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1 | <?xml version='1.0'?> <!--*-nxml-*--> |
2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" | |
798d3a52 | 3 | "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> |
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4 | |
5 | <!-- | |
6 | This file is part of systemd. | |
7 | ||
8 | Copyright 2010 Lennart Poettering | |
9 | ||
10 | systemd is free software; you can redistribute it and/or modify it | |
5430f7f2 LP |
11 | under the terms of the GNU Lesser General Public License as published by |
12 | the Free Software Foundation; either version 2.1 of the License, or | |
9f235308 LP |
13 | (at your option) any later version. |
14 | ||
15 | systemd is distributed in the hope that it will be useful, but | |
16 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
17 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
5430f7f2 | 18 | Lesser General Public License for more details. |
9f235308 | 19 | |
5430f7f2 | 20 | You should have received a copy of the GNU Lesser General Public License |
9f235308 LP |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
22 | --> | |
23 | ||
24 | <refentry id="systemd.special"> | |
25 | ||
798d3a52 ZJS |
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>cryptsetup-pre.target</filename>, | |
56 | <filename>dbus.service</filename>, | |
57 | <filename>dbus.socket</filename>, | |
58 | <filename>default.target</filename>, | |
59 | <filename>display-manager.service</filename>, | |
60 | <filename>emergency.target</filename>, | |
61 | <filename>exit.target</filename>, | |
62 | <filename>final.target</filename>, | |
63 | <filename>getty.target</filename>, | |
64 | <filename>graphical.target</filename>, | |
65 | <filename>halt.target</filename>, | |
66 | <filename>hibernate.target</filename>, | |
67 | <filename>hybrid-sleep.target</filename>, | |
68 | <filename>initrd-fs.target</filename>, | |
69 | <filename>kbrequest.target</filename>, | |
70 | <filename>kexec.target</filename>, | |
71 | <filename>local-fs.target</filename>, | |
72 | <filename>local-fs-pre.target</filename>, | |
73 | <filename>multi-user.target</filename>, | |
74 | <filename>network.target</filename>, | |
75 | <filename>network-online.target</filename>, | |
76 | <filename>network-pre.target</filename>, | |
77 | <filename>nss-lookup.target</filename>, | |
78 | <filename>nss-user-lookup.target</filename>, | |
79 | <filename>paths.target</filename>, | |
80 | <filename>poweroff.target</filename>, | |
81 | <filename>printer.target</filename>, | |
82 | <filename>reboot.target</filename>, | |
83 | <filename>remote-fs.target</filename>, | |
84 | <filename>remote-fs-pre.target</filename>, | |
85 | <filename>rescue.target</filename>, | |
86 | <filename>initrd-root-fs.target</filename>, | |
87 | <filename>rpcbind.target</filename>, | |
88 | <filename>runlevel2.target</filename>, | |
89 | <filename>runlevel3.target</filename>, | |
90 | <filename>runlevel4.target</filename>, | |
91 | <filename>runlevel5.target</filename>, | |
92 | <filename>shutdown.target</filename>, | |
93 | <filename>sigpwr.target</filename>, | |
94 | <filename>sleep.target</filename>, | |
95 | <filename>smartcard.target</filename>, | |
96 | <filename>sockets.target</filename>, | |
97 | <filename>sound.target</filename>, | |
98 | <filename>suspend.target</filename>, | |
99 | <filename>swap.target</filename>, | |
100 | <filename>sysinit.target</filename>, | |
101 | <filename>syslog.socket</filename>, | |
102 | <filename>system-update.target</filename>, | |
103 | <filename>time-sync.target</filename>, | |
104 | <filename>timers.target</filename>, | |
105 | <filename>umount.target</filename>, | |
106 | <filename>-.slice</filename>, | |
107 | <filename>system.slice</filename>, | |
108 | <filename>user.slice</filename>, | |
109 | <filename>machine.slice</filename></para> | |
110 | </refsynopsisdiv> | |
111 | ||
112 | <refsect1> | |
113 | <title>Description</title> | |
114 | ||
115 | <para>A few units are treated specially by systemd. They have | |
116 | special internal semantics and cannot be renamed.</para> | |
117 | </refsect1> | |
118 | ||
119 | <refsect1> | |
120 | <title>Special System Units</title> | |
121 | ||
122 | <variablelist> | |
123 | <varlistentry> | |
124 | <term><filename>basic.target</filename></term> | |
125 | <listitem> | |
126 | <para>A special target unit covering basic boot-up.</para> | |
127 | ||
128 | <para>systemd automatically adds dependencies of the types | |
129 | <varname>Requires=</varname> and <varname>After=</varname> | |
130 | for this target unit to all services (except for those with | |
131 | <varname>DefaultDependencies=no</varname>).</para> | |
132 | ||
133 | <para>Usually this should pull-in all mount points, swap | |
