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udevadm-settle: add missing brace
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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">
4
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6   This file is part of systemd.
7
8   Copyright 2010 Lennart Poettering
9
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11   under the terms of the GNU Lesser General Public License as published by
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18   Lesser General Public License for more details.
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21   along with systemd; If not, see <http://www.gnu.org/licenses/>.
22 -->
23
24 <refentry id="systemd.special">
25
26         <refentryinfo>
27                 <title>systemd.special</title>
28                 <productname>systemd</productname>
29
30                 <authorgroup>
31                         <author>
32                                 <contrib>Developer</contrib>
33                                 <firstname>Lennart</firstname>
34                                 <surname>Poettering</surname>
35                                 <email>lennart@poettering.net</email>
36                         </author>
37                 </authorgroup>
38         </refentryinfo>
39
40         <refmeta>
41                 <refentrytitle>systemd.special</refentrytitle>
42                 <manvolnum>7</manvolnum>
43         </refmeta>
44
45         <refnamediv>
46                 <refname>systemd.special</refname>
47                 <refpurpose>Special systemd units</refpurpose>
48         </refnamediv>
49
50         <refsynopsisdiv>
51                 <para><filename>basic.target</filename>,
52                 <filename>bluetooth.target</filename>,
53                 <filename>ctrl-alt-del.target</filename>,
54                 <filename>cryptsetup.target</filename>,
55                 <filename>dbus.service</filename>,
56                 <filename>dbus.socket</filename>,
57                 <filename>default.target</filename>,
58                 <filename>display-manager.service</filename>,
59                 <filename>emergency.target</filename>,
60                 <filename>exit.target</filename>,
61                 <filename>final.target</filename>,
62                 <filename>getty.target</filename>,
63                 <filename>graphical.target</filename>,
64                 <filename>halt.target</filename>,
65                 <filename>hibernate.target</filename>,
66                 <filename>hybrid-sleep.target</filename>,
67                 <filename>initrd-fs.target</filename>,
68                 <filename>kbrequest.target</filename>,
69                 <filename>kexec.target</filename>,
70                 <filename>local-fs.target</filename>,
71                 <filename>local-fs-pre.target</filename>,
72                 <filename>multi-user.target</filename>,
73                 <filename>network.target</filename>,
74                 <filename>network-online.target</filename>,
75                 <filename>nss-lookup.target</filename>,
76                 <filename>nss-user-lookup.target</filename>,
77                 <filename>paths.target</filename>,
78                 <filename>poweroff.target</filename>,
79                 <filename>printer.target</filename>,
80                 <filename>reboot.target</filename>,
81                 <filename>remote-fs.target</filename>,
82                 <filename>remote-fs-pre.target</filename>,
83                 <filename>rescue.target</filename>,
84                 <filename>initrd-root-fs.target</filename>,
85                 <filename>rpcbind.target</filename>,
86                 <filename>runlevel2.target</filename>,
87                 <filename>runlevel3.target</filename>,
88                 <filename>runlevel4.target</filename>,
89                 <filename>runlevel5.target</filename>,
90                 <filename>shutdown.target</filename>,
91                 <filename>sigpwr.target</filename>,
92                 <filename>sleep.target</filename>,
93                 <filename>smartcard.target</filename>,
94                 <filename>sockets.target</filename>,
95                 <filename>sound.target</filename>,
96                 <filename>suspend.target</filename>,
97                 <filename>swap.target</filename>,
98                 <filename>sysinit.target</filename>,
99                 <filename>syslog.socket</filename>,
100                 <filename>system-update.target</filename>,
101                 <filename>time-sync.target</filename>,
102                 <filename>timers.target</filename>,
103                 <filename>umount.target</filename>,
104                 <filename>-.slice</filename>,
105                 <filename>system.slice</filename>,
106                 <filename>user.slice</filename>,
107                 <filename>machine.slice</filename></para>
108         </refsynopsisdiv>
109
110         <refsect1>
111                 <title>Description</title>
112
113                 <para>A few units are treated specially by
114                 systemd. They have special internal semantics and
115                 cannot be renamed.</para>
116         </refsect1>
117
118         <refsect1>
119                 <title>Special System Units</title>
120
121                 <variablelist>
122                         <varlistentry>
123                                 <term><filename>basic.target</filename></term>
124                                 <listitem>
125                                         <para>A special target unit
126                                         covering basic boot-up.</para>
127                                         <para>systemd automatically
128                                         adds dependencies of the types
129                                         <varname>Requires=</varname>
130                                         and <varname>After=</varname>
131                                         for this target unit to all
132                                         services (except for those
133                                         with
134                                         <varname>DefaultDependencies=no</varname>).</para>
135
136                                         <para>Usually this should
137                                         pull-in all mount points, swap
138                                         devices, sockets, timers, and
139                                         path units and other basic
140                                         initialization necessary for
141                                         general purpose
142                                         daemons.</para>
143                                 </listitem>
