1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
|
<?xml version='1.0'?> <!--*-nxml-*-->
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!-- SPDX-License-Identifier: LGPL-2.1+ -->
<refentry id="systemd.special">
<refentryinfo>
<title>systemd.special</title>
<productname>systemd</productname>
</refentryinfo>
<refmeta>
<refentrytitle>systemd.special</refentrytitle>
<manvolnum>7</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd.special</refname>
<refpurpose>Special systemd units</refpurpose>
</refnamediv>
<refsynopsisdiv><para>
<!-- sort alphabetically, targets first --><filename>basic.target</filename>,
<filename>bluetooth.target</filename>,
<filename>cryptsetup-pre.target</filename>,
<filename>cryptsetup.target</filename>,
<filename>ctrl-alt-del.target</filename>,
<filename>blockdev@.target</filename>,
<filename>boot-complete.target</filename>,
<filename>default.target</filename>,
<filename>emergency.target</filename>,
<filename>exit.target</filename>,
<filename>final.target</filename>,
<filename>getty.target</filename>,
<filename>getty-pre.target</filename>,
<filename>graphical.target</filename>,
<filename>halt.target</filename>,
<filename>hibernate.target</filename>,
<filename>hybrid-sleep.target</filename>,
<filename>suspend-then-hibernate.target</filename>,
<filename>initrd.target</filename>,
<filename>initrd-fs.target</filename>,
<filename>initrd-root-device.target</filename>,
<filename>initrd-root-fs.target</filename>,
<filename>kbrequest.target</filename>,
<filename>kexec.target</filename>,
<filename>local-fs-pre.target</filename>,
<filename>local-fs.target</filename>,
<filename>machines.target</filename>
<filename>multi-user.target</filename>,
<filename>network-online.target</filename>,
<filename>network-pre.target</filename>,
<filename>network.target</filename>,
<filename>nss-lookup.target</filename>,
<filename>nss-user-lookup.target</filename>,
<filename>paths.target</filename>,
<filename>poweroff.target</filename>,
<filename>printer.target</filename>,
<filename>reboot.target</filename>,
<filename>remote-cryptsetup.target</filename>,
<filename>remote-fs-pre.target</filename>,
<filename>remote-fs.target</filename>,
<filename>rescue.target</filename>,
<filename>rpcbind.target</filename>,
<filename>runlevel2.target</filename>,
<filename>runlevel3.target</filename>,
<filename>runlevel4.target</filename>,
<filename>runlevel5.target</filename>,
<filename>shutdown.target</filename>,
<filename>sigpwr.target</filename>,
<filename>sleep.target</filename>,
<filename>slices.target</filename>,
<filename>smartcard.target</filename>,
<filename>sockets.target</filename>,
<filename>sound.target</filename>,
<filename>suspend.target</filename>,
<filename>swap.target</filename>,
<filename>sysinit.target</filename>,
<filename>system-update.target</filename>,
<filename>system-update-pre.target</filename>,
<filename>time-set.target</filename>,
<filename>time-sync.target</filename>,
<filename>timers.target</filename>,
<filename>umount.target</filename>,
<filename>usb-gadget.target</filename>,
<!-- slices --><filename>-.slice</filename>,
<filename>system.slice</filename>,
<filename>user.slice</filename>,
<filename>machine.slice</filename>,
<!-- the rest --><filename>-.mount</filename>,
<filename>dbus.service</filename>,
<filename>dbus.socket</filename>,
<filename>display-manager.service</filename>,
<filename>init.scope</filename>,
<filename>syslog.socket</filename>,
<filename>system-update-cleanup.service</filename>
</para></refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>A few units are treated specially by systemd. Many of them have
special internal semantics and cannot be renamed, while others simply
have a standard meaning and should be present on all systems.</para>
</refsect1>
<refsect1>
<title>Units managed by the system's service manager</title>
<refsect2>
<title>Special System Units</title>
<variablelist>
<varlistentry>
<term><filename>-.mount</filename></term>
<listitem>
<para>The root mount point, i.e. the mount unit for the <filename>/</filename>
path. This unit is unconditionally active, during the entire time the system is up, as
this mount point is where the basic userspace is running from.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>basic.target</filename></term>
<listitem>
<para>A special target unit covering basic boot-up.</para>
<para>systemd automatically adds dependency of the type
<varname>After=</varname> for this target unit to all
services (except for those with
<varname>DefaultDependencies=no</varname>).</para>
<para>Usually, this should pull-in all local mount points plus
<filename>/var</filename>, <filename>/tmp</filename> and
<filename>/var/tmp</filename>, swap devices, sockets, timers,
path units and other basic initialization necessary for general
purpose daemons. The mentioned mount points are special cased
to allow them to be remote.