134 | devices, sockets, timers, and path units and other basic | |
135 | initialization necessary for general purpose daemons.</para> | |
136 | </listitem> | |
137 | </varlistentry> | |
138 | <varlistentry> | |
139 | <term><filename>ctrl-alt-del.target</filename></term> | |
140 | <listitem> | |
141 | <para>systemd starts this target whenever Control+Alt+Del is | |
142 | pressed on the console. Usually this should be aliased | |
143 | (symlinked) to <filename>reboot.target</filename>.</para> | |
144 | </listitem> | |
145 | </varlistentry> | |
146 | <varlistentry> | |
147 | <term><filename>cryptsetup.target</filename></term> | |
148 | <listitem> | |
149 | <para>A target that pulls in setup services for all | |
150 | encrypted block devices.</para> | |
151 | </listitem> | |
152 | </varlistentry> | |
153 | <varlistentry> | |
154 | <term><filename>dbus.service</filename></term> | |
155 | <listitem> | |
156 | <para>A special unit for the D-Bus bus daemon. As soon as | |
157 | this service is fully started up systemd will connect to it | |
158 | and register its service.</para> | |
159 | </listitem> | |
160 | </varlistentry> | |
161 | <varlistentry> | |
162 | <term><filename>dbus.socket</filename></term> | |
163 | <listitem> | |
164 | <para>A special unit for the D-Bus system bus socket. All | |
165 | units with <varname>Type=dbus</varname> automatically gain a | |
166 | dependency on this unit.</para> | |
167 | </listitem> | |
168 | </varlistentry> | |
169 | <varlistentry> | |
170 | <term><filename>default.target</filename></term> | |
171 | <listitem> | |
172 | <para>The default unit systemd starts at bootup. Usually | |
173 | this should be aliased (symlinked) to | |
174 | <filename>multi-user.target</filename> or | |
175 | <filename>graphical.target</filename>.</para> | |
176 | ||
177 | <para>The default unit systemd starts at bootup can be | |
178 | overridden with the <varname>systemd.unit=</varname> kernel | |
179 | command line option.</para> | |
180 | </listitem> | |
181 | </varlistentry> | |
182 | <varlistentry> | |
183 | <term><filename>display-manager.service</filename></term> | |
184 | <listitem> | |
185 | <para>The display manager service. Usually this should be | |
186 | aliased (symlinked) to <filename>gdm.service</filename> or a | |
187 | similar display manager service.</para> | |
188 | </listitem> | |
189 | </varlistentry> | |
190 | <varlistentry> | |
191 | <term><filename>emergency.target</filename></term> | |
192 | <listitem> | |
193 | <para>A special target unit that starts an emergency shell | |
194 | on the main console. This unit is supposed to be used with | |
195 | the kernel command line option | |
196 | <varname>systemd.unit=</varname> and has otherwise little | |
197 | use. | |
198 | </para> | |
199 | </listitem> | |
200 | </varlistentry> | |
201 | <varlistentry> | |
202 | <term><filename>final.target</filename></term> | |
203 | <listitem> | |
204 | <para>A special target unit that is used during the shutdown | |
205 | logic and may be used to pull in late services after all | |
206 | normal services are already terminated and all mounts | |
207 | unmounted. | |
208 | </para> | |
209 | </listitem> | |
210 | </varlistentry> | |
211 | <varlistentry> | |
212 | <term><filename>getty.target</filename></term> | |
213 | <listitem> | |
214 | <para>A special target unit that pulls in statically | |
215 | configured local TTY <filename>getty</filename> instances. | |
216 | </para> | |
217 | </listitem> | |
218 | </varlistentry> | |
219 | <varlistentry> | |
220 | <term><filename>graphical.target</filename></term> | |
221 | <listitem> | |
222 | <para>A special target unit for setting up a graphical login | |
223 | screen. This pulls in | |
224 | <filename>multi-user.target</filename>.</para> | |
225 | ||
226 | <para>Units that are needed for graphical logins shall add | |
227 | <varname>Wants=</varname> dependencies for their unit to | |
228 | this unit (or <filename>multi-user.target</filename>) during | |
229 | installation. This is best configured via | |
230 | <varname>WantedBy=graphical.target</varname> in the unit's | |
231 | <literal>[Install]</literal> section.</para> | |
232 | </listitem> | |
233 | </varlistentry> | |
234 | <varlistentry> | |
235 | <term><filename>hibernate.target</filename></term> | |
236 | <listitem> | |
237 | <para>A special target unit for hibernating the system. This | |
238 | pulls in <filename>sleep.target</filename>.</para> | |
239 | </listitem> | |
240 | </varlistentry> | |
241 | <varlistentry> | |
242 | <term><filename>hybrid-sleep.target</filename></term> | |
243 | <listitem> | |
244 | <para>A special target unit for hibernating and suspending | |
245 | the system at the same time. This pulls in | |