144                         </varlistentry>
145                         <varlistentry>
146                                 <term><filename>ctrl-alt-del.target</filename></term>
147                                 <listitem>
148                                         <para>systemd starts this
149                                         target whenever
150                                         Control+Alt+Del is pressed on
151                                         the console. Usually this
152                                         should be aliased (symlinked)
153                                         to
154                                         <filename>reboot.target</filename>.</para>
155                                 </listitem>
156                         </varlistentry>
157                         <varlistentry>
158                                 <term><filename>cryptsetup.target</filename></term>
159                                 <listitem>
160                                         <para>A target that pulls in
161                                         setup services for all
162                                         encrypted block
163                                         devices.</para>
164                                 </listitem>
165                         </varlistentry>
166                         <varlistentry>
167                                 <term><filename>dbus.service</filename></term>
168                                 <listitem>
169                                         <para>A special unit for the
170                                         D-Bus bus daemon. As soon as
171                                         this service is fully started
172                                         up systemd will connect to it
173                                         and register its
174                                         service.</para>
175                                 </listitem>
176                         </varlistentry>
177                         <varlistentry>
178                                 <term><filename>dbus.socket</filename></term>
179                                 <listitem>
180                                         <para>A special unit for the
181                                         D-Bus system bus socket. All
182                                         units with
183                                         <varname>Type=dbus</varname>
184                                         automatically gain a
185                                         dependency on this
186                                         unit.</para>
187                                 </listitem>
188                         </varlistentry>
189                         <varlistentry>
190                                 <term><filename>default.target</filename></term>
191                                 <listitem>
192                                         <para>The default unit systemd
193                                         starts at bootup. Usually this
194                                         should be aliased (symlinked)
195                                         to
196                                         <filename>multi-user.target</filename>
197                                         or
198                                         <filename>graphical.target</filename>.</para>
199
200                                         <para>The default unit systemd
201                                         starts at bootup can be
202                                         overridden with the
203                                         <varname>systemd.unit=</varname>
204                                         kernel command line option.</para>
205                                 </listitem>
206                         </varlistentry>
207                         <varlistentry>
208                                 <term><filename>display-manager.service</filename></term>
209                                 <listitem>
210                                         <para>The display manager
211                                         service. Usually this should
212                                         be aliased (symlinked) to
213                                         <filename>gdm.service</filename>
214                                         or a similar display manager
215                                         service.</para>
216                                 </listitem>
217                         </varlistentry>
218                         <varlistentry>
219                                 <term><filename>emergency.target</filename></term>
220                                 <listitem>
221                                         <para>A special target unit
222                                         that starts an emergency
223                                         shell on the main
224                                         console. This unit is supposed
225                                         to be used with the kernel
226                                         command line option
227                                         <varname>systemd.unit=</varname>
228                                         and has otherwise little use.
229                                         </para>
230                                 </listitem>
231                         </varlistentry>
232                         <varlistentry>
233                                 <term><filename>final.target</filename></term>
234                                 <listitem>
235                                         <para>A special target unit
236                                         that is used during the
237                                         shutdown logic and may be used
238                                         to pull in late services after
239                                         all normal services are
240                                         already terminated and all
241                                         mounts unmounted.
242                                         </para>
243                                 </listitem>
244                         </varlistentry>
245                         <varlistentry>
246                                 <term><filename>getty.target</filename></term>
247                                 <listitem>
248                                         <para>A special target unit
249                                         that pulls in statically
250                                         configured local TTY
251                                         <filename>getty</filename>
252                                         instances.
