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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 | ||
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 | |
11 | under the terms of the GNU General Public License as published by | |
12 | the Free Software Foundation; either version 2 of the License, or | |
13 | (at your option) any later version. | |
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 | |
18 | General Public License for more details. | |
19 | ||
20 | You should have received a copy of the GNU General Public License | |
21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
22 | --> | |
23 | ||
24 | <refentry id="systemd"> | |
25 | ||
26 | <refentryinfo> | |
27 | <title>systemd</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</refentrytitle> | |
160cd5c9 | 42 | <manvolnum>1</manvolnum> |
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43 | </refmeta> |
44 | ||
45 | <refnamediv> | |
46 | <refname>systemd</refname> | |
6f6083dc | 47 | <refname>init</refname> |
9e632bf7 LP |
48 | <refpurpose>systemd System and Session Manager</refpurpose> |
49 | </refnamediv> | |
50 | ||
2218198b LP |
51 | <refsynopsisdiv> |
52 | <cmdsynopsis> | |
160cd5c9 | 53 | <command>systemd <arg choice="opt" rep="repeat">OPTIONS</arg></command> |
2218198b LP |
54 | </cmdsynopsis> |
55 | <cmdsynopsis> | |
160cd5c9 | 56 | <command>init <arg choice="opt" rep="repeat">OPTIONS</arg> <arg choice="req">COMMAND</arg></command> |
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57 | </cmdsynopsis> |
58 | </refsynopsisdiv> | |
59 | ||
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60 | <refsect1> |
61 | <title>Description</title> | |
62 | ||
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63 | <para>systemd is a system and session manager for |
64 | Linux operating systems. When run as first process on | |
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65 | boot (as PID 1), it acts as init system that brings |
66 | up and maintains userspace services.</para> | |
2218198b | 67 | |
af62c704 | 68 | <para>For compatibility with SysV, if systemd is called |
2218198b | 69 | as <command>init</command> and a PID that is not |
af62c704 | 70 | 1, it will execute <command>telinit</command> and pass |
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71 | all command line arguments unmodified. That means |
72 | <command>init</command> and <command>telinit</command> | |
73 | are mostly equivalent when invoked from normal login sessions. See | |
74 | <citerefentry><refentrytitle>telinit</refentrytitle><manvolnum>8</manvolnum></citerefentry> | |
75 | for more information.</para> | |
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76 | |
77 | <para>When run as system instance, systemd interprets | |
78 | the configuration file | |
79 | <filename>system.conf</filename>, otherwise | |
80 | <filename>session.conf</filename>. See | |
81 | <citerefentry><refentrytitle>systemd.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
82 | for more information.</para> | |
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83 | </refsect1> |
84 | ||
85 | <refsect1> | |
86 | <title>Options</title> | |
87 | ||
88 | <para>The following options are understood:</para> | |
89 | ||
90 | <variablelist> | |
91 | <varlistentry> | |
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92 | <term><option>-h</option></term> |
93 | <term><option>--help</option></term> | |
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94 | |
95 | <listitem><para>Prints a short help | |
96 | text and exits.</para></listitem> | |
97 | </varlistentry> | |
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98 | <varlistentry> |
99 | <term><option>--test</option></term> | |
100 | ||
101 | <listitem><para>Determine startup | |
102 | sequence, dump it and exit. This is an | |
103 | option useful for debugging | |
104 | only.</para></listitem> | |
105 | </varlistentry> | |
106 | <varlistentry> | |
107 | <term><option>--dump-configuration-items</option></term> | |
108 | ||
109 | <listitem><para>Dump understood unit | |
110 | configuration items. This outputs a | |
111 | terse but complete list of | |
112 | configuration items understood in unit | |
113 | definition files.</para></listitem> | |
114 | </varlistentry> | |
115 | <varlistentry> | |
116 | <term><option>--introspect=</option></term> | |
117 | ||
118 | <listitem><para>Extract D-Bus | |
119 | interface introspection data. This is | |
ad678a06 | 120 | mostly useful at install time |
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121 | to generate data suitable for the |
122 | D-Bus interfaces | |
123 | repository. Optionally the interface | |
124 | name for the introspection data may be | |
125 | specified. If omitted, the | |
126 | introspection data for all interfaces | |
127 | is dumped.</para></listitem> | |
128 | </varlistentry> | |
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129 | <varlistentry> |
130 | <term><option>--unit=</option></term> | |
131 | ||
132 | <listitem><para>Set default unit to | |
133 | activate on startup. If not specified | |
134 | defaults to | |
135 | <filename>default.target</filename>.</para></listitem> | |