246 | <filename>sleep.target</filename>.</para> | |
247 | </listitem> | |
248 | </varlistentry> | |
249 | <varlistentry> | |
250 | <term><filename>halt.target</filename></term> | |
251 | <listitem> | |
252 | <para>A special target unit for shutting down and halting | |
253 | the system. Note that this target is distinct from | |
254 | <filename>poweroff.target</filename> in that it generally | |
255 | really just halts the system rather than powering it | |
256 | down.</para> | |
257 | ||
258 | <para>Applications wanting to halt the system should start | |
259 | this unit.</para> | |
260 | </listitem> | |
261 | </varlistentry> | |
262 | <varlistentry> | |
263 | <term><filename>initrd-fs.target</filename></term> | |
264 | <listitem> | |
265 | <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
266 | automatically adds dependencies of type | |
267 | <varname>Before=</varname> to | |
268 | <filename>sysroot-usr.mount</filename> and all mount points | |
269 | found in <filename>/etc/fstab</filename> that have | |
270 | <option>x-initrd.mount</option> and not have | |
271 | <option>noauto</option> mount options set.</para> | |
272 | </listitem> | |
273 | </varlistentry> | |
274 | <varlistentry> | |
275 | <term><filename>kbrequest.target</filename></term> | |
276 | <listitem> | |
277 | <para>systemd starts this target whenever Alt+ArrowUp is | |
278 | pressed on the console. This is a good candidate to be | |
279 | aliased (symlinked) to | |
280 | <filename>rescue.target</filename>.</para> | |
281 | </listitem> | |
282 | </varlistentry> | |
283 | <varlistentry> | |
284 | <term><filename>kexec.target</filename></term> | |
285 | <listitem> | |
286 | <para>A special target unit for shutting down and rebooting | |
287 | the system via kexec.</para> | |
288 | ||
289 | <para>Applications wanting to reboot the system with kexec | |
290 | should start this unit.</para> | |
291 | </listitem> | |
292 | </varlistentry> | |
293 | <varlistentry> | |
294 | <term><filename>local-fs.target</filename></term> | |
295 | <listitem> | |
296 | <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
297 | automatically adds dependencies of type | |
298 | <varname>Before=</varname> to all mount units that refer to | |
299 | local mount points for this target unit. In addition, it | |
300 | adds dependencies of type <varname>Wants=</varname> to this | |
301 | target unit for those mounts listed in | |
302 | <filename>/etc/fstab</filename> that have the | |
303 | <option>auto</option> mount option set.</para> | |
304 | </listitem> | |
305 | </varlistentry> | |
306 | <varlistentry> | |
307 | <term><filename>multi-user.target</filename></term> | |
308 | <listitem> | |
309 | <para>A special target unit for setting up a multi-user | |
310 | system (non-graphical). This is pulled in by | |
311 | <filename>graphical.target</filename>.</para> | |
312 | ||
313 | <para>Units that are needed for a multi-user system shall | |
314 | add <varname>Wants=</varname> dependencies for their unit to | |
315 | this unit during installation. This is best configured via | |
316 | <varname>WantedBy=multi-user.target</varname> in the unit's | |
317 | <literal>[Install]</literal> section.</para> | |
318 | </listitem> | |
319 | </varlistentry> | |
320 | <varlistentry> | |
321 | <term><filename>network-online.target</filename></term> | |
322 | <listitem> | |
323 | <para>Units that strictly require a configured network | |
324 | connection should pull in | |
325 | <filename>network-online.target</filename> (via a | |
326 | <varname>Wants=</varname> type dependency) and order | |
327 | themselves after it. This target unit is intended to pull in | |
328 | a service that delays further execution until the network is | |
329 | sufficiently set up. What precisely this requires is left to | |
330 | the implementation of the network managing service.</para> | |
331 | ||
332 | <para>Note the distinction between this unit and | |
333 | <filename>network.target</filename>. This unit is an active | |
334 | unit (i.e. pulled in by the consumer rather than the | |
335 | provider of this functionality) and pulls in a service which | |
336 | possibly adds substantial delays to further execution. In | |
337 | contrast, <filename>network.target</filename> is a passive | |
338 | unit (i.e. pulled in by the provider of the functionality, | |
339 | rather than the consumer) that usually does not delay | |
340 | execution much. Usually, <filename>network.target</filename> | |
341 | is part of the boot of most systems, while | |
342 | <filename>network-online.target</filename> is not, except | |
343 | when at least one unit requires it. Also see <ulink | |
344 | url="http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running | |