253                                         </para>
254                                 </listitem>
255                         </varlistentry>
256                         <varlistentry>
257                                 <term><filename>graphical.target</filename></term>
258                                 <listitem>
259                                         <para>A special target unit
260                                         for setting up a graphical
261                                         login screen. This pulls in
262                                         <filename>multi-user.target</filename>.</para>
263
264                                         <para>Units that are needed
265                                         for graphical logins shall add
266                                         <varname>Wants=</varname>
267                                         dependencies for their unit to
268                                         this unit (or
269                                         <filename>multi-user.target</filename>)
270                                         during installation. This is
271                                         best configured via
272                                         <varname>WantedBy=graphical.target</varname>
273                                         in the unit's
274                                         <literal>[Install]</literal>
275                                         section.</para>
276                                 </listitem>
277                         </varlistentry>
278                         <varlistentry>
279                                 <term><filename>hibernate.target</filename></term>
280                                 <listitem>
281                                         <para>A special target unit
282                                         for hibernating the
283                                         system. This pulls in
284                                         <filename>sleep.target</filename>.</para>
285                                 </listitem>
286                         </varlistentry>
287                         <varlistentry>
288                                 <term><filename>hybrid-sleep.target</filename></term>
289                                 <listitem>
290                                         <para>A special target unit
291                                         for hibernating and suspending the
292                                         system at the same time. This pulls in
293                                         <filename>sleep.target</filename>.</para>
294                                 </listitem>
295                         </varlistentry>
296                         <varlistentry>
297                                 <term><filename>halt.target</filename></term>
298                                 <listitem>
299                                         <para>A special target unit
300                                         for shutting down and halting
301                                         the system. Note that this
302                                         target is distinct from
303                                         <filename>poweroff.target</filename>
304                                         in that it generally really
305                                         just halts the system rather
306                                         than powering it down.</para>
307
308                                         <para>Applications wanting to
309                                         halt the system should start
310                                         this unit.</para>
311                                 </listitem>
312                         </varlistentry>
313                         <varlistentry>
314                                 <term><filename>initrd-fs.target</filename></term>
315                                 <listitem>
316                                         <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
317                                         automatically adds
318                                         dependencies of type
319                                         <varname>Before=</varname> to
320                                         <filename>sysroot-usr.mount</filename>
321                                         and all mount points found in
322                                         <filename>/etc/fstab</filename>
323                                         that have the
324                                         <option>auto</option> and
325                                         <option>x-initrd.mount</option>
326                                         mount options set.
327                                         </para>
328                                 </listitem>
329                         </varlistentry>
330                         <varlistentry>
331                                 <term><filename>kbrequest.target</filename></term>
332                                 <listitem>
333                                         <para>systemd starts this
334                                         target whenever Alt+ArrowUp is
335                                         pressed on the console. This
336                                         is a good candidate to be
337                                         aliased (symlinked) to
338                                         <filename>rescue.target</filename>.</para>
339                                 </listitem>
340                         </varlistentry>
341                         <varlistentry>
342                                 <term><filename>kexec.target</filename></term>
343                                 <listitem>
344                                         <para>A special target unit
345                                         for shutting down and rebooting the system via kexec.</para>
346
347                                         <para>Applications wanting to
348                                         reboot the system with kexec should start
349                                         this unit.</para>
350                                 </listitem>
351                         </varlistentry>
352                         <varlistentry>
353                                 <term><filename>local-fs.target</filename></term>
354                                 <listitem>
355                                         <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
356                                         automatically adds
357                                         dependencies of type
358                                         <varname>Before=</varname> to
359                                         all mount units that refer to
360                                         local mount points for this
361                                         target unit. In addition, it
362                                         adds dependencies of type
363                                         <varname>Wants=</varname> to
364                                         this target unit for those
365                                         mounts listed in
366                                         <filename>/etc/fstab</filename>
367                                         that have the
368                                         <option>auto</option> mount
369                                         option set.</para>
370                                 </listitem>
371                         </varlistentry>
372                         <varlistentry>
373                                 <term><filename>multi-user.target</filename></term>
374                                 <listitem>
375                                         <para>A special target unit
376                                         for setting up a multi-user
377                                         system (non-graphical). This
378                                         is pulled in by
379                                         <filename>graphical.target</filename>.</para>
380
381                                         <para>Units that are needed
382                                         for a multi-user system shall
383                                         add <varname>Wants=</varname>
384                                         dependencies for their unit to
385                                         this unit during
386                                         installation. This is best
387                                         configured via
388                                         <varname>WantedBy=multi-user.target</varname>
389                                         in the unit's
390                                         <literal>[Install]</literal>
391                                         section.</para>
392                                 </listitem>
393                         </varlistentry>
394                         <varlistentry>
395                                 <term><filename>network-online.target</filename></term>
396                                 <listitem>
397                                         <para>Units that strictly
398                                         require a configured network
399                                         connection should pull in
400                                         <filename>network-online.target</filename>