136 | </varlistentry> | |
137 | <varlistentry> | |
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138 | <term><option>--system</option></term> |
139 | <term><option>--session</option></term> | |
140 | ||
141 | <listitem><para>Tell systemd to run a | |
142 | system instance (resp. session | |
143 | instance), even if the process ID is | |
b9975629 | 144 | not 1 (resp. is 1), i.e. systemd is not |
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145 | (resp. is) run as init process. |
146 | Normally it should not be necessary to | |
147 | pass these options, as systemd | |
148 | automatically detects the mode it is | |
149 | started in. These options are hence of | |
150 | little use except for | |
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151 | debugging.</para></listitem> |
152 | </varlistentry> | |
153 | <varlistentry> | |
f3e219a2 | 154 | <term><option>--dump-core</option></term> |
2218198b | 155 | |
f3e219a2 | 156 | <listitem><para>Dump core on crash. This switch has no effect when run as session instance.</para></listitem> |
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157 | </varlistentry> |
158 | <varlistentry> | |
f3e219a2 | 159 | <term><option>--crash-shell</option></term> |
2218198b | 160 | |
f3e219a2 | 161 | <listitem><para>Run shell on crash. This switch has no effect when run as session instance.</para></listitem> |
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162 | </varlistentry> |
163 | <varlistentry> | |
164 | <term><option>--confirm-spawn</option></term> | |
165 | ||
f3e219a2 | 166 | <listitem><para>Ask for confirmation when spawning processes. This switch has no effect when run as session instance.</para></listitem> |
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167 | </varlistentry> |
168 | <varlistentry> | |
69dd2852 LP |
169 | <term><option>--show-status=</option></term> |
170 | ||
171 | <listitem><para>Show terse service | |
172 | status information while booting. This | |
173 | switch has no effect when run as | |
174 | session instance. Takes a boolean | |
175 | argument which may be omitted | |
176 | which is interpreted as | |
177 | <option>true</option>.</para></listitem> | |
178 | </varlistentry> | |
179 | <varlistentry> | |
180 | <term><option>--sysv-console=</option></term> | |
2218198b | 181 | |
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182 | <listitem><para>Controls whether |
183 | output of SysV init scripts will be | |
184 | directed to the console. This switch | |
185 | has no effect when run as session | |
186 | instance. Takes a boolean argument | |
187 | which may be omitted which is | |
188 | interpreted as | |
189 | <option>true</option>.</para></listitem> | |
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190 | </varlistentry> |
191 | <varlistentry> | |
192 | <term><option>--log-target=</option></term> | |
193 | ||
194 | <listitem><para>Set log | |
195 | target. Argument must be one of | |
196 | <option>console</option>, | |
197 | <option>syslog</option>, | |
198 | <option>kmsg</option>, | |
199 | <option>syslog-or-kmsg</option>, | |
200 | <option>null</option>.</para></listitem> | |
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201 | </varlistentry> |
202 | <varlistentry> | |
203 | <term><option>--log-level=</option></term> | |
204 | ||
205 | <listitem><para>Set log level. As | |
206 | argument this accepts a numerical log | |
207 | level or the well-known <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
208 | symbolic names (lowercase): | |
209 | <option>emerg</option>, | |
210 | <option>alert</option>, | |
211 | <option>crit</option>, | |
212 | <option>err</option>, | |
213 | <option>warning</option>, | |
214 | <option>notice</option>, | |
215 | <option>info</option>, | |
216 | <option>debug</option>.</para></listitem> | |
217 | </varlistentry> | |
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218 | <varlistentry> |
219 | <term><option>--log-color=</option></term> | |
220 | ||
221 | <listitem><para>Highlight important | |
222 | log messages. Argument is a boolean | |
223 | value. If the argument is omitted it | |
224 | defaults to | |
225 | <option>true</option>.</para></listitem> | |
226 | </varlistentry> | |
227 | <varlistentry> | |
228 | <term><option>--log-location=</option></term> | |
229 | ||
230 | <listitem><para>Include code location | |
231 | in log messages. This is mostly | |
232 | relevant for debugging | |
233 | purposes. Argument is a boolean | |
234 | value. If the argument is omitted | |
235 | it defaults to | |
236 | <option>true</option>.</para></listitem> | |
237 | </varlistentry> | |
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238 | </variablelist> |
239 | </refsect1> | |
240 | ||
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241 | <refsect1> |
242 | <title>Concepts</title> | |
243 | ||
244 | <para>systemd provides a dependency system between | |
245 | various entities called "units". Units encapsulate | |
246 | various objects that are relevant for system boot-up | |
5632e374 | 247 | and maintenance. The majority of units are configured |
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248 | in unit configuration files, whose syntax and basic |