</para>
<para>This target usually does not pull in any non-target units
directly, but rather does so indirectly via other early boot targets.
It is instead meant as a synchronization point for late boot
services. Refer to
<citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for details on the targets involved.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>boot-complete.target</filename></term>
<listitem>
<para>This target is intended as generic synchronization point for services that shall determine or act on
whether the boot process completed successfully. Order units that are required to succeed for a boot process
to be considered successful before this unit, and add a <varname>Requires=</varname> dependency from the
target unit to them. Order units that shall only run when the boot process is considered successful after the
target unit and pull in the target from it, also with <varname>Requires=</varname>. Note that by default this
target unit is not part of the initial boot transaction, but is supposed to be pulled in only if required by
units that want to run only on successful boots.</para>
<para>See
<citerefentry><refentrytitle>systemd-boot-check-no-failures.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for a service that implements a generic system health check and orders itself before
<filename>boot-complete.target</filename>.</para>
<para>See
<citerefentry><refentrytitle>systemd-bless-boot.service</refentrytitle><manvolnum>8</manvolnum></citerefentry>
for a service that propagates boot success information to the boot loader, and orders itself after
<filename>boot-complete.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>ctrl-alt-del.target</filename></term>
<listitem>
<para>systemd starts this target whenever Control+Alt+Del is
pressed on the console. Usually, this should be aliased
(symlinked) to <filename>reboot.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>cryptsetup.target</filename></term>
<listitem>
<para>A target that pulls in setup services for all
encrypted block devices.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>dbus.service</filename></term>
<listitem>
<para>A special unit for the D-Bus bus daemon. As soon as
this service is fully started up systemd will connect to it
and register its service.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>dbus.socket</filename></term>
<listitem>
<para>A special unit for the D-Bus system bus socket. All
units with <varname>Type=dbus</varname> automatically gain a
dependency on this unit.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>default.target</filename></term>
<listitem>
<para>The default unit systemd starts at bootup. Usually, this should be aliased (symlinked) to
<filename>multi-user.target</filename> or <filename>graphical.target</filename>. See
<citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
more discussion.</para>
<para>The default unit systemd starts at bootup can be overridden with the
<varname>systemd.unit=</varname> kernel command line option, or more conveniently, with the short
names like <varname>single</varname>, <varname>rescue</varname>, <varname>1</varname>,
<varname>3</varname>, <varname>5</varname>, …; see
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>display-manager.service</filename></term>
<listitem>
<para>The display manager service. Usually, this should be
aliased (symlinked) to <filename>gdm.service</filename> or a
similar display manager service.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>emergency.target</filename></term>
<listitem>
<para>A special target unit that starts an emergency shell on the main console. This
target does not pull in any services or mounts. It is the most minimal version of
starting the system in order to acquire an interactive shell; the only processes running
are usually just the system manager (PID 1) and the shell process. This unit is supposed
to be used with the kernel command line option <varname>systemd.unit=</varname>; it is
also used when a file system check on a required file system fails, and boot-up cannot
continue. Compare with <filename>rescue.target</filename>, which serves a similar
purpose, but also starts the most basic services and mounts all file systems.</para>
<para>Use the <literal>systemd.unit=emergency.target</literal> kernel command line
option to boot into this mode. A short alias for this kernel command line option is
<literal>emergency</literal>, for compatibility with SysV.</para>
<para>In many ways booting into <filename>emergency.target</filename> is similar to the
effect of booting with <literal>init=/bin/sh</literal> on the kernel command line,
except that emergency mode provides you with the full system and service manager, and
allows starting individual units in order to continue the boot process in steps.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>exit.target</filename></term>
<listitem>
<para>A special service unit for shutting down the system or
user service manager. It is equivalent to
<filename>poweroff.target</filename> on non-container
systems, and also works in containers.</para>
<para>systemd will start this unit when it receives the
<constant>SIGTERM</constant> or <constant>SIGINT</constant>
signal when running as user service daemon.</para>
<para>Normally, this (indirectly) pulls in
<filename>shutdown.target</filename>, which in turn should be
conflicted by all units that want to be scheduled for
shutdown when the service manager starts to exit.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>final.target</filename></term>
<listitem>
<para>A special target unit that is used during the shutdown