401                                         (via a
402                                         <varname>Wants=</varname> type
403                                         dependency) and order
404                                         themselves after it. This
405                                         target unit is intended to
406                                         pull in a service that delays
407                                         further execution until the
408                                         network is sufficiently set
409                                         up. What precisely this
410                                         requires is left to the
411                                         implementation of the network
412                                         managing service.</para>
413
414                                         <para>Note the distinction
415                                         between this unit and
416                                         <filename>network.target</filename>. This
417                                         unit is an active unit
418                                         (i.e. pulled in by the
419                                         consumer rather than the
420                                         provider of this
421                                         functionality) and pulls in a
422                                         service which possibly adds
423                                         substantial delays to further
424                                         execution. In contrast,
425                                         <filename>network.target</filename>
426                                         is a passive unit (i.e. pulled
427                                         in by the provider of the
428                                         functionality, rather than the
429                                         consumer) that usually does
430                                         not delay execution
431                                         much. Usually,
432                                         <filename>network.target</filename>
433                                         is part of the boot of most
434                                         systems, while
435                                         <filename>network-online.target</filename>
436                                         is not, except when at least
437                                         one unit requires it. Also see
438                                         <ulink
439                                         url="http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
440                                         Services After the Network is
441                                         up</ulink> for more
442                                         information.</para>
443
444                                         <para>All mount units for
445                                         remote network file systems
446                                         automatically pull in this
447                                         unit, and order themselves
448                                         after it. Note that networking
449                                         daemons that simply provide
450                                         functionality to other hosts
451                                         generally do not need to pull
452                                         this in.</para>
453                                         </listitem>
454                         </varlistentry>
455                         <varlistentry>
456                                 <term><filename>paths.target</filename></term>
457                                 <listitem>
458                                         <para>A special target unit
459                                         that sets up all path units
460                                         (see
461                                         <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>
462                                         for details) that shall be
463                                         active after boot.</para>
464
465                                         <para>It is recommended that
466                                         path units installed by
467                                         applications get pulled in via
468                                         <varname>Wants=</varname>
469                                         dependencies from this
470                                         unit. This is best configured
471                                         via a
472                                         <varname>WantedBy=paths.target</varname>
473                                         in the path unit's
474                                         <literal>[Install]</literal>
475                                         section.</para>
476                                 </listitem>
477                         </varlistentry>
478                         <varlistentry>
479                                 <term><filename>poweroff.target</filename></term>
480                                 <listitem>
481                                         <para>A special target unit
482                                         for shutting down and powering off the system.</para>
483
484                                         <para>Applications wanting to
485                                         power off the system should start
486                                         this unit.</para>
487
488                                         <para><filename>runlevel0.target</filename>
489                                         is an alias for this target
490                                         unit, for compatibility with SysV.</para>
491                                 </listitem>
492                         </varlistentry>
493                         <varlistentry>
494                                 <term><filename>reboot.target</filename></term>
495                                 <listitem>
496                                         <para>A special target unit
497                                         for shutting down and rebooting the system.</para>
498
499                                         <para>Applications wanting to
500                                         reboot the system should start
501                                         this unit.</para>
502
503                                         <para><filename>runlevel6.target</filename>
504                                         is an alias for this target
505                                         unit, for compatibility with SysV.</para>
506                                 </listitem>
507                         </varlistentry>
508                         <varlistentry>
509                                 <term><filename>remote-fs.target</filename></term>
510                                 <listitem>
511                                         <para>Similar to
512                                         <filename>local-fs.target</filename>,
513                                         but for remote mount
514                                         points.</para>
515
516                                         <para>systemd automatically
517                                         adds dependencies of type
518                                         <varname>After=</varname> for
519                                         this target unit to all SysV
520                                         init script service units with
521                                         an LSB header referring to the
522                                         <literal>$remote_fs</literal>
523                                         facility.</para>
524                                 </listitem>
525                         </varlistentry>
526                         <varlistentry>
527                                 <term><filename>rescue.target</filename></term>
528                                 <listitem>
529                                         <para>A special target unit
530                                         for setting up the base system
531                                         and a rescue shell.</para>
532
533                                         <para><filename>runlevel1.target</filename>
534                                         is an alias for this target
535                                         unit, for compatibility with SysV.</para>
536                                 </listitem>
537                         </varlistentry>
538                         <varlistentry>
539                                 <term><filename>initrd-root-fs.target</filename></term>
540                                 <listitem>
541                                         <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry>
542                                         automatically adds
543                                         dependencies of type
544                                         <varname>Before=</varname> to
545                                         the
546                                         <filename>sysroot.mount</filename>
547                                         unit, which is generated from
548                                         the kernel command line.