345 | Services After the Network is up</ulink> for more | |
346 | information.</para> | |
347 | ||
348 | <para>All mount units for remote network file systems | |
349 | automatically pull in this unit, and order themselves after | |
350 | it. Note that networking daemons that simply provide | |
351 | functionality to other hosts generally do not need to pull | |
352 | this in.</para> | |
353 | </listitem> | |
354 | </varlistentry> | |
355 | <varlistentry> | |
356 | <term><filename>paths.target</filename></term> | |
357 | <listitem> | |
358 | <para>A special target unit that sets up all path units (see | |
359 | <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
360 | for details) that shall be active after boot.</para> | |
361 | ||
362 | <para>It is recommended that path units installed by | |
363 | applications get pulled in via <varname>Wants=</varname> | |
364 | dependencies from this unit. This is best configured via a | |
365 | <varname>WantedBy=paths.target</varname> in the path unit's | |
366 | <literal>[Install]</literal> section.</para> | |
367 | </listitem> | |
368 | </varlistentry> | |
369 | <varlistentry> | |
370 | <term><filename>poweroff.target</filename></term> | |
371 | <listitem> | |
372 | <para>A special target unit for shutting down and powering | |
373 | off the system.</para> | |
374 | ||
375 | <para>Applications wanting to power off the system should | |
376 | start this unit.</para> | |
377 | ||
378 | <para><filename>runlevel0.target</filename> is an alias for | |
379 | this target unit, for compatibility with SysV.</para> | |
380 | </listitem> | |
381 | </varlistentry> | |
382 | <varlistentry> | |
383 | <term><filename>reboot.target</filename></term> | |
384 | <listitem> | |
385 | <para>A special target unit for shutting down and rebooting | |
386 | the system.</para> | |
387 | ||
388 | <para>Applications wanting to reboot the system should start | |
389 | this unit.</para> | |
390 | ||
391 | <para><filename>runlevel6.target</filename> is an alias for | |
392 | this target unit, for compatibility with SysV.</para> | |
393 | </listitem> | |
394 | </varlistentry> | |
395 | <varlistentry> | |
396 | <term><filename>remote-fs.target</filename></term> | |
397 | <listitem> | |
398 | <para>Similar to <filename>local-fs.target</filename>, but | |
399 | for remote mount points.</para> | |
400 | ||
401 | <para>systemd automatically adds dependencies of type | |
402 | <varname>After=</varname> for this target unit to all SysV | |
403 | init script service units with an LSB header referring to | |
404 | the <literal>$remote_fs</literal> facility.</para> | |
405 | </listitem> | |
406 | </varlistentry> | |
407 | <varlistentry> | |
408 | <term><filename>rescue.target</filename></term> | |
409 | <listitem> | |
410 | <para>A special target unit for setting up the base system | |
411 | and a rescue shell.</para> | |
412 | ||
413 | <para><filename>runlevel1.target</filename> is an alias for | |
414 | this target unit, for compatibility with SysV.</para> | |
415 | </listitem> | |
416 | </varlistentry> | |
417 | <varlistentry> | |
418 | <term><filename>initrd-root-fs.target</filename></term> | |
419 | <listitem> | |
420 | <para><citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
421 | automatically adds dependencies of type | |
422 | <varname>Before=</varname> to the | |
423 | <filename>sysroot.mount</filename> unit, which is generated | |
424 | from the kernel command line. | |
425 | </para> | |
426 | </listitem> | |
427 | </varlistentry> | |
428 | <varlistentry> | |
429 | <term><filename>runlevel2.target</filename></term> | |
430 | <term><filename>runlevel3.target</filename></term> | |
431 | <term><filename>runlevel4.target</filename></term> | |
432 | <term><filename>runlevel5.target</filename></term> | |
433 | <listitem> | |
434 | <para>These are targets that are called whenever the SysV | |
435 | compatibility code asks for runlevel 2, 3, 4, 5, | |
436 | respectively. It is a good idea to make this an alias for | |
437 | (i.e. symlink to) <filename>multi-user.target</filename> | |
438 | (for runlevel 2) or <filename>graphical.target</filename> | |
439 | (the others).</para> | |
440 | </listitem> | |
441 | </varlistentry> | |
442 | <varlistentry> | |
443 | <term><filename>shutdown.target</filename></term> | |
444 | <listitem> | |
445 | <para>A special target unit that terminates the services on | |
446 | system shutdown.</para> | |
447 | ||
448 | <para>Services that shall be terminated on system shutdown | |
449 | shall add <varname>Conflicts=</varname> dependencies to this | |
450 | unit for their service unit, which is implicitly done when | |
451 | <varname>DefaultDependencies=yes</varname> is set (the | |
452 | default).</para> | |