logic and may be used to pull in late services after all
normal services are already terminated and all mounts
unmounted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>getty.target</filename></term>
<listitem>
<para>A special target unit that pulls in statically
configured local TTY <filename>getty</filename> instances.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>graphical.target</filename></term>
<listitem>
<para>A special target unit for setting up a graphical login
screen. This pulls in
<filename>multi-user.target</filename>.</para>
<para>Units that are needed for graphical logins shall add
<varname>Wants=</varname> dependencies for their unit to
this unit (or <filename>multi-user.target</filename>) during
installation. This is best configured via
<varname>WantedBy=graphical.target</varname> in the unit's
<literal>[Install]</literal> section.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>hibernate.target</filename></term>
<listitem>
<para>A special target unit for hibernating the system. This
pulls in <filename>sleep.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>hybrid-sleep.target</filename></term>
<listitem>
<para>A special target unit for hibernating and suspending
the system at the same time. This pulls in
<filename>sleep.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>suspend-then-hibernate.target</filename></term>
<listitem>
<para>A special target unit for suspending the system for a period
of time, waking it and putting it into hibernate. This pulls in
<filename>sleep.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>halt.target</filename></term>
<listitem>
<para>A special target unit for shutting down and halting
the system. Note that this target is distinct from
<filename>poweroff.target</filename> in that it generally
really just halts the system rather than powering it
down.</para>
<para>Applications wanting to halt the system should not start this unit
directly, but should instead execute <command>systemctl halt</command>
(possibly with the <option>--no-block</option> option) or call
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<command>org.freedesktop.systemd1.Manager.Halt</command> D-Bus method
directly.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>init.scope</filename></term>
<listitem>
<para>This scope unit is where the system and service manager (PID 1) itself resides. It
is active as long as the system is running.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>initrd.target</filename></term>
<listitem>
<para>This is the default target in the initramfs, similar to <filename>default.target</filename>
in the main system. It is used to mount the real root and transition to it. See
<citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry> for
more discussion.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>initrd-fs.target</filename></term>
<listitem>
<para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
automatically adds dependencies of type
<varname>Before=</varname> to
<filename>sysroot-usr.mount</filename> and all mount points
found in <filename>/etc/fstab</filename> that have
<option>x-initrd.mount</option> and not have
<option>noauto</option> mount options set.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>initrd-root-device.target</filename></term>
<listitem>
<para>A special initrd target unit that is reached when the root filesystem device is available, but before
it has been mounted.
<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
and
<citerefentry><refentrytitle>systemd-gpt-auto-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
automatically setup the appropriate dependencies to make this happen.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>initrd-root-fs.target</filename></term>
<listitem>
<para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
automatically adds dependencies of type
<varname>Before=</varname> to the
<filename>sysroot.mount</filename> unit, which is generated
from the kernel command line.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>kbrequest.target</filename></term>
<listitem>
<para>systemd starts this target whenever Alt+ArrowUp is
pressed on the console. Note that any user with physical access
to the machine will be able to do this, without authentication,
so this should be used carefully.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>kexec.target</filename></term>
<listitem>
<para>A special target unit for shutting down and rebooting
the system via kexec.</para>
<para>Applications wanting to reboot the system should not start this unit
directly, but should instead execute <command>systemctl kexec</command>
(possibly with the <option>--no-block</option> option) or call
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>'s
<command>org.freedesktop.systemd1.Manager.KExec</command> D-Bus method
directly.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>local-fs.target</filename></term>
<listitem>
<para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
automatically adds dependencies of type
<varname>Before=</varname> to all mount units that refer to
local mount points for this target unit. In addition, it
adds dependencies of type <varname>Wants=</varname> to this
target unit for those mounts listed in
<filename>/etc/fstab</filename> that have the
<option>auto</option> mount option set.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>machines.target</filename></term>
<listitem>
<para>A standard target unit for starting all the containers
and other virtual machines. See <filename>systemd-nspawn@.service</filename>
for an example.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>multi-user.target</filename></term>