249 | set of options is described in | |
250 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
251 | however some are created automatically from other | |
252 | configuration or dynamically from system state. Units | |
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253 | may be 'active' (meaning started, bound, plugged in, |
254 | ... depending on the unit type, see below), or | |
255 | 'inactive' (meaning stopped, unbound, unplugged, ...), | |
256 | as well as in the process of being activated or | |
257 | deactivated, i.e. between the two states (these states | |
258 | are called 'activating', 'deactivating'). A special | |
259 | 'maintenance' state is available as well which is very | |
260 | similar to 'inactive' and is entered when the service | |
261 | failed in some way (process returned error code on | |
262 | exit, or crashed, or an operation timed out). If this | |
263 | state is entered the cause will be logged, for later | |
264 | reference. Note that the various unit types may have a | |
265 | number of additional substates, which are mapped to | |
266 | the five generalized unit states described | |
267 | here.</para> | |
268 | ||
269 | <para>The following unit types are available:</para> | |
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270 | |
271 | <orderedlist> | |
272 | <listitem><para>Service units, which control | |
273 | daemons and the processes they consist of. For | |
274 | details see | |
275 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
276 | ||
277 | <listitem><para>Socket units, which | |
278 | encapsulate local IPC or network sockets in | |
279 | the system, useful for socket-based | |
280 | activation. For details about socket units see | |
281 | <citerefentry><refentrytitle>systemd.socket</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
282 | for details on socket-based activation and | |
283 | other forms of activation, see | |
284 | <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para></listitem> | |
285 | ||
286 | <listitem><para>Target units are useful to | |
287 | group units, or provide well-known | |
288 | synchronization points during boot-up, see | |
289 | <citerefentry><refentrytitle>systemd.target</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
290 | ||
291 | <listitem><para>Device units expose kernel | |
292 | devices in systemd and may be used to | |
293 | implement device-based activation. For details | |
294 | see | |
295 | <citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
296 | ||
297 | <listitem><para>Mount units control mount | |
298 | points in the file system, for details see | |
299 | <citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
300 | ||
301 | <listitem><para>Automount units provide | |
302 | automount capabilities, for on-demand mounting | |
303 | of file systems as well as parallelized | |
304 | boot-up. See | |
305 | <citerefentry><refentrytitle>systemd.automount</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
306 | ||
307 | <listitem><para>Snapshot units can be used to | |
308 | temporarily save the state of the set of | |
309 | systemd units, which later may be restored by | |
310 | activating the saved snapshot unit. For more | |
311 | information see | |
7461d1b7 | 312 | <citerefentry><refentrytitle>systemd.snapshot</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> |
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313 | |
314 | <listitem><para>Timer units are useful for | |
315 | triggering activation of other units based on | |
316 | timers. You may find details in | |
317 | <citerefentry><refentrytitle>systemd.timer</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
318 | ||
319 | <listitem><para>Swap units are very similar to | |
320 | mount units and encapsulated memory swap | |
321 | partitions or files of the operating | |
322 | systemd. They are described in <citerefentry><refentrytitle>systemd.swap</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
323 | ||
324 | <listitem><para>Path units may be used | |
dccb2600 | 325 | to activate other services when file system |
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326 | objects change or are modified. See |
327 | <citerefentry><refentrytitle>systemd.path</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para></listitem> | |
328 | ||
329 | </orderedlist> | |
330 | ||
331 | <para>Units are named as their configuration | |
332 | files. Some units have special semantics. A detailed | |
333 | list you may find in | |
334 | <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para> | |
335 | ||
b9975629 LP |
336 | <para>systemd knows various kinds of dependencies, |
337 | including positive and negative requirement | |
338 | dependencies (i.e. <varname>Requires=</varname> and | |
339 | <varname>Conflicts=</varname>) as well as ordering | |
340 | dependencies (<varname>After=</varname> and | |
341 | <varname>Before=</varname>). NB: ordering and | |
342 | requirement dependencies are orthogonal. If only a | |
343 | requirement dependency exists between two units | |
344 | (e.g. <filename>foo.service</filename> requires | |