453 | </listitem> | |
454 | </varlistentry> | |
455 | <varlistentry> | |
456 | <term><filename>sigpwr.target</filename></term> | |
457 | <listitem> | |
458 | <para>A special target that is started when systemd receives | |
459 | the SIGPWR process signal, which is normally sent by the | |
460 | kernel or UPS daemons when power fails.</para> | |
461 | </listitem> | |
462 | </varlistentry> | |
463 | <varlistentry> | |
464 | <term><filename>sleep.target</filename></term> | |
465 | <listitem> | |
466 | <para>A special target unit that is pulled in by | |
467 | <filename>suspend.target</filename>, | |
468 | <filename>hibernate.target</filename> and | |
469 | <filename>hybrid-sleep.target</filename> and may be used to | |
470 | hook units into the sleep state logic.</para> | |
471 | </listitem> | |
472 | </varlistentry> | |
473 | <varlistentry> | |
474 | <term><filename>sockets.target</filename></term> | |
475 | <listitem> | |
476 | <para>A special target unit that sets up all socket | |
477 | units.(see | |
478 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
479 | for details) that shall be active after boot.</para> | |
480 | ||
481 | <para>Services that can be socket-activated shall add | |
482 | <varname>Wants=</varname> dependencies to this unit for | |
483 | their socket unit during installation. This is best | |
484 | configured via a <varname>WantedBy=sockets.target</varname> | |
485 | in the socket unit's <literal>[Install]</literal> | |
486 | section.</para> | |
487 | </listitem> | |
488 | </varlistentry> | |
489 | <varlistentry> | |
490 | <term><filename>suspend.target</filename></term> | |
491 | <listitem> | |
492 | <para>A special target unit for suspending the system. This | |
493 | pulls in <filename>sleep.target</filename>.</para> | |
494 | </listitem> | |
495 | </varlistentry> | |
496 | <varlistentry> | |
497 | <term><filename>swap.target</filename></term> | |
498 | <listitem> | |
499 | <para>Similar to <filename>local-fs.target</filename>, but | |
500 | for swap partitions and swap files.</para> | |
501 | </listitem> | |
502 | </varlistentry> | |
503 | <varlistentry> | |
504 | <term><filename>sysinit.target</filename></term> | |
505 | <listitem> | |
506 | <para>A special target unit covering early boot-up | |
507 | scripts.</para> | |
508 | </listitem> | |
509 | </varlistentry> | |
510 | <varlistentry> | |
511 | <term><filename>syslog.socket</filename></term> | |
512 | <listitem> | |
513 | <para>The socket unit syslog implementations should listen | |
514 | on. All userspace log messages will be made available on | |
515 | this socket. For more information about syslog integration, | |
516 | please consult the <ulink | |
517 | url="http://www.freedesktop.org/wiki/Software/systemd/syslog">Syslog | |
518 | Interface</ulink> document.</para> | |
519 | </listitem> | |
520 | </varlistentry> | |
521 | <varlistentry> | |
522 | <term><filename>system-update.target</filename></term> | |
523 | <listitem> | |
524 | <para>A special target unit that is used for off-line system | |
525 | updates. | |
526 | <citerefentry><refentrytitle>systemd-system-update-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
527 | will redirect the boot process to this target if | |
528 | <filename>/system-update</filename> exists. For more | |
529 | information see the <ulink | |
530 | url="http://freedesktop.org/wiki/Software/systemd/SystemUpdates">System | |
531 | Updates Specification</ulink>.</para> | |
532 | </listitem> | |
533 | </varlistentry> | |
534 | <varlistentry> | |
535 | <term><filename>timers.target</filename></term> | |
536 | <listitem> | |
537 | <para>A special target unit that sets up all timer units | |
538 | (see | |
539 | <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
540 | for details) that shall be active after boot.</para> | |
541 | ||
542 | <para>It is recommended that timer units installed by | |
543 | applications get pulled in via <varname>Wants=</varname> | |
544 | dependencies from this unit. This is best configured via | |
545 | <varname>WantedBy=timers.target</varname> in the timer | |
546 | unit's <literal>[Install]</literal> section.</para> | |
547 | </listitem> | |
548 | </varlistentry> | |
549 | <varlistentry> | |
550 | <term><filename>umount.target</filename></term> | |
551 | <listitem> | |
552 | <para>A special target unit that umounts all mount and | |
553 | automount points on system shutdown.</para> | |
554 | ||
555 | <para>Mounts that shall be unmounted on system shutdown | |
556 | shall add Conflicts dependencies to this unit for their | |
557 | mount unit, which is implicitly done when | |
558 | <varname>DefaultDependencies=yes</varname> is set (the | |
559 | default).</para> | |
560 | </listitem> | |
561 | </varlistentry> | |