549                                         </para>
550                                 </listitem>
551                         </varlistentry>
552                         <varlistentry>
553                                 <term><filename>runlevel2.target</filename></term>
554                                 <term><filename>runlevel3.target</filename></term>
555                                 <term><filename>runlevel4.target</filename></term>
556                                 <term><filename>runlevel5.target</filename></term>
557                                 <listitem>
558                                         <para>These are targets that
559                                         are called whenever the SysV
560                                         compatibility code asks for
561                                         runlevel 2, 3, 4, 5,
562                                         respectively. It is a good
563                                         idea to make this an alias for
564                                         (i.e. symlink to)
565                                         <filename>multi-user.target</filename>
566                                         (for runlevel 2) or
567                                         <filename>graphical.target</filename>
568                                         (the others).</para>
569                                 </listitem>
570                         </varlistentry>
571                         <varlistentry>
572                                 <term><filename>shutdown.target</filename></term>
573                                 <listitem>
574                                         <para>A special target unit
575                                         that terminates the services
576                                         on system shutdown.</para>
577
578                                         <para>Services that shall be
579                                         terminated on system shutdown
580                                         shall add <varname>Conflicts=</varname>
581                                         dependencies to this unit for
582                                         their service unit, which is
583                                         implicitly done when
584                                         <varname>DefaultDependencies=yes</varname>
585                                         is set (the default).</para>
586                                 </listitem>
587                         </varlistentry>
588                         <varlistentry>
589                                 <term><filename>sigpwr.target</filename></term>
590                                 <listitem>
591                                         <para>A special target that is
592                                         started when systemd receives
593                                         the SIGPWR process signal,
594                                         which is normally sent by the
595                                         kernel or UPS daemons when
596                                         power fails.</para>
597                                 </listitem>
598                         </varlistentry>
599                         <varlistentry>
600                                 <term><filename>sleep.target</filename></term>
601                                 <listitem>
602                                         <para>A special target unit
603                                         that is pulled in by
604                                         <filename>suspend.target</filename>,
605                                         <filename>hibernate.target</filename>
606                                         and
607                                         <filename>hybrid-sleep.target</filename>
608                                         and may be used to hook units
609                                         into the sleep state
610                                         logic.</para>
611                                 </listitem>
612                         </varlistentry>
613                         <varlistentry>
614                                 <term><filename>sockets.target</filename></term>
615                                 <listitem>
616                                         <para>A special target unit
617                                         that sets up all socket
618                                         units.(see
619                                         <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>
620                                         for details) that shall be
621                                         active after boot.</para>
622
623                                         <para>Services that can be
624                                         socket-activated shall add
625                                         <varname>Wants=</varname>
626                                         dependencies to this unit for
627                                         their socket unit during
628                                         installation. This is best
629                                         configured via a
630                                         <varname>WantedBy=sockets.target</varname>
631                                         in the socket unit's
632                                         <literal>[Install]</literal>
633                                         section.</para>
634                                 </listitem>
635                         </varlistentry>
636                         <varlistentry>
637                                 <term><filename>suspend.target</filename></term>
638                                 <listitem>
639                                         <para>A special target unit
640                                         for suspending the
641                                         system. This pulls in
642                                         <filename>sleep.target</filename>.</para>
643                                 </listitem>
644                         </varlistentry>
645                         <varlistentry>
646                                 <term><filename>swap.target</filename></term>
647                                 <listitem>
648                                         <para>Similar to
649                                         <filename>local-fs.target</filename>, but for swap
650                                         partitions and swap
651                                         files.</para>
652                                 </listitem>
653                         </varlistentry>
654                         <varlistentry>
655                                 <term><filename>sysinit.target</filename></term>
656                                 <listitem>
657                                         <para>A special target unit
658                                         covering early boot-up scripts.</para>
659                                 </listitem>
660                         </varlistentry>
661                         <varlistentry>
662                                 <term><filename>syslog.socket</filename></term>
663                                 <listitem>
664                                         <para>The socket unit
665                                         syslog implementations should
666                                         listen on. All userspace log
667                                         messages will be made
668                                         available on this socket. For
669                                         more information about syslog
670                                         integration, please consult
671                                         the <ulink
672                                         url="http://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog
673                                         Interface</ulink>
674                                         document.</para>
675                                 </listitem>
676                         </varlistentry>
677                         <varlistentry>
678                                 <term><filename>system-update.target</filename></term>
679                                 <listitem>
680                                         <para>A special target unit
681                                         that is used for off-line
682                                         system updates.