345 | <filename>bar.service</filename>), but no ordering | |
346 | dependency (e.g. <filename>foo.service</filename> | |
347 | after <filename>bar.service</filename>) and both are | |
348 | requested to start, they will be started in | |
349 | parallel. It is a common pattern that both requirement | |
350 | and ordering dependencies are placed between two | |
351 | units. Also note that the majority of dependencies are | |
352 | implicitly created and maintained by systemd. In most | |
353 | cases it should be unnecessary to declare additional | |
354 | dependencies manually, however it is possible to do | |
355 | this.</para> | |
356 | ||
357 | <para>Application programs and units (via | |
358 | dependencies) may requests state changes of units. In | |
359 | systemd, these requests are encapsulated as 'jobs' and | |
360 | maintained in a job queue. Jobs may succeed or can | |
361 | fail, their execution is ordered based on the ordering | |
362 | dependencies of the units they have been scheduled | |
363 | for.</para> | |
364 | ||
99ffae46 | 365 | <para>On boot systemd activates the target unit |
dccb2600 | 366 | <filename>default.target</filename> whose job is to |
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367 | activate on-boot services and other on-boot units by |
368 | pulling them in via dependencies. Usually the unit | |
369 | name is just an alias (symlink) for either | |
370 | <filename>graphical.target</filename> (for | |
371 | fully-featured boots into the UI) or | |
372 | <filename>multi-user.target</filename> (for limited | |
373 | console-only boots for use in embedded or server | |
374 | environments, or similar; a subset of | |
375 | graphical.target). However it is at the discretion of | |
376 | the administrator to configure it as an alias to any | |
377 | other target unit. See | |
378 | <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
379 | for details about these target units.</para> | |
380 | ||
dccb2600 | 381 | <para>Processes systemd spawns are placed in |
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382 | individual Linux control groups named after the unit |
383 | which they belong to in the private systemd | |
384 | hierarchy. (see <ulink | |
385 | url="http://www.kernel.org/doc/Documentation/cgroups/cgroups.txt">cgroups.txt</ulink> | |
386 | for more information about control groups, or short | |
387 | "cgroups"). systemd uses this to effectively keep | |
388 | track of processes. Control group information is | |
389 | maintained in the kernel, and is accessible via the | |
390 | file system hierarchy (beneath | |
391 | <filename>/cgroup/systemd/</filename>), or in tools | |
392 | such as | |
393 | <citerefentry><refentrytitle>ps</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
394 | (<command>ps xawf -eo pid,user,cgroup,args</command> | |
395 | is particularly useful to list all processes and the | |
396 | systemd units they belong to.).</para> | |
397 | ||
398 | <para>systemd is compatible with the SysV init system | |
399 | to a large degree: SysV init scripts are supported and | |
400 | simply read as an alternative (though limited) | |
401 | configuration file format. The SysV | |
402 | <filename>/dev/initctl</filename> interface is | |
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403 | provided, and compatibility implementations of the |
404 | various SysV client tools are available. In addition to | |
405 | that, various established Unix functionality such as | |
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406 | <filename>/etc/fstab</filename> or the |
407 | <filename>utmp</filename> database are | |
408 | supported.</para> | |
409 | ||
410 | <para>systemd has a minimal transaction system: if a | |
411 | unit is requested to start up or shut down it will add | |
412 | it and all its dependencies to a temporary | |
413 | transaction. Then, it will verify if the transaction | |
414 | is consistent (i.e. whether the ordering of all units | |
415 | is cycle-free). If it is not, systemd will try to fix | |
416 | it up, and removes non-essential jobs from the | |
417 | transaction that might remove the loop. Also, systemd | |
418 | tries to suppress non-essential jobs in the | |
419 | transaction that would stop a running service. Finally | |
420 | it is checked whether the jobs of the transaction | |
421 | contradict jobs that have already been queued, and | |
422 | optionally the transaction is aborted then. If all | |
423 | worked out and the transaction is consistent and | |
424 | minimized in its impact it is merged with all already | |
425 | outstanding jobs and added to the run | |
426 | queue. Effectively this means that before executing a | |
427 | requested operation, systemd will verify that it makes | |
428 | sense, fixing it if possible, and only failing if it | |
429 | really cannot work.</para> | |
430 | ||
431 | <para>Systemd contains native implementations of | |
432 | various tasks that need to be executed as part of the | |
433 | boot process. For example, it sets the host name or | |
434 | configures the loopback network device. It also sets | |
435 | up and mounts various API file systems, such as | |