562 | ||
563 | </variablelist> | |
564 | </refsect1> | |
565 | ||
566 | <refsect1> | |
567 | <title>Special System Units for Devices</title> | |
568 | ||
569 | <para>Some target units are automatically pulled in as devices of | |
570 | certain kinds show up in the system. These may be used to | |
571 | automatically activate various services based on the specific type | |
572 | of the available hardware.</para> | |
573 | ||
574 | <variablelist> | |
575 | <varlistentry> | |
576 | <term><filename>bluetooth.target</filename></term> | |
577 | <listitem> | |
578 | <para>This target is started automatically as soon as a | |
579 | Bluetooth controller is plugged in or becomes available at | |
580 | boot.</para> | |
581 | ||
582 | <para>This may be used to pull in Bluetooth management | |
583 | daemons dynamically when Bluetooth hardware is found.</para> | |
584 | </listitem> | |
585 | </varlistentry> | |
586 | <varlistentry> | |
587 | <term><filename>printer.target</filename></term> | |
588 | <listitem> | |
589 | <para>This target is started automatically as soon as a | |
590 | printer is plugged in or becomes available at boot.</para> | |
591 | ||
592 | <para>This may be used to pull in printer management daemons | |
593 | dynamically when printer hardware is found.</para> | |
594 | </listitem> | |
595 | </varlistentry> | |
596 | <varlistentry> | |
597 | <term><filename>smartcard.target</filename></term> | |
598 | <listitem> | |
599 | <para>This target is started automatically as soon as a | |
600 | smartcard controller is plugged in or becomes available at | |
601 | boot.</para> | |
602 | ||
603 | <para>This may be used to pull in smartcard management | |
604 | daemons dynamically when smartcard hardware is found.</para> | |
605 | </listitem> | |
606 | </varlistentry> | |
607 | <varlistentry> | |
608 | <term><filename>sound.target</filename></term> | |
609 | <listitem> | |
610 | <para>This target is started automatically as soon as a | |
611 | sound card is plugged in or becomes available at | |
612 | boot.</para> | |
613 | ||
614 | <para>This may be used to pull in audio management daemons | |
615 | dynamically when audio hardware is found.</para> | |
616 | </listitem> | |
617 | </varlistentry> | |
618 | </variablelist> | |
619 | </refsect1> | |
620 | ||
621 | <refsect1> | |
622 | <title>Special Passive System Units </title> | |
623 | ||
624 | <para>A number of special system targets are defined that can be | |
625 | used to properly order boot-up of optional services. These targets | |
626 | are generally not part of the initial boot transaction, unless | |
627 | they are explicitly pulled in by one of the implementing services. | |
628 | Note specifically that these <emphasis>passive</emphasis> target | |
629 | units are generally not pulled in by the consumer of a service, | |
630 | but by the provider of the service. This means: a consuming | |
631 | service should order itself after these targets (as appropriate), | |
632 | but not pull it in. A providing service should order itself before | |
633 | these targets (as appropriate) and pull it in (via a | |
634 | <varname>Wants=</varname> type dependency).</para> | |
635 | ||
636 | <para>Note that these passive units cannot be started manually, | |
637 | i.e. <literal>systemctl start time-sync.target</literal> will fail | |
638 | with an error. They can only be pulled in by dependency. This is | |
639 | enforced since they exist for ordering purposes only and thus are | |
640 | not useful as only unit within a transaction.</para> | |
641 | ||
642 | <variablelist> | |
643 | <varlistentry> | |
644 | <term><filename>cryptsetup-pre.target</filename></term> | |
645 | <listitem> | |
646 | <para>This passive target unit may be pulled in by services | |
647 | that want to run before any encrypted block device is set | |
648 | up. All encrypted block devices are set up after this target | |
649 | has been reached. Since the shutdown order is implicitly the | |
650 | reverse start-up order between units, this target is | |
651 | particularly useful to ensure that a service is shut down | |
652 | only after all encrypted block devices are fully | |
653 | stopped.</para> | |
654 | </listitem> | |
655 | </varlistentry> | |
656 | <varlistentry> | |
657 | <term><filename>local-fs-pre.target</filename></term> | |
658 | <listitem> | |
659 | <para>This target unit is | |
660 | automatically ordered before | |
661 | all local mount points marked | |
662 | with <option>auto</option> | |
663 | (see above). It can be used to | |
664 | execute certain units before | |
665 | all local mounts.</para> | |
666 | </listitem> | |
667 | </varlistentry> | |
668 | <varlistentry> | |
669 | <term><filename>network.target</filename></term> | |