<listitem>
<para>A special target unit for setting up a multi-user
system (non-graphical). This is pulled in by
<filename>graphical.target</filename>.</para>
<para>Units that are needed for a multi-user system shall
add <varname>Wants=</varname> dependencies for their unit to
this unit during installation. This is best configured via
<varname>WantedBy=multi-user.target</varname> in the unit's
<literal>[Install]</literal> section.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>network-online.target</filename></term>
<listitem>
<para>Units that strictly require a configured network
connection should pull in
<filename>network-online.target</filename> (via a
<varname>Wants=</varname> type dependency) and order
themselves after it. This target unit is intended to pull in
a service that delays further execution until the network is
sufficiently set up. What precisely this requires is left to
the implementation of the network managing service.</para>
<para>Note the distinction between this unit and
<filename>network.target</filename>. This unit is an active
unit (i.e. pulled in by the consumer rather than the
provider of this functionality) and pulls in a service which
possibly adds substantial delays to further execution. In
contrast, <filename>network.target</filename> is a passive
unit (i.e. pulled in by the provider of the functionality,
rather than the consumer) that usually does not delay
execution much. Usually, <filename>network.target</filename>
is part of the boot of most systems, while
<filename>network-online.target</filename> is not, except
when at least one unit requires it. Also see <ulink
url="https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
Services After the Network is up</ulink> for more
information.</para>
<para>All mount units for remote network file systems
automatically pull in this unit, and order themselves after
it. Note that networking daemons that simply provide
functionality to other hosts generally do not need to pull
this in.</para>
<para>systemd automatically adds dependencies of type <varname>Wants=</varname> and
<varname>After=</varname> for this target unit to all SysV init script service units
with an LSB header referring to the <literal>$network</literal> facility.</para>
<para>Note that this unit is only useful during the original system start-up
logic. After the system has completed booting up, it will not track the online state of
the system anymore. Due to this it cannot be used as a network connection monitor
concept, it is purely a one-time system start-up concept.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>paths.target</filename></term>
<listitem>
<para>A special target unit that sets up all path units (see
<citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details) that shall be active after boot.</para>
<para>It is recommended that path units installed by
applications get pulled in via <varname>Wants=</varname>
dependencies from this unit. This is best configured via a
<varname>WantedBy=paths.target</varname> in the path unit's
<literal>[Install]</literal> section.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>poweroff.target</filename></term>
<listitem>
<para>A special target unit for shutting down and powering
off the system.</para>
<para>Applications wanting to power off the system should not start this unit
directly, but should instead execute <command>systemctl poweroff</command>
(possibly with the <option>--no-block</option> option) or call
<citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
<command>org.freedesktop.login1.Manager.PowerOff</command> D-Bus method
directly.</para>
<para><filename>runlevel0.target</filename> is an alias for
this target unit, for compatibility with SysV.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>reboot.target</filename></term>
<listitem>
<para>A special target unit for shutting down and rebooting
the system.</para>
<para>Applications wanting to reboot the system should not start this unit
directly, but should instead execute <command>systemctl reboot</command>
(possibly with the <option>--no-block</option> option) or call
<citerefentry><refentrytitle>systemd-logind</refentrytitle><manvolnum>8</manvolnum></citerefentry>'s
<command>org.freedesktop.login1.Manager.Reboot</command> D-Bus method
directly.</para>
<para><filename>runlevel6.target</filename> is an alias for
this target unit, for compatibility with SysV.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>remote-cryptsetup.target</filename></term>
<listitem>
<para>Similar to <filename>cryptsetup.target</filename>, but for encrypted
devices which are accessed over the network. It is used for
<citerefentry><refentrytitle>crypttab</refentrytitle><manvolnum>8</manvolnum></citerefentry>
entries marked with <option>_netdev</option>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>remote-fs.target</filename></term>
<listitem>
<para>Similar to <filename>local-fs.target</filename>, but
for remote mount points.</para>
<para>systemd automatically adds dependencies of type
<varname>After=</varname> for this target unit to all SysV
init script service units with an LSB header referring to
the <literal>$remote_fs</literal> facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>rescue.target</filename></term>
<listitem>
<para>A special target unit that pulls in the base system (including system mounts) and
spawns a rescue shell. Isolate to this target in order to administer the system in
single-user mode with all file systems mounted but with no services running, except for
the most basic. Compare with <filename>emergency.target</filename>, which is much more