436 | <filename>/sys</filename> or | |
437 | <filename>/proc</filename>.</para> | |
438 | ||
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439 | <para>For more information about the concepts and |
440 | ideas behind systemd please refer to the <ulink | |
441 | url="http://0pointer.de/blog/projects/systemd.html">Original | |
59a3e1bc | 442 | Design Document</ulink>.</para> |
99ffae46 LP |
443 | </refsect1> |
444 | ||
160cd5c9 LP |
445 | <refsect1> |
446 | <title>Directories</title> | |
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447 | |
448 | <variablelist> | |
449 | <varlistentry> | |
450 | <term>System unit directories</term> | |
451 | ||
452 | <listitem><para>The systemd system | |
453 | manager reads unit configuration from | |
454 | various directories. Packages that | |
455 | want to install unit files shall place | |
456 | them in the directory returned by | |
457 | <command>pkg-config systemd | |
458 | --variable=systemdsystemunitdir</command>. Other | |
459 | directories checked are | |
460 | <filename>/usr/local/share/systemd/system</filename> | |
461 | and | |
462 | <filename>/usr/share/systemd/system</filename>. User | |
463 | configuration always takes | |
464 | precedence. <command>pkg-config | |
465 | systemd | |
466 | --variable=systemdsystemconfdir</command> | |
467 | returns the path of the system | |
468 | configuration directory. Packages | |
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469 | should alter the content of these |
470 | directories only with the | |
471 | <command>enable</command> and | |
472 | <command>disable</command> commands of | |
473 | the | |
474 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
7874bcd6 LP |
475 | tool.</para></listitem> |
476 | </varlistentry> | |
477 | </variablelist> | |
478 | ||
479 | <variablelist> | |
480 | <varlistentry> | |
481 | <term>Session unit directories</term> | |
482 | ||
483 | <listitem><para>Similar rules apply | |
484 | for the session unit | |
485 | directories. However, here the <ulink | |
486 | url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG | |
487 | Base Directory specification</ulink> | |
488 | is followed to find | |
489 | units. Applications should place their | |
490 | unit files in the directory returned | |
491 | by <command>pkg-config systemd | |
492 | --variable=systemdsessionunitdir</command>. Global | |
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493 | configuration is done in the directory |
494 | reported by <command>pkg-config | |
495 | systemd | |
7874bcd6 | 496 | --variable=systemdsessionconfdir</command>. The |
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497 | <command>enable</command> and |
498 | <command>disable</command> commands of | |
499 | the | |
500 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
7874bcd6 LP |
501 | tool can handle both global (i.e. for |
502 | all users) and private (for one user) | |
503 | enabling/disabling of | |
504 | units.</para></listitem> | |
505 | </varlistentry> | |
506 | </variablelist> | |
507 | ||
508 | <variablelist> | |
509 | <varlistentry> | |
510 | <term>SysV init scripts directory</term> | |
511 | ||
512 | <listitem><para>The location of the | |
513 | SysV init script directory varies | |
514 | between distributions. If systemd | |
515 | cannot find a native unit file for a | |
af62c704 | 516 | requested service, it will look for a |
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517 | SysV init script of the same name |
518 | (with the | |
519 | <filename>.service</filename> suffix | |
520 | removed).</para></listitem> | |
521 | </varlistentry> | |
522 | </variablelist> | |
523 | ||
524 | <variablelist> | |
525 | <varlistentry> | |
526 | <term>SysV runlevel link farm directory</term> | |
527 | ||
528 | <listitem><para>The location of the | |
529 | SysV runlevel link farm directory | |
530 | varies between distributions. systemd | |
531 | will take the link farm into account | |
532 | when figuring out whether a service | |
533 | shall be enabled. Note that a service | |
534 | unit with a native unit configuration | |
edb9aaa8 | 535 | file cannot be started by activating it |
7874bcd6 LP |
536 | in the SysV runlevel link |
537 | farm.</para></listitem> | |
538 | </varlistentry> | |
539 | </variablelist> | |
160cd5c9 LP |
540 | </refsect1> |
541 | ||
542 | <refsect1> | |
7874bcd6 | 543 | <title>Signals</title> |
160cd5c9 LP |
544 | |
545 | <variablelist> | |
546 | <varlistentry> | |
7874bcd6 LP |
547 | <term>SIGTERM</term> |
548 | ||
549 | <listitem><para>Upon receiving this | |
550 | signal the systemd system manager | |
551 | serializes its state, reexecutes | |
552 | itself and deserializes the saved | |
553 | state again. This is mostly equivalent | |
554 | to <command>systemctl | |
555 | daemon-reexec</command>.</para> | |
556 | ||
557 | <para>systemd session managers will | |
558 | start the | |
559 | <filename>exit.target</filename> unit | |
560 | when this signal is received. This is | |
561 | mostly equivalent to | |
562 | <command>systemctl --session start | |
563 | exit.target</command>.</para></listitem> | |
564 | </varlistentry> | |
565 | ||
566 | <varlistentry> | |