670 | <listitem> | |
671 | <para>This unit is supposed to indicate when network | |
672 | functionality is available, but it is only very weakly | |
673 | defined what that is supposed to mean, with one exception: | |
674 | at shutdown, a unit that is ordered after | |
675 | <filename>network.target</filename> will be stopped before | |
676 | the network -- to whatever level it might be set up then -- | |
677 | is shut down. It is hence useful when writing service files | |
678 | that require network access on shutdown, which should order | |
679 | themselves after this target, but not pull it in. Also see | |
680 | <ulink url="http://www.freedesktop.org/wiki/Software/systemd/NetworkTarget">Running | |
681 | Services After the Network is up</ulink> for more | |
682 | information. Also see | |
683 | <filename>network-online.target</filename> described | |
684 | above.</para> | |
685 | ||
686 | <para>systemd automatically adds dependencies of type | |
687 | <varname>After=</varname> for this target unit to all SysV | |
688 | init script service units with an LSB header referring to | |
689 | the <literal>$network</literal> facility.</para> | |
690 | </listitem> | |
691 | </varlistentry> | |
692 | <varlistentry> | |
693 | <term><filename>network-pre.target</filename></term> | |
694 | <listitem> | |
695 | <para>This passive target unit may be pulled in by services | |
696 | that want to run before any network is set up, for example | |
697 | for the purpose of setting up a firewall. All network | |
698 | management software orders itself after this target, but | |
699 | does not pull it in.</para> | |
700 | </listitem> | |
701 | </varlistentry> | |
702 | <varlistentry> | |
703 | <term><filename>nss-lookup.target</filename></term> | |
704 | <listitem> | |
705 | <para>A target that should be used as synchronization point | |
706 | for all host/network name service lookups. Note that this is | |
707 | independent of user/group name lookups for which | |
708 | <filename>nss-user-lookup.target</filename> should be used. | |
709 | All services for which the availability of full host/network | |
710 | name resolution is essential should be ordered after this | |
711 | target, but not pull it in. systemd automatically adds | |
712 | dependencies of type <varname>After=</varname> for this | |
713 | target unit to all SysV init script service units with an | |
714 | LSB header referring to the <literal>$named</literal> | |
715 | facility.</para> | |
716 | </listitem> | |
717 | </varlistentry> | |
718 | <varlistentry> | |
719 | <term><filename>nss-user-lookup.target</filename></term> | |
720 | <listitem> | |
721 | <para>A target that should be used as synchronization point | |
722 | for all user/group name service lookups. Note that this is | |
723 | independent of host/network name lookups for which | |
724 | <filename>nss-lookup.target</filename> should be used. All | |
725 | services for which the availability of the full user/group | |
726 | database is essential should be ordered after this target, | |
727 | but not pull it in. Note that system users are always | |
728 | resolvable, and hence do not require any special ordering | |
729 | against this target.</para> | |
730 | </listitem> | |
731 | </varlistentry> | |
732 | <varlistentry> | |
733 | <term><filename>remote-fs-pre.target</filename></term> | |
734 | <listitem> | |
735 | <para>This target unit is automatically ordered before all | |
736 | remote mount point units (see above). It can be used to run | |
737 | certain units before the remote mounts are established. Note | |
738 | that this unit is generally not part of the initial | |
739 | transaction, unless the unit that wants to be ordered before | |
740 | all remote mounts pulls it in via a | |
741 | <varname>Wants=</varname> type dependency. If the unit wants | |
742 | to be pulled in by the first remote mount showing up, it | |
743 | should use <filename>network-online.target</filename> (see | |
744 | above).</para> | |
745 | </listitem> | |
746 | </varlistentry> | |
747 | <varlistentry> | |
748 | <term><filename>rpcbind.target</filename></term> | |
749 | <listitem> | |
750 | <para>The portmapper/rpcbind pulls in this target and orders | |
751 | itself before it, to indicate its availability. systemd | |
752 | automatically adds dependencies of type | |
753 | <varname>After=</varname> for this target unit to all SysV | |
754 | init script service units with an LSB header referring to | |
755 | the <literal>$portmap</literal> facility.</para> | |
756 | </listitem> | |
757 | </varlistentry> | |
758 | <varlistentry> | |
759 | <term><filename>time-sync.target</filename></term> | |
760 | <listitem> | |
761 | <para>Services responsible for synchronizing the system | |