reduced and does not provide the file systems or most basic services. Compare with
<filename>multi-user.target</filename>, this target could be seen as
<filename>single-user.target</filename>.</para>
<para><filename>runlevel1.target</filename> is an alias for this target unit, for
compatibility with SysV.</para>
<para>Use the <literal>systemd.unit=rescue.target</literal> kernel command line option
to boot into this mode. A short alias for this kernel command line option is
<literal>1</literal>, for compatibility with SysV.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>runlevel2.target</filename></term>
<term><filename>runlevel3.target</filename></term>
<term><filename>runlevel4.target</filename></term>
<term><filename>runlevel5.target</filename></term>
<listitem>
<para>These are targets that are called whenever the SysV
compatibility code asks for runlevel 2, 3, 4, 5,
respectively. It is a good idea to make this an alias for
(i.e. symlink to) <filename>graphical.target</filename>
(for runlevel 5) or <filename>multi-user.target</filename>
(the others).</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>shutdown.target</filename></term>
<listitem>
<para>A special target unit that terminates the services on
system shutdown.</para>
<para>Services that shall be terminated on system shutdown
shall add <varname>Conflicts=</varname> and
<varname>Before=</varname> dependencies to this unit for
their service unit, which is implicitly done when
<varname>DefaultDependencies=yes</varname> is set (the
default).</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>sigpwr.target</filename></term>
<listitem>
<para>A special target that is started when systemd receives
the SIGPWR process signal, which is normally sent by the
kernel or UPS daemons when power fails.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>sleep.target</filename></term>
<listitem>
<para>A special target unit that is pulled in by
<filename>suspend.target</filename>,
<filename>hibernate.target</filename> and
<filename>hybrid-sleep.target</filename> and may be used to
hook units into the sleep state logic.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>slices.target</filename></term>
<listitem>
<para>A special target unit that sets up all slice units (see
<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details) that shall always be active after boot. By default the generic
<filename>system.slice</filename> slice unit as well as the root slice unit
<filename>-.slice</filename> are pulled in and ordered before this unit (see
below).</para>
<para>Adding slice units to <filename>slices.target</filename> is generally not
necessary. Instead, when some unit that uses <varname>Slice=</varname> is started, the
specified slice will be started automatically. Adding
<varname>WantedBy=slices.target</varname> lines to the <literal>[Install]</literal>
section should only be done for units that need to be always active. In that case care
needs to be taken to avoid creating a loop through the automatic dependencies on
"parent" slices.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>sockets.target</filename></term>
<listitem>
<para>A special target unit that sets up all socket
units (see
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details) that shall be active after boot.</para>
<para>Services that can be socket-activated shall add
<varname>Wants=</varname> dependencies to this unit for
their socket unit during installation. This is best
configured via a <varname>WantedBy=sockets.target</varname>
in the socket unit's <literal>[Install]</literal>
section.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>suspend.target</filename></term>
<listitem>
<para>A special target unit for suspending the system. This
pulls in <filename>sleep.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>swap.target</filename></term>
<listitem>
<para>Similar to <filename>local-fs.target</filename>, but
for swap partitions and swap files.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>sysinit.target</filename></term>
<listitem>
<para>systemd automatically adds dependencies of the types
<varname>Requires=</varname> and <varname>After=</varname>
for this target unit to all services (except for those with
<varname>DefaultDependencies=no</varname>).</para>
<para>This target pulls in the services required for system
initialization. System services pulled in by this target should
declare <varname>DefaultDependencies=no</varname> and specify
all their dependencies manually, including access to anything
more than a read only root filesystem. For details on the
dependencies of this target, refer to
<citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>syslog.socket</filename></term>
<listitem>
<para>The socket unit syslog implementations should listen
on. All userspace log messages will be made available on
this socket. For more information about syslog integration,
please consult the <ulink
url="https://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog
Interface</ulink> document.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>system-update.target</filename></term>
<term><filename>system-update-pre.target</filename></term>
<term><filename>system-update-cleanup.service</filename></term>
<listitem>
<para>A special target unit that is used for offline system updates.
<citerefentry><refentrytitle>systemd-system-update-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
will redirect the boot process to this target if <filename>/system-update</filename>
exists. For more information see
<citerefentry><refentrytitle>systemd.offline-updates</refentrytitle><manvolnum>7</manvolnum></citerefentry>.