683                                         <citerefentry><refentrytitle>systemd-system-update-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
684                                         will redirect the boot process
685                                         to this target if
686                                         <filename>/system-update</filename>
687                                         exists. For more information
688                                         see the <ulink
689                                         url="http://freedesktop.org/wiki/Software/systemd/SystemUpdates">System
690                                         Updates
691                                         Specification</ulink>.</para>
692                                 </listitem>
693                         </varlistentry>
694                         <varlistentry>
695                                 <term><filename>timers.target</filename></term>
696                                 <listitem>
697                                         <para>A special target unit
698                                         that sets up all timer
699                                         units (see
700                                         <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>
701                                         for details) that shall be
702                                         active after boot.</para>
703
704                                         <para>It is recommended that
705                                         timer units installed by
706                                         applications get pulled in via
707                                         <varname>Wants=</varname>
708                                         dependencies from this
709                                         unit. This is best configured
710                                         via
711                                         <varname>WantedBy=timers.target</varname>
712                                         in the timer unit's
713                                         <literal>[Install]</literal>
714                                         section.</para>
715                                 </listitem>
716                         </varlistentry>
717                         <varlistentry>
718                                 <term><filename>umount.target</filename></term>
719                                 <listitem>
720                                         <para>A special target unit
721                                         that umounts all mount and
722                                         automount points on system
723                                         shutdown.</para>
724
725                                         <para>Mounts that shall be
726                                         unmounted on system shutdown
727                                         shall add Conflicts
728                                         dependencies to this unit for
729                                         their mount unit, which is
730                                         implicitly done when
731                                         <varname>DefaultDependencies=yes</varname>
732                                         is set (the default).</para>
733                                 </listitem>
734                         </varlistentry>
735
736                 </variablelist>
737         </refsect1>
738
739         <refsect1>
740                 <title>Special System Units for Devices</title>
741
742                 <para>Some target units are automatically pulled in as
743                 devices of certain kinds show up in the system. These
744                 may be used to automatically activate various services
745                 based on the specific type of the available
746                 hardware.</para>
747
748                 <variablelist>
749                         <varlistentry>
750                                 <term><filename>bluetooth.target</filename></term>
751                                 <listitem>
752                                         <para>This target is started
753                                         automatically as soon as a
754                                         Bluetooth controller is
755                                         plugged in or becomes
756                                         available at boot.</para>
757
758                                         <para>This may be used to pull
759                                         in Bluetooth management
760                                         daemons dynamically when
761                                         Bluetooth hardware is
762                                         found.</para>
763                                 </listitem>
764                         </varlistentry>
765                         <varlistentry>
766                                 <term><filename>printer.target</filename></term>
767                                 <listitem>
768                                         <para>This target is started
769                                         automatically as soon as a
770                                         printer is plugged in or
771                                         becomes available at
772                                         boot.</para>
773
774                                         <para>This may be used to pull
775                                         in printer management
776                                         daemons dynamically when
777                                         printer hardware is
778                                         found.</para>
779                                 </listitem>
780                         </varlistentry>
781                         <varlistentry>
782                                 <term><filename>smartcard.target</filename></term>
783                                 <listitem>
784                                         <para>This target is started
785                                         automatically as soon as a
786                                         smartcard controller is
787                                         plugged in or becomes
788                                         available at boot.</para>
789
790                                         <para>This may be used to pull
791                                         in smartcard management
792                                         daemons dynamically when
793                                         smartcard hardware is
794                                         found.</para>
795                                 </listitem>
796                         </varlistentry>
797                         <varlistentry>
798                                 <term><filename>sound.target</filename></term>
799                                 <listitem>
800                                         <para>This target is started
801                                         automatically as soon as a
802                                         sound card is plugged in or
803                                         becomes available at
804                                         boot.</para>
805
806                                         <para>This may be used to pull
807                                         in audio management daemons
808                                         dynamically when audio
809                                         hardware is found.</para>
810                                 </listitem>
811                         </varlistentry>
812                 </variablelist>
813         </refsect1>
814
815         <refsect1>
816                 <title>Special Passive System Units </title>
817
818                 <para>A number of special system targets are defined
819                 that can be used to properly order boot-up of optional
820                 services. These targets are generally not part of the
821                 initial boot transaction, unless they are explicitly
822                 pulled in by one of the implementing services. Note
823                 specifically, that these <emphasis>passive</emphasis>
