured for
113
runlevel 1 to 5.</para>
114
<para>Usually this should pull-in
115
all sockets, mount points,
116
swap devices and other basic
117
initialization necessary for
119
daemons. Most normal daemons
120
should have dependencies of
121
type After and Requires on
126
<term><filename>ctrl-alt-del.target</filename></term>
128
<para>systemd starts this
130
Control+Alt+Del is pressed on
131
the console. Usually this
132
should be aliased (symlinked)
134
<filename>reboot.target</filename>.</para>
138
<term><filename>dbus.service</filename></term>
140
<para>A special unit for the
141
D-Bus system bus. As soon as
142
this service is fully started
143
up systemd will connect to it
149
<term><filename>default.target</filename></term>
151
<para>The default unit systemd
152
starts at bootup. Usually this
153
should be aliased (symlinked)
155
<filename>multi-user.target</filename>
157
<filename>graphical.target</filename>.</para>
158
<para>The default unit systemd
159
starts at bootup can be
161
<varname>systemd.unit=</varname>
162
kernel command line option.</para>
166
<term><filename>display-manager.service</filename></term>
168
<para>The display manager
169
service. Usually this should
170
be aliased (symlinked) to
171
<filename>xdm.service</filename>
172
or a similar display manager
174
<para>systemd automatically
175
adds dependencies of type
176
After for this target unit to
177
all SysV init script service
178
units with a LSB header
180
<literal>$x-display-manager</literal>
181
facility, for compatibility
186
<term><filename>emergency.target</filename></term>
188
<para>A special target unit
189
that starts an emergency
191
console. This unit is supposed
192
to be used with the kernel
194
<varname>systemd.unit=</varname>
195
and has otherwise little use.
200
<term><filename>graphical.target</filename></term>
202
<para>A special target unit
203
for setting up a graphical
204
login screen. This pulls in
205
<filename>multi-user.target</filename>.</para>
207
<para>Units that are needed
208
for graphical login shall add
209
Wants dependencies for their
210
unit to this unit (or
211
<filename>multi-user.target</filename>)
212
during installation.</para>
216
<term><filename>halt.target</filename></term>
218
<para>A special target unit
219
for shutting down and halting the system.</para>
221
<para>Applications wanting to
222
halt the system should start
227
<term><filename>kbrequest.target</filename></term>
229
<para>systemd starts this
230
target whenever Alt+ArrowUp is
231
pressed on the console. This
232
is a good candidate to be
233
aliased (symlinked) to
234
<filename>rescue.target</filename>.</para>
238
<term><filename>local-fs.target</filename></term>
240
<para>systemd automatically
241
adds dependencies of type
242
After to all mount units that
243
refer to local mount points
244
for this target unit. In
245
addition, systemd adds
246
dependencies of type Wants to
247
this target unit for those
249
<filename>/etc/fstab</filename>
251
<option>auto</option> and
252
<option>comment=systemd.mount</option>
253
mount options set.</para>
255
<para>systemd automatically
256
adds dependencies of type
257
After for this target unit to
258
all SysV init script service
259
units with an LSB header
261
<literal>$local_fs</literal>
266
<term><filename>local-fs-pre.target</filename></term>
268
<para>This target unit is
269
automatically ordered before
270
all local mount points marked
271
with <option>auto</option>
272
(see above). It can be used to
273
execute certain units before
274
all local mounts.</para>
278
<term><filename>mail-transfer-agent.target</filename></term>
280
<para>The mail transfer agent
281
(MTA) service. Usually this
282
should pull-in all units
284
sending/receiving mails on the
287
<para>systemd automatically
288
adds dependencies of type
289
After for this target unit to
290
all SysV init script service
291
units with an LSB header
293
<literal>$mail-transfer-agent</literal>
295
<literal>$mail-transport-agent</literal>
296
facilities, for compatibility
301
<term><filename>multi-user.target</filename></term>
303
<para>A special target unit
304
for setting up a multi-user
305
system (non-graphical). This
307
<filename>graphical.target</filename>.</para>
309
<para>Units that are needed
310
for a multi-user system shall
311
add Wants dependencies to
312
this unit for their unit during
317
<term><filename>network.target</filename></term>
319
<para>systemd automatically
320
adds dependencies of type
321
After for this target unit to
322
all SysV init script service
323
units with an LSB header
325
<literal>$network</literal>
330