567 | <term>SIGINT</term> | |
568 | ||
569 | <listitem><para>Upon receiving this | |
570 | signal the systemd system manager will | |
571 | start the | |
572 | <filename>ctrl-alt-del.target</filename> unit. This | |
573 | is mostly equivalent to | |
574 | <command>systemctl start | |
575 | ctl-alt-del.target</command>.</para> | |
576 | ||
577 | <para>systemd session managers | |
578 | treat this signal the same way as | |
579 | SIGTERM.</para></listitem> | |
580 | </varlistentry> | |
581 | ||
582 | <varlistentry> | |
583 | <term>SIGWINCH</term> | |
584 | ||
585 | <listitem><para>When this signal is | |
586 | received the systemd system manager | |
587 | will start the | |
588 | <filename>kbrequest.target</filename> | |
589 | unit. This is mostly equivalent to | |
590 | <command>systemctl start | |
591 | kbrequest.target</command>.</para> | |
592 | ||
593 | <para>This signal is ignored by | |
594 | systemd session | |
595 | managers.</para></listitem> | |
596 | </varlistentry> | |
597 | ||
598 | <varlistentry> | |
599 | <term>SIGPWR</term> | |
600 | ||
601 | <listitem><para>When this signal is | |
602 | received the systemd manager | |
603 | will start the | |
604 | <filename>sigpwr.target</filename> | |
605 | unit. This is mostly equivalent to | |
606 | <command>systemctl start | |
607 | sigpwr.target</command>.</para></listitem> | |
608 | </varlistentry> | |
609 | ||
610 | <varlistentry> | |
611 | <term>SIGUSR1</term> | |
612 | ||
613 | <listitem><para>When this signal is | |
614 | received the systemd manager will try | |
615 | to reconnect to the D-Bus | |
616 | bus.</para></listitem> | |
617 | </varlistentry> | |
618 | ||
619 | <varlistentry> | |
620 | <term>SIGUSR2</term> | |
621 | ||
622 | <listitem><para>When this signal is | |
623 | received the systemd manager will log | |
624 | its complete state in human readable | |
625 | form. The data logged is the same as | |
626 | printed by <command>systemctl | |
627 | dump</command>.</para></listitem> | |
628 | </varlistentry> | |
629 | ||
630 | <varlistentry> | |
631 | <term>SIGHUP</term> | |
632 | ||
633 | <listitem><para>Reloads the complete | |
634 | daemon configuration. This is mostly | |
635 | equivalent to <command>systemctl | |
636 | daemon-reload</command>.</para></listitem> | |
637 | </varlistentry> | |
638 | ||
639 | <varlistentry> | |
640 | <term>SIGRTMIN+0</term> | |
641 | ||
642 | <listitem><para>Enters default mode, starts the | |
643 | <filename>default.target</filename> | |
644 | unit. This is mostly equivalent to | |
645 | <command>systemctl start | |
646 | default.target</command>.</para></listitem> | |
647 | </varlistentry> | |
648 | ||
649 | <varlistentry> | |
650 | <term>SIGRTMIN+1</term> | |
651 | ||
652 | <listitem><para>Enters rescue mode, | |
653 | starts the | |
654 | <filename>rescue.target</filename> | |
655 | unit. This is mostly equivalent to | |
656 | <command>systemctl isolate | |
657 | rescue.target</command>.</para></listitem> | |
658 | </varlistentry> | |
160cd5c9 | 659 | |
7874bcd6 LP |
660 | <varlistentry> |
661 | <term>SIGRTMIN+2</term> | |
662 | ||
663 | <listitem><para>Enters emergency mode, | |
664 | starts the | |
665 | <filename>emergency.service</filename> | |
666 | unit. This is mostly equivalent to | |
667 | <command>systemctl isolate | |
668 | emergency.service</command>.</para></listitem> | |
669 | </varlistentry> | |
670 | ||
671 | <varlistentry> | |
672 | <term>SIGRTMIN+3</term> | |
673 | ||
674 | <listitem><para>Halts the machine, | |
675 | starts the | |
676 | <filename>halt.target</filename> | |
677 | unit. This is mostly equivalent to | |
678 | <command>systemctl start | |
679 | halt.target</command>.</para></listitem> | |
680 | </varlistentry> | |
681 | ||
682 | <varlistentry> | |
683 | <term>SIGRTMIN+4</term> | |
684 | ||
685 | <listitem><para>Powers off the machine, | |
686 | starts the | |
687 | <filename>poweroff.target</filename> | |
688 | unit. This is mostly equivalent to | |
689 | <command>systemctl start | |
690 | poweroff.target</command>.</para></listitem> | |
691 | </varlistentry> | |
692 | ||
693 | <varlistentry> | |
694 | <term>SIGRTMIN+5</term> | |
695 | ||
696 | <listitem><para>Reboots the machine, | |
697 | starts the | |
698 | <filename>reboot.target</filename> | |
699 | unit. This is mostly equivalent to | |
700 | <command>systemctl start | |
701 | reboot.target</command>.</para></listitem> | |
160cd5c9 LP |
702 | </varlistentry> |
703 | </variablelist> | |
704 | </refsect1> | |
705 | ||
7874bcd6 LP |
706 | <refsect1> |
707 | <title>Environment</title> | |
708 | ||
709 | <variablelist> | |
710 | <varlistentry> | |
711 | <term><varname>$SYSTEMD_LOG_LEVEL</varname></term> | |
712 | <listitem><para>systemd reads the | |
713 | log level from this environment | |
436c44a5 | 714 | variable. This can be overridden with |
7874bcd6 LP |
715 | <option>--log-level=</option>.</para></listitem> |
716 | </varlistentry> | |
717 | ||
718 | <varlistentry> | |
719 | <term><varname>$SYSTEMD_LOG_TARGET</varname></term> | |
720 | <listitem><para>systemd reads the | |
721 | log target from this environment | |
436c44a5 | 722 | variable. This can be overridden with |
7874bcd6 LP |