762 | clock from a remote source (such as NTP client | |
763 | implementations) should pull in this target and order | |
764 | themselves before it. All services where correct time is | |
765 | essential should be ordered after this unit, but not pull it | |
766 | in. systemd automatically adds dependencies of type | |
767 | <varname>After=</varname> for this target unit to all SysV | |
768 | init script service units with an LSB header referring to | |
769 | the <literal>$time</literal> facility. </para> | |
770 | </listitem> | |
771 | </varlistentry> | |
772 | </variablelist> | |
773 | </refsect1> | |
774 | ||
775 | <refsect1> | |
776 | <title>Special User Units</title> | |
777 | ||
778 | <para>When systemd runs as a user instance, the following special | |
779 | units are available, which have similar definitions as their | |
780 | system counterparts: | |
781 | <filename>default.target</filename>, | |
782 | <filename>shutdown.target</filename>, | |
783 | <filename>sockets.target</filename>, | |
784 | <filename>timers.target</filename>, | |
785 | <filename>paths.target</filename>, | |
786 | <filename>bluetooth.target</filename>, | |
787 | <filename>printer.target</filename>, | |
788 | <filename>smartcard.target</filename>, | |
789 | <filename>sound.target</filename>.</para> | |
790 | ||
791 | <para>In addition, the following special unit is understood only | |
792 | when systemd runs as service instance:</para> | |
793 | ||
794 | <variablelist> | |
795 | <varlistentry> | |
796 | <term><filename>exit.target</filename></term> | |
797 | <listitem> | |
798 | <para>A special service unit for shutting down the user | |
799 | service manager.</para> | |
800 | ||
801 | <para>Applications wanting to terminate the user service | |
802 | manager should start this unit. If systemd receives | |
803 | <constant>SIGTERM</constant> or <constant>SIGINT</constant> | |
804 | when running as user service daemon, it will start this | |
805 | unit.</para> | |
806 | ||
807 | <para>Normally, this pulls in | |
808 | <filename>shutdown.target</filename> which in turn should be | |
809 | conflicted by all units that want to be shut down on user | |
810 | service manager exit.</para> | |
811 | </listitem> | |
812 | </varlistentry> | |
813 | </variablelist> | |
814 | </refsect1> | |
815 | ||
816 | <refsect1> | |
817 | <title>Special Slice Units</title> | |
818 | ||
819 | <para>There are four <literal>.slice</literal> units which form | |
820 | the basis of the hierarchy for assignment of resources for | |
821 | services, users, and virtual machines or containers.</para> | |
822 | ||
823 | <variablelist> | |
824 | <varlistentry> | |
825 | <term><filename>-.slice</filename></term> | |
826 | <listitem> | |
827 | <para>The root slice is the root of the hierarchy. It | |
828 | usually does not contain units directly, but may be used to | |
829 | set defaults for the whole tree.</para> | |
830 | </listitem> | |
831 | </varlistentry> | |
832 | ||
833 | <varlistentry> | |
834 | <term><filename>system.slice</filename></term> | |
835 | <listitem> | |
836 | <para>By default, all services services started by | |
837 | <command>systemd</command> are found in this slice.</para> | |
838 | </listitem> | |
839 | </varlistentry> | |
840 | ||
841 | <varlistentry> | |
842 | <term><filename>user.slice</filename></term> | |
843 | <listitem> | |
844 | <para>By default, all user processes and services started on | |
845 | behalf of the user, including the per-user systemd instance | |
846 | are found in this slice.</para> | |
847 | </listitem> | |
848 | </varlistentry> | |
849 | ||
850 | <varlistentry> | |
851 | <term><filename>machine.slice</filename></term> | |
852 | <listitem> | |
853 | <para>By default, all virtual machines and containers | |
854 | registered with <command>systemd-machined</command> are | |
855 | found in this slice. | |
856 | </para> | |
857 | </listitem> | |
858 | </varlistentry> | |
859 | </variablelist> | |
860 | </refsect1> | |
861 | ||
862 | <refsect1> | |
863 | <title>See Also</title> | |
864 | <para> | |
865 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
866 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
867 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
868 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
869 | <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
870 | <citerefentry><refentrytitle>systemd.slice</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
871 | <citerefentry project='man-pages'><refentrytitle>bootup</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
872 | <citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
873 | </para> | |
874 | </refsect1> | |
9f235308 LP |
875 | |
876 | </refentry> |