</para>
<para>Updates should happen before the <filename>system-update.target</filename> is
reached, and the services which implement them should cause the machine to reboot. The
main units executing the update should order themselves after
<filename>system-update-pre.target</filename> but not pull it in. Services which want to
run during system updates only, but before the actual system update is executed should
order themselves before this unit and pull it in. As a safety measure, if this does not
happen, and <filename>/system-update</filename> still exists after
<filename>system-update.target</filename> is reached,
<filename>system-update-cleanup.service</filename> will remove this symlink and reboot
the machine.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>timers.target</filename></term>
<listitem>
<para>A special target unit that sets up all timer units
(see
<citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for details) that shall be active after boot.</para>
<para>It is recommended that timer units installed by
applications get pulled in via <varname>Wants=</varname>
dependencies from this unit. This is best configured via
<varname>WantedBy=timers.target</varname> in the timer
unit's <literal>[Install]</literal> section.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>umount.target</filename></term>
<listitem>
<para>A special target unit that unmounts all mount and
automount points on system shutdown.</para>
<para>Mounts that shall be unmounted on system shutdown
shall add Conflicts dependencies to this unit for their
mount unit, which is implicitly done when
<varname>DefaultDependencies=yes</varname> is set (the
default).</para>
</listitem>
</varlistentry>
</variablelist>
</refsect2>
<refsect2>
<title>Special System Units for Devices</title>
<para>Some target units are automatically pulled in as devices of
certain kinds show up in the system. These may be used to
automatically activate various services based on the specific type
of the available hardware.</para>
<variablelist>
<varlistentry>
<term><filename>bluetooth.target</filename></term>
<listitem>
<para>This target is started automatically as soon as a
Bluetooth controller is plugged in or becomes available at
boot.</para>
<para>This may be used to pull in Bluetooth management
daemons dynamically when Bluetooth hardware is found.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>printer.target</filename></term>
<listitem>
<para>This target is started automatically as soon as a
printer is plugged in or becomes available at boot.</para>
<para>This may be used to pull in printer management daemons
dynamically when printer hardware is found.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>smartcard.target</filename></term>
<listitem>
<para>This target is started automatically as soon as a
smartcard controller is plugged in or becomes available at
boot.</para>
<para>This may be used to pull in smartcard management
daemons dynamically when smartcard hardware is found.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>sound.target</filename></term>
<listitem>
<para>This target is started automatically as soon as a
sound card is plugged in or becomes available at
boot.</para>
<para>This may be used to pull in audio management daemons
dynamically when audio hardware is found.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>usb-gadget.target</filename></term>
<listitem>
<para>This target is started automatically as soon as a
USB Device Controller becomes available at boot.</para>
<para>This may be used to pull in usb gadget
dynamically when UDC hardware is found.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect2>
<refsect2>
<title>Special Passive System Units </title>
<para>A number of special system targets are defined that can be
used to properly order boot-up of optional services. These targets
are generally not part of the initial boot transaction, unless
they are explicitly pulled in by one of the implementing services.
Note specifically that these <emphasis>passive</emphasis> target
units are generally not pulled in by the consumer of a service,
but by the provider of the service. This means: a consuming
service should order itself after these targets (as appropriate),
but not pull it in. A providing service should order itself before
these targets (as appropriate) and pull it in (via a
<varname>Wants=</varname> type dependency).</para>
<para>Note that these passive units cannot be started manually,
i.e. <literal>systemctl start time-sync.target</literal> will fail
with an error. They can only be pulled in by dependency. This is
enforced since they exist for ordering purposes only and thus are
not useful as only unit within a transaction.</para>
<variablelist>
<varlistentry>
<term><filename>blockdev@.target</filename></term>
<listitem><para>This template unit may be used to order mount units and other consumers of block
devices against services that synthesize these block devices. This is intended to be used to order
storage services (such as
<citerefentry><refentrytitle>systemd-cryptsetup@.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>)