<term><filename>nss-lookup.target</filename></term>
332
<para>systemd automatically
333
adds dependencies of type
334
After for this target unit to
335
all SysV init script service
336
units with an LSB header
338
<literal>$named</literal>
343
<term><filename>poweroff.target</filename></term>
345
<para>A special target unit
346
for shutting down and powering off the system.</para>
348
<para>Applications wanting to
349
power off the system should start
352
<para><filename>runlevel0.target</filename>
353
is an alias for this target
354
unit, for compatibility with SysV.</para>
358
<term><filename>reboot.target</filename></term>
360
<para>A special target unit
361
for shutting down and rebooting the system.</para>
363
<para>Applications wanting to
364
reboot the system should start
367
<para><filename>runlevel6.target</filename>
368
is an alias for this target
369
unit, for compatibility with SysV.</para>
373
<term><filename>remote-fs.target</filename></term>
376
<filename>local-fs.target</filename>,
380
<para>systemd automatically
381
adds dependencies of type
382
After for this target unit to
383
all SysV init script service
384
units with an LSB header
386
<literal>$remote_fs</literal>
391
<term><filename>remote-fs-pre.target</filename></term>
393
<para>This target unit is
394
automatically ordered before
395
all remote mount points marked
396
with <option>auto</option>
397
(see above). It can be used to
398
execute certain units before
399
all remote mounts.</para>
403
<term><filename>rescue.target</filename></term>
405
<para>A special target unit
406
for setting up the base system
407
and a rescue shell.</para>
409
<para><filename>runlevel1.target</filename>
410
is an alias for this target
411
unit, for compatibility with SysV.</para>
415
<term><filename>rpcbind.target</filename></term>
417
<para>systemd automatically
418
adds dependencies of type
419
After for this target unit to
420
all SysV init script service
421
units with an LSB header
423
<literal>$rpcbind</literal>
428
<term><filename>runlevel2.target</filename></term>
430
<para>This is a target that is
431
called whenever the SysV
432
compatibility code asks for
433
runlevel 2. It is a good idea
434
to make this an alias for
436
<filename>multi-user.target</filename>.</para>
440
<term><filename>runlevel3.target</filename></term>
442
<para>This is a target that is
443
called whenever the SysV
444
compatibility code asks for
445
runlevel 3. It is a good idea
446
to make this an alias for
448
<filename>multi-user.target</filename>
450
<filename>graphical.target</filename>.</para>
454
<term><filename>runlevel4.target</filename></term>
456
<para>This is a target that is
457
called whenever the SysV
458
compatibility code asks for
459
runlevel 4. It is a good idea
460
to make this an alias for
462
<filename>multi-user.target</filename>
464
<filename>graphical.target</filename>.</para>
468
<term><filename>runlevel5.target</filename></term>
470
<para>This is a target that is
471
called whenever the SysV
472
compatibility code asks for
473
runlevel 5. It is a good idea
474
to make this an alias for
476
<filename>multi-user.target</filename>
478
<filename>graphical.target</filename>.</para>
482
<term><filename>shutdown.target</filename></term>
484
<para>A special target unit
485
that terminates the services
486
on system shutdown.</para>
488
<para>Services that shall be
489
terminated on system shutdown
491
dependencies to this unit for
492
their service unit, which is
494
<varname>DefaultDependencies=yes</varname>
495
is set (the default).</para>
497
<para>systemd automatically
498
adds dependencies of type
499
Conflicts to this target unit
500
for all SysV init script
501
service units that shall be
502
terminated in SysV runlevels 0
507
<term><filename>sigpwr.target</filename></term>
509
<para>A special target that is
510
started when systemd receives
511
the SIGPWR process signal,
512
which is normally sent by the
513
kernel or UPS daemons when
518
<term><filename>sockets.target</filename></term>
520
<para>A special target unit
521
that sets up all service
524
<para>Services that can be
525
socket-activated shall add
526
Wants dependencies to this
527
unit for their socket unit
528
during installation.</para>
532
<term><filename>swap.target</filename></term>
535
<filename>local-fs.target</filename>, but for swap
541
<term><filename>sysinit.target</filename></term>
543
<para>A special target unit
544
covering early boot-up scripts.</para>
545
<para>systemd automatically
546
adds dependencies of the types
547
Wants and After for all
548
SysV service units configured
549
for runlevels that are not 0
550
to 6 to this target unit.