723 | <option>--log-target=</option>.</para></listitem> |
724 | </varlistentry> | |
725 | ||
726 | <varlistentry> | |
727 | <term><varname>$SYSTEMD_LOG_COLOR</varname></term> | |
728 | <listitem><para>Controls whether | |
729 | systemd highlights important log | |
436c44a5 | 730 | messages. This can be overridden with |
7874bcd6 LP |
731 | <option>--log-color=</option>.</para></listitem> |
732 | </varlistentry> | |
733 | ||
734 | <varlistentry> | |
735 | <term><varname>$SYSTEMD_LOG_LOCATION</varname></term> | |
736 | <listitem><para>Controls whether | |
737 | systemd prints the code location along | |
738 | with log messages. This can be | |
436c44a5 | 739 | overridden with |
7874bcd6 LP |
740 | <option>--log-location=</option>.</para></listitem> |
741 | </varlistentry> | |
742 | ||
743 | <varlistentry> | |
744 | <term><varname>$XDG_CONFIG_HOME</varname></term> | |
745 | <term><varname>$XDG_CONFIG_DIRS</varname></term> | |
746 | <term><varname>$XDG_DATA_HOME</varname></term> | |
747 | <term><varname>$XDG_DATA_DIRS</varname></term> | |
748 | ||
749 | <listitem><para>The systemd session | |
750 | manager uses these variables in | |
751 | accordance to the <ulink | |
752 | url="http://standards.freedesktop.org/basedir-spec/basedir-spec-latest.html">XDG | |
753 | Base Directory specification</ulink> | |
754 | to find its configuration.</para></listitem> | |
755 | </varlistentry> | |
756 | ||
757 | <varlistentry> | |
758 | <term><varname>$SYSTEMD_UNIT_PATH</varname></term> | |
759 | ||
760 | <listitem><para>Controls where systemd | |
761 | looks for unit | |
762 | files.</para></listitem> | |
763 | </varlistentry> | |
764 | ||
765 | <varlistentry> | |
766 | <term><varname>$SYSTEMD_SYSVINIT_PATH</varname></term> | |
767 | ||
768 | <listitem><para>Controls where systemd | |
769 | looks for SysV init scripts.</para></listitem> | |
770 | </varlistentry> | |
771 | ||
772 | <varlistentry> | |
773 | <term><varname>$SYSTEMD_SYSVRCND_PATH</varname></term> | |
774 | ||
775 | <listitem><para>Controls where systemd | |
776 | looks for SysV init script runlevel link | |
777 | farms.</para></listitem> | |
778 | </varlistentry> | |
779 | ||
780 | <varlistentry> | |
781 | <term><varname>$LISTEN_PID</varname></term> | |
782 | <term><varname>$LISTEN_FDS</varname></term> | |
783 | ||
784 | <listitem><para>Set by systemd for | |
785 | supervised processes during | |
786 | socket-based activation. See | |
787 | <citerefentry><refentrytitle>sd_listen_fds</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
788 | for more information. | |
789 | </para></listitem> | |
790 | </varlistentry> | |
791 | ||
792 | <varlistentry> | |
793 | <term><varname>$NOTIFY_SOCKET</varname></term> | |
794 | ||
795 | <listitem><para>Set by systemd for | |
796 | supervised processes for status and | |
797 | start-up completion notification. See | |
798 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
799 | for more information. | |
800 | </para></listitem> | |
801 | </varlistentry> | |
802 | </variablelist> | |
803 | </refsect1> | |
160cd5c9 | 804 | |
f3e219a2 LP |
805 | <refsect1> |
806 | <title>Kernel Command Line</title> | |
807 | ||
808 | <para>When run as system instance systemd parses a few kernel command line arguments:</para> | |
809 | ||
810 | <variablelist> | |
811 | <varlistentry> | |
812 | <term><varname>systemd.unit=</varname></term> | |
813 | ||
814 | <listitem><para>Overrides the unit to | |
815 | activate on boot. Defaults to | |
816 | <filename>default.target</filename>. This | |
817 | may be used to temporarily boot into a | |
818 | different boot unit, for example | |
819 | <filename>rescue.target</filename> or | |
820 | <filename>emergency.service</filename>. See | |
821 | <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
822 | for details about these | |
823 | units.</para></listitem> | |
824 | </varlistentry> | |
825 | ||
f3e219a2 LP |
826 | <varlistentry> |
827 | <term><varname>systemd.dump_core=</varname></term> | |
828 | ||
829 | <listitem><para>Takes a boolean | |
830 | argument. If <option>true</option> | |
831 | systemd dumps core when it | |
832 | crashes. Otherwise no core dump is | |
833 | created. Defaults to | |
834 | <option>true</option>.</para></listitem> | |
835 | </varlistentry> | |
836 | ||
837 | <varlistentry> | |
838 | <term><varname>systemd.crash_shell=</varname></term> | |
839 | ||
840 | <listitem><para>Takes a boolean | |
841 | argument. If <option>true</option> | |
842 | systemd spawns a shell when it | |
843 | crashes. Otherwise no core dump is | |
844 | created. Defaults to | |
845 | <option>false</option>, for security | |
846 | reasons, as the shell is not protected | |
847 | by any password | |
848 | authentication.</para></listitem> | |
849 | </varlistentry> | |
850 | ||
851 | <varlistentry> | |
852 | <term><varname>systemd.crash_chvt=</varname></term> | |
853 | ||
854 | <listitem><para>Takes an integer | |
855 | argument. If positive systemd | |
856 | activates the specified virtual | |
857 | terminal when it crashes. Defaults to | |
858 | <literal>-1</literal>.</para></listitem> | |
859 | </varlistentry> | |
860 | ||
69dd2852 LP |
861 | <varlistentry> |