that allocate and manage a virtual block device against mount units and other consumers of
it. Specifically, the storage services are supposed to be orderd before an instance of
<filename>blockdev@.target</filename>, and the mount unit (or other consuming unit, such as a swap
unit) after it. The ordering is particular relevant during shutdown, as it ensures that the mount
is deactivated first and the service backing the mount only deactivated after that completed. The
<filename>blockdev@.target</filename> instance should be pulled in via a <option>Wants=</option>
dependency of the storage daemon and thus generally not be part of any transaction unless a storage
daemon is used. The instance name for instances of this template unit is supposed to be the
properly escaped bock device node path, e.g. <filename>blockdev@dev-mapper-foobar.target</filename>
for a storage device <filename>/dev/mapper/foobar</filename>.</para></listitem>
</varlistentry>
<varlistentry>
<term><filename>cryptsetup-pre.target</filename></term>
<listitem>
<para>This passive target unit may be pulled in by services
that want to run before any encrypted block device is set
up. All encrypted block devices are set up after this target
has been reached. Since the shutdown order is implicitly the
reverse start-up order between units, this target is
particularly useful to ensure that a service is shut down
only after all encrypted block devices are fully
stopped.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>getty-pre.target</filename></term>
<listitem>
<para>A special passive target unit. Users of this target
are expected to pull it in the boot transaction via
a dependency (e.g. <varname>Wants=</varname>). Order your
unit before this unit if you want to make use of the console
just before <filename>getty</filename> is started.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>local-fs-pre.target</filename></term>
<listitem>
<para>This target unit is
automatically ordered before
all local mount points marked
with <option>auto</option>
(see above). It can be used to
execute certain units before
all local mounts.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>network.target</filename></term>
<listitem>
<para>This unit is supposed to indicate when network
functionality is available, but it is only very weakly
defined what that is supposed to mean, with one exception:
at shutdown, a unit that is ordered after
<filename>network.target</filename> will be stopped before
the network — to whatever level it might be set up then —
is shut down. It is hence useful when writing service files
that require network access on shutdown, which should order
themselves after this target, but not pull it in. Also see
<ulink url="https://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
Services After the Network is up</ulink> for more
information. Also see
<filename>network-online.target</filename> described
above.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>network-pre.target</filename></term>
<listitem>
<para>This passive target unit may be pulled in by services
that want to run before any network is set up, for example
for the purpose of setting up a firewall. All network
management software orders itself after this target, but
does not pull it in.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>nss-lookup.target</filename></term>
<listitem>
<para>A target that should be used as synchronization point for all host/network name
service lookups. Note that this is independent of UNIX user/group name lookups for which
<filename>nss-user-lookup.target</filename> should be used. All services for which the
availability of full host/network name resolution is essential should be ordered after
this target, but not pull it in. systemd automatically adds dependencies of type
<varname>After=</varname> for this target unit to all SysV init script service units
with an LSB header referring to the <literal>$named</literal> facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>nss-user-lookup.target</filename></term>
<listitem>
<para>A target that should be used as synchronization point for all regular UNIX
user/group name service lookups. Note that this is independent of host/network name
lookups for which <filename>nss-lookup.target</filename> should be used. All services
for which the availability of the full user/group database is essential should be
ordered after this target, but not pull it in. All services which provide parts of the
user/group database should be ordered before this target, and pull it in. Note that this
unit is only relevant for regular users and groups — system users and groups are
required to be resolvable during earliest boot already, and hence do not need any
special ordering against this target.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>remote-fs-pre.target</filename></term>
<listitem>
<para>This target unit is automatically ordered before all
mount point units (see above) and cryptsetup devices
marked with the <option>_netdev</option>. It can be used to run
certain units before remote encrypted devices and mounts are established.