824                 target units are generally not pulled in by the
825                 consumer of a service, but by the provider of the
826                 service. This means: a consuming service should order
827                 itself after these targets (as appropriate), but not
828                 pull it in. A providing service should order itself
829                 before these targets (as appropriate) and pull it in
830                 (via a <varname>Wants=</varname> type
831                 dependency).</para>
832
833                 <para>Note that these passive units cannot be started
834                 manually, i.e. <literal>systemctl start
835                 time-sync.target</literal> will fail with an
836                 error. They can only be pulled in by dependency. This
837                 is enforced since they exist for ordering purposes
838                 only and thus are not useful as only unit within a
839                 transaction.</para>
840
841                 <variablelist>
842                         <varlistentry>
843                                 <term><filename>local-fs-pre.target</filename></term>
844                                 <listitem>
845                                         <para>This target unit is
846                                         automatically ordered before
847                                         all local mount points marked
848                                         with <option>auto</option>
849                                         (see above). It can be used to
850                                         execute certain units before
851                                         all local mounts.</para>
852                                 </listitem>
853                         </varlistentry>
854                         <varlistentry>
855                                 <term><filename>network.target</filename></term>
856                                 <listitem>
857                                         <para>This unit is supposed to
858                                         indicate when network
859                                         functionality is available,
860                                         but it is only very weakly
861                                         defined what that is supposed
862                                         to mean, with one exception:
863                                         at shutdown, a unit that is
864                                         ordered after
865                                         <filename>network.target</filename>
866                                         will be stopped before the
867                                         network -- to whatever level
868                                         it might be set up then -- is
869                                         shut down. Also see <ulink
870                                         url="http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running
871                                         Services After the Network is
872                                         up</ulink> for more
873                                         information. Also see
874                                         <filename>network-online.target</filename>
875                                         described above.</para>
876
877                                         <para>systemd automatically
878                                         adds dependencies of type
879                                         <varname>After=</varname> for
880                                         this target unit to all SysV
881                                         init script service units with
882                                         an LSB header referring to the
883                                         <literal>$network</literal>
884                                         facility.</para>
885
886                                 </listitem>
887                         </varlistentry>
888                         <varlistentry>
889                                 <term><filename>nss-lookup.target</filename></term>
890                                 <listitem>
891                                         <para>A target that should be
892                                         used as synchronization point
893                                         for all host/network name
894                                         service lookups. Note that
895                                         this is independent of
896                                         user/group name lookups for
897                                         which
898                                         <filename>nss-user-lookup.target</filename>
899                                         should be used. systemd
900                                         automatically adds
901                                         dependencies of type
902                                         <varname>After=</varname> for
903                                         this target unit to all SysV
904                                         init script service units with
905                                         an LSB header referring to the
906                                         <literal>$named</literal>
907                                         facility.</para>
908                                 </listitem>
909                         </varlistentry>
910                         <varlistentry>
911                                 <term><filename>nss-user-lookup.target</filename></term>
912                                 <listitem>
913                                         <para>A target that should be
914                                         used as synchronization point
915                                         for all user/group name
916                                         service lookups. Note that
917                                         this is independent of
918                                         host/network name lookups for
919                                         which
920                                         <filename>nss-lookup.target</filename>
921                                         should be used. </para>
922                                 </listitem>
923                         </varlistentry>
924                         <varlistentry>
925                                 <term><filename>remote-fs-pre.target</filename></term>
926                                 <listitem>
927                                         <para>This target unit is
928                                         automatically ordered before
929                                         all remote mount point units
930                                         (see above). It can be used to
931                                         run certain units before the
932                                         remote mounts are
933                                         established. Note that this
934                                         unit is generally not part of
935                                         the initial transaction,
936                                         unless the unit that wants to
937                                         be ordered before all remote
938                                         mounts pulls it in via a
939                                         <varname>Wants=</varname> type
940                                         dependency. If the unit wants
941                                         to be pulled in by the first
942                                         remote mount showing up, it
943                                         should use
944                                         <filename>network-online.target</filename>
945                                         (see above).</para>
946
947                                         <para>Again, this target unit
948                                         is <emphasis>not</emphasis>
949                                         suitable for pulling in other
950                                         units, it is only useful for
951                                         ordering.</para>