551
This covers the special
552
boot-up runlevels some
553
distributions have, such as S
558
<term><filename>syslog.target</filename></term>
560
<para>systemd automatically
561
adds dependencies of type
562
After for this target unit to
563
all SysV init script service
564
units with an LSB header
566
<literal>$syslog</literal>
571
<term><filename>systemd-initctl.service</filename></term>
574
compatibility with the SysV
575
/dev/initctl file system FIFO
576
for communication with the
579
socket-activated service, see
580
<filename>system-initctl.socket</filename>.</para>
584
<term><filename>systemd-initctl.socket</filename></term>
586
<para>Socket activation unit
588
<filename>system-initctl.service</filename>.</para>
592
<term><filename>systemd-stdout-syslog-bridge.service</filename></term>
594
<para>This is internally used
595
by systemd to provide syslog
596
logging to the processes it
599
socket-activated service, see
600
<filename>system-stdout-syslog-bridge.socket</filename>.</para>
604
<term><filename>systemd-stdout-syslog-bridge.socket</filename></term>
606
<para>Socket activation unit
608
<filename>system-stdout-syslog-bridge.service</filename>. systemd
609
will automatically add
610
dependencies of types Requires
611
and After to all units that
612
have been configured for
613
stdout or stderr to be
614
connected to syslog or the
615
kernel log buffer.</para>
619
<term><filename>systemd-shutdownd.service</filename></term>
621
<para>This is internally used
623
<citerefentry><refentrytitle>shutdown</refentrytitle><manvolnum>8</manvolnum></citerefentry>
624
to implement delayed shutdowns.</para>
626
socket-activated service, see
627
<filename>system-shutdownd.socket</filename>.</para>
631
<term><filename>systemd-shutdownd.socket</filename></term>
633
<para>Socket activation unit
635
<filename>system-shutdownd.service</filename>.</para>
639
<term><filename>time-sync.target</filename></term>
641
<para>systemd automatically
642
adds dependencies of type
643
After for this target unit to
644
all SysV init script service
645
units with an LSB header
647
<literal>$time</literal>
652
<term><filename>umount.target</filename></term>
654
<para>A special target unit
655
that umounts all mount and
656
automount points on system
659
<para>Mounts that shall be
660
unmounted on system shutdown
662
dependencies to this unit for
663
their mount unit, which is
665
<varname>DefaultDependencies=yes</varname>
666
is set (the default).</para>
673
<title>Special User Units</title>
675
<para>When systemd runs as a user instance, the
676
following special units are available, which have
677
similar definitions as their system counterparts:
678
<filename>default.target</filename>,
679
<filename>local-fs.target</filename>,
680
<filename>remote-fs.target</filename>,
681
<filename>shutdown.target</filename>,
682
<filename>sockets.target</filename>,
683
<filename>swap.target</filename>.</para>
685
<para>In addition the following special unit is
686
understood only when systemd runs as service instance:</para>
690
<term><filename>exit.service</filename></term>
692
<para>A special service unit
693
for shutting down the
694
user service manager.</para>
696
<para>Applications wanting to
697
terminate the user service
698
manager should start this
699
unit. If systemd receives
700
SIGTERM or SIGINT when running
701
as user service daemon it will
702
start this unit.</para>
704
<para>Normally, this pulls in
705
<filename>shutdown.target</filename>
706
which in turn should be
707
conflicted by all units that
708
want to be shut down on
709
user service manager exit.</para>
716
<title>See Also</title>
718
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
719
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
720
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
721
<citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>
added
removed
man/systemd.special.xml