862 | <term><varname>systemd.confirm_spawn=</varname></term> | |
863 | ||
864 | <listitem><para>Takes a boolean | |
865 | argument. If <option>true</option> | |
866 | asks for confirmation when spawning | |
867 | processes. Defaults to | |
868 | <option>false</option>.</para></listitem> | |
869 | </varlistentry> | |
870 | ||
f3e219a2 LP |
871 | <varlistentry> |
872 | <term><varname>systemd.show_status=</varname></term> | |
873 | ||
874 | <listitem><para>Takes a boolean | |
875 | argument. If <option>true</option> | |
876 | shows terse service status updates on | |
877 | the console during bootup. Defaults to | |
878 | <option>true</option>.</para></listitem> | |
879 | </varlistentry> | |
880 | ||
69dd2852 LP |
881 | <varlistentry> |
882 | <term><varname>systemd.sysv_console=</varname></term> | |
883 | ||
884 | <listitem><para>Takes a boolean | |
885 | argument. If <option>true</option> | |
886 | output of SysV init scripts will be | |
887 | directed to the console. Defaults to | |
888 | <option>true</option>, unless | |
889 | <option>quiet</option> is passed as | |
890 | kernel command line option in which | |
891 | case it defaults to | |
892 | <option>false</option>.</para></listitem> | |
893 | </varlistentry> | |
894 | ||
895 | <varlistentry> | |
896 | <term><varname>systemd.log_target=</varname></term> | |
897 | <term><varname>systemd.log_level=</varname></term> | |
898 | <term><varname>systemd.log_color=</varname></term> | |
899 | <term><varname>systemd.log_location=</varname></term> | |
900 | ||
901 | <listitem><para>Controls log output, | |
902 | with the same effect as the | |
903 | <varname>$SYSTEMD_LOG_TARGET</varname>, <varname>$SYSTEMD_LOG_LEVEL</varname>, <varname>$SYSTEMD_LOG_COLOR</varname>, <varname>$SYSTEMD_LOG_LOCATION</varname> | |
904 | environment variables described above.</para></listitem> | |
905 | </varlistentry> | |
906 | ||
f3e219a2 LP |
907 | </variablelist> |
908 | </refsect1> | |
909 | ||
2218198b LP |
910 | <refsect1> |
911 | <title>Sockets and FIFOs</title> | |
912 | ||
913 | <variablelist> | |
914 | <varlistentry> | |
915 | <term><filename>@/org/freedesktop/systemd1/notify</filename></term> | |
916 | ||
917 | <listitem><para>Daemon status | |
918 | notification socket. This is an AF_UNIX | |
919 | datagram socket in the Linux abstract | |
920 | namespace, and is used to implement | |
921 | the daemon notification logic as | |
922 | implemented by | |
923 | <citerefentry><refentrytitle>sd_notify</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para></listitem> | |
924 | ||
925 | </varlistentry> | |
926 | ||
927 | <varlistentry> | |
928 | <term><filename>@/org/freedesktop/systemd1/logger</filename></term> | |
929 | ||
930 | <listitem><para>Used internally by the | |
931 | <filename>systemd-logger.service</filename> | |
932 | unit to connect STDOUT and/or STDERR | |
933 | of spawned processes to | |
934 | <citerefentry><refentrytitle>syslog</refentrytitle><manvolnum>3</manvolnum></citerefentry> | |
935 | or the kernel log buffer. This is an | |
936 | AF_UNIX stream socket in the Linux | |
937 | abstract namespace.</para></listitem> | |
938 | </varlistentry> | |
939 | ||
940 | <varlistentry> | |
941 | <term><filename>@/org/freedesktop/systemd1/private</filename></term> | |
942 | ||
943 | <listitem><para>Used internally as | |
944 | communication channel between | |
945 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
946 | and the systemd process. This is an | |
947 | AF_UNIX stream socket in the Linux | |
948 | abstract namespace. This interface is | |
949 | private to systemd and should not be | |
950 | used in external | |
951 | projects.</para></listitem> | |
952 | </varlistentry> | |
953 | ||
954 | <varlistentry> | |
955 | <term><filename>/dev/initctl</filename></term> | |
956 | ||
957 | <listitem><para>Limited compatibility | |
958 | support for the SysV client interface, | |
959 | as implemented by the | |
960 | <filename>systemd-initctl.service</filename> | |
961 | unit. This is a named pipe in the file | |
962 | system. This interface is obsolete and | |
963 | should not be used in new | |
964 | applications.</para></listitem> | |
965 | </varlistentry> | |
966 | </variablelist> | |
9e632bf7 LP |
967 | </refsect1> |
968 | ||
9e632bf7 LP |
969 | <refsect1> |
970 | <title>See Also</title> | |
971 | <para> | |
7874bcd6 LP |
972 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
973 | <citerefentry><refentrytitle>systemadm</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
7874bcd6 | 974 | <citerefentry><refentrytitle>systemd-notify</refentrytitle><manvolnum>1</manvolnum></citerefentry>, |
9e632bf7 | 975 | <citerefentry><refentrytitle>daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
7874bcd6 LP |
976 | <citerefentry><refentrytitle>sd-daemon</refentrytitle><manvolnum>7</manvolnum></citerefentry>, |
977 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
978 | <citerefentry><refentrytitle>systemd.special</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
979 | <citerefentry><refentrytitle>pkg-config</refentrytitle><manvolnum>1</manvolnum></citerefentry> | |
9e632bf7 LP |
980 | </para> |
981 | </refsect1> | |
982 | ||
983 | </refentry> |