952                                 </listitem>
953                         </varlistentry>
954                         <varlistentry>
955                                 <term><filename>rpcbind.target</filename></term>
956                                 <listitem>
957                                         <para>systemd automatically
958                                         adds dependencies of type
959                                         <varname>After=</varname> for
960                                         this target unit to all SysV
961                                         init script service units with
962                                         an LSB header referring to the
963                                         <literal>$portmap</literal>
964                                         facility.</para>
965                                 </listitem>
966                         </varlistentry>
967                         <varlistentry>
968                                 <term><filename>time-sync.target</filename></term>
969                                 <listitem>
970                                         <para>systemd automatically
971                                         adds dependencies of type
972                                         <varname>After=</varname> for
973                                         this target unit to all SysV
974                                         init script service units with
975                                         an LSB header referring to the
976                                         <literal>$time</literal>
977                                         facility.</para>
978                                 </listitem>
979                         </varlistentry>
980                 </variablelist>
981         </refsect1>
982
983         <refsect1>
984                 <title>Special User Units</title>
985
986                 <para>When systemd runs as a user instance, the
987                 following special units are available, which have
988                 similar definitions as their system counterparts:
989                 <filename>default.target</filename>,
990                 <filename>shutdown.target</filename>,
991                 <filename>sockets.target</filename>,
992                 <filename>timers.target</filename>,
993                 <filename>paths.target</filename>,
994                 <filename>bluetooth.target</filename>,
995                 <filename>printer.target</filename>,
996                 <filename>smartcard.target</filename>,
997                 <filename>sound.target</filename>.</para>
998
999                 <para>In addition the following special unit is
1000                 understood only when systemd runs as service instance:</para>
1001
1002                 <variablelist>
1003                         <varlistentry>
1004                                 <term><filename>exit.target</filename></term>
1005                                 <listitem>
1006                                         <para>A special service unit
1007                                         for shutting down the
1008                                         user service manager.</para>
1009
1010                                         <para>Applications wanting to
1011                                         terminate the user service
1012                                         manager should start this
1013                                         unit. If systemd receives
1014                                         <constant>SIGTERM</constant> or <constant>SIGINT</constant> when running
1015                                         as user service daemon, it will
1016                                         start this unit.</para>
1017
1018                                         <para>Normally, this pulls in
1019                                         <filename>shutdown.target</filename>
1020                                         which in turn should be
1021                                         conflicted by all units that
1022                                         want to be shut down on
1023                                         user service manager exit.</para>
1024                                 </listitem>
1025                         </varlistentry>
1026                 </variablelist>
1027         </refsect1>
1028
1029         <refsect1>
1030                 <title>Special Slice Units</title>
1031
1032                 <para>There are four <literal>.slice</literal> units
1033                 which form the basis of the hierarchy for assignment
1034                 of resources for services, users, and virtual machines
1035                 or containers.</para>
1036
1037                 <variablelist>
1038                         <varlistentry>
1039                                 <term><filename>-.slice</filename></term>
1040                                 <listitem>
1041                                         <para>The root slice is the
1042                                         root of the hierarchy. It
1043                                         usually does not contain units
1044                                         directly, but may be used to
1045                                         set defaults for the whole
1046                                         tree.</para>
1047                                 </listitem>
1048                         </varlistentry>
1049
1050                         <varlistentry>
1051                                 <term><filename>system.slice</filename></term>
1052                                 <listitem>
1053                                         <para>By default, all services
1054                                         services started by
1055                                         <command>systemd</command> are
1056                                         found in this slice.</para>
1057                                 </listitem>
1058                         </varlistentry>
1059
1060                         <varlistentry>
1061                                 <term><filename>user.slice</filename></term>
1062                                 <listitem>
1063                                         <para>By default, all user
1064                                         processes and services started
1065                                         on behalf of the user,
1066                                         including the per-user systemd
1067                                         instance are found in this
1068                                         slice.</para>
1069                                 </listitem>
1070                         </varlistentry>
1071
1072                         <varlistentry>
1073                                 <term><filename>machine.slice</filename></term>
1074                                 <listitem>
1075                                         <para>By defalt, all virtual
1076                                         machines and containers
1077                                         registered with
1078                                         <command>systemd-machined</command>
1079                                         are found in this slice.
1080                                         </para>
1081                                 </listitem>
1082                         </varlistentry>
1083                 </variablelist>
1084         </refsect1>
1085
1086         <refsect1>
1087                   <title>See Also</title>
1088                   <para>
1089                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
1090                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1091                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1092                           <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1093                           <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1094                           <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
1095                           <citerefentry><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
1096                           <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
1097                   </para>
1098         </refsect1>
1099
1100 </refentry>