Note that this unit is generally not part of the initial
transaction, unless the unit that wants to be ordered before
all remote mounts pulls it in via a
<varname>Wants=</varname> type dependency. If the unit wants
to be pulled in by the first remote mount showing up, it
should use <filename>network-online.target</filename> (see
above).</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>rpcbind.target</filename></term>
<listitem>
<para>The portmapper/rpcbind pulls in this target and orders
itself before it, to indicate its availability. systemd
automatically adds dependencies of type
<varname>After=</varname> for this target unit to all SysV
init script service units with an LSB header referring to
the <literal>$portmap</literal> facility.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>time-set.target</filename></term>
<listitem>
<para>Services responsible for setting the system clock from
a local source (such as a maintained timestamp file or
imprecise real-time clock) should pull in this target and
order themselves before it. Services where approximate time
is desired should be ordered after this unit, but not pull
it in. This target does not provide the accuracy guarantees
of <filename>time-sync.target</filename>.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>time-sync.target</filename></term>
<listitem>
<para>Services responsible for synchronizing the system
clock from a remote source (such as NTP client
implementations) should pull in this target and order
themselves before it. All services where correct time is
essential should be ordered after this unit, but not pull it
in. systemd automatically adds dependencies of type
<varname>After=</varname> for this target unit to all SysV
init script service units with an LSB header referring to
the <literal>$time</literal> facility. </para>
</listitem>
</varlistentry>
</variablelist>
</refsect2>
<refsect2>
<title>Special Slice Units</title>
<para>There are four <literal>.slice</literal> units which form the basis of the hierarchy for
assignment of resources for services, users, and virtual machines or containers. See
<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for details about slice units.</para>
<variablelist>
<varlistentry>
<term><filename>-.slice</filename></term>
<listitem>
<para>The root slice is the root of the slice hierarchy. It usually does not contain
units directly, but may be used to set defaults for the whole tree.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>system.slice</filename></term>
<listitem>
<para>By default, all system services started by
<command>systemd</command> are found in this slice.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>user.slice</filename></term>
<listitem>
<para>By default, all user processes and services started on
behalf of the user, including the per-user systemd instance
are found in this slice. This is pulled in by
<filename>systemd-logind.service</filename></para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>machine.slice</filename></term>
<listitem>
<para>By default, all virtual machines and containers
registered with <command>systemd-machined</command> are
found in this slice. This is pulled in by
<filename>systemd-machined.service</filename></para>
</listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<refsect1>
<title>Units managed by the user's service manager</title>
<refsect2>
<title>Special User Units</title>
<para>When systemd runs as a user instance, the following special
units are available:</para>
<variablelist>
<varlistentry>
<term><filename>default.target</filename></term>
<listitem>
<para>This is the main target of the user session, started by default. Various services that
compose the normal user session should be pulled into this target. In this regard,
<filename>default.target</filename> is similar to <filename>multi-user.target</filename> in the
system instance, but it is a real unit, not an alias.</para>
</listitem>
</varlistentry>
</variablelist>
<para>In addition, the following units are available which have definitions similar to their
system counterparts:
<filename>exit.target</filename>,
<filename>shutdown.target</filename>,
<filename>sockets.target</filename>,
<filename>timers.target</filename>,
<filename>paths.target</filename>,
<filename>bluetooth.target</filename>,
<filename>printer.target</filename>,
<filename>smartcard.target</filename>,
<filename>sound.target</filename>.</para>
</refsect2>
<refsect2>
<title>Special Passive User Units</title>
<variablelist>
<varlistentry>
<term><filename>graphical-session.target</filename></term>
<listitem>
<para>This target is active whenever any graphical session is running. It is used to
stop user services which only apply to a graphical (X, Wayland, etc.) session when the
session is terminated. Such services should have
<literal>PartOf=graphical-session.target</literal> in their <literal>[Unit]</literal>
section. A target for a particular session (e. g.
<filename>gnome-session.target</filename>) starts and stops
<literal>graphical-session.target</literal> with
<literal>BindsTo=graphical-session.target</literal>.</para>
<para>Which services are started by a session target is determined by the
<literal>Wants=</literal> and <literal>Requires=</literal> dependencies. For services
that can be enabled independently, symlinks in <literal>.wants/</literal> and
<literal>.requires/</literal> should be used, see
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.
Those symlinks should either be shipped in packages, or should be added dynamically
after installation, for example using <literal>systemctl add-wants</literal>, see
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
</para>
<example>
<title>Nautilus as part of a GNOME session</title>
<para><literal>gnome-session.target</literal> pulls in Nautilus as top-level service:</para>
<programlisting>[Unit]
Description=User systemd services for GNOME graphical session
Wants=nautilus.service
BindsTo=graphical-session.target</programlisting>
<para><literal>nautilus.service</literal> gets stopped when the session stops:</para>
<programlisting>[Unit]
Description=Render the desktop icons with Nautilus
PartOf=graphical-session.target
[Service]
…</programlisting>
</example>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>graphical-session-pre.target</filename></term>
<listitem>
<para>This target contains services which set up the environment or global configuration
of a graphical session, such as SSH/GPG agents (which need to export an environment
variable into all desktop processes) or migration of obsolete d-conf keys after an OS
upgrade (which needs to happen before starting any process that might use them). This
target must be started before starting a graphical session like
<filename>gnome-session.target</filename>.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect2>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>user@.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
|