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11fcc3ab | 2 | <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" |
12b42c76 | 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 | |
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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 | |
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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. |
11fcc3ab | 19 | |
5430f7f2 | 20 | You should have received a copy of the GNU Lesser General Public License |
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21 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
22 | --> | |
23 | ||
24 | <refentry id="systemd.timer"> | |
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25 | <refentryinfo> |
26 | <title>systemd.timer</title> | |
27 | <productname>systemd</productname> | |
28 | ||
29 | <authorgroup> | |
30 | <author> | |
31 | <contrib>Developer</contrib> | |
32 | <firstname>Lennart</firstname> | |
33 | <surname>Poettering</surname> | |
34 | <email>lennart@poettering.net</email> | |
35 | </author> | |
36 | </authorgroup> | |
37 | </refentryinfo> | |
38 | ||
39 | <refmeta> | |
40 | <refentrytitle>systemd.timer</refentrytitle> | |
41 | <manvolnum>5</manvolnum> | |
42 | </refmeta> | |
43 | ||
44 | <refnamediv> | |
45 | <refname>systemd.timer</refname> | |
46 | <refpurpose>Timer unit configuration</refpurpose> | |
47 | </refnamediv> | |
48 | ||
49 | <refsynopsisdiv> | |
50 | <para><filename><replaceable>timer</replaceable>.timer</filename></para> | |
51 | </refsynopsisdiv> | |
52 | ||
53 | <refsect1> | |
54 | <title>Description</title> | |
55 | ||
56 | <para>A unit configuration file whose name ends in | |
57 | <literal>.timer</literal> encodes information about a timer | |
58 | controlled and supervised by systemd, for timer-based | |
59 | activation.</para> | |
60 | ||
61 | <para>This man page lists the configuration options specific to | |
62 | this unit type. See | |
63 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry> | |
64 | for the common options of all unit configuration files. The common | |
65 | configuration items are configured in the generic [Unit] and | |
66 | [Install] sections. The timer specific configuration options are | |
67 | configured in the [Timer] section.</para> | |
68 | ||
69 | <para>For each timer file, a matching unit file must exist, | |
70 | describing the unit to activate when the timer elapses. By | |
71 | default, a service by the same name as the timer (except for the | |
72 | suffix) is activated. Example: a timer file | |
73 | <filename>foo.timer</filename> activates a matching service | |
74 | <filename>foo.service</filename>. The unit to activate may be | |
75 | controlled by <varname>Unit=</varname> (see below).</para> | |
76 | ||
77 | <para>Unless <varname>DefaultDependencies=</varname> is set to | |
78 | <option>false</option>, all timer units will implicitly have | |
79 | dependencies of type <varname>Conflicts=</varname> and | |
80 | <varname>Before=</varname> on <filename>shutdown.target</filename> | |
81 | to ensure that they are stopped cleanly prior to system shutdown. | |
82 | Timer units with at least one <varname>OnCalendar=</varname> | |
83 | directive will have an additional <varname>After=</varname> | |
84 | dependency on <filename>timer-sync.target</filename> to avoid | |
85 | being started before the system clock has been correctly set. Only | |
86 | timer units involved with early boot or late system shutdown | |
87 | should disable the <varname>DefaultDependencies=</varname> | |
88 | option.</para> | |
89 | </refsect1> | |
90 | ||
91 | <refsect1> | |
92 | <title>Options</title> | |
93 | ||
94 | <para>Timer files must include a [Timer] section, which carries | |
95 | information about the timer it defines. The options specific to | |
96 | the [Timer] section of timer units are the following:</para> | |
97 | ||
98 | <variablelist class='unit-directives'> | |
99 | <varlistentry> | |
100 | <term><varname>OnActiveSec=</varname></term> | |
101 | <term><varname>OnBootSec=</varname></term> | |
102 | <term><varname>OnStartupSec=</varname></term> | |
103 | <term><varname>OnUnitActiveSec=</varname></term> | |
104 | <term><varname>OnUnitInactiveSec=</varname></term> | |
105 | ||
106 | <listitem><para>Defines monotonic timers relative to different | |
107 | starting points: <varname>OnActiveSec=</varname> defines a | |
108 | timer relative to the moment the timer itself is activated. | |
109 | <varname>OnBootSec=</varname> defines a timer relative to when | |
110 | the machine was booted up. <varname>OnStartupSec=</varname> | |
111 | defines a timer relative to when systemd was first started. | |
112 | <varname>OnUnitActiveSec=</varname> defines a timer relative | |
113 | to when the unit the timer is activating was last activated. | |
114 | <varname>OnUnitInactiveSec=</varname> defines a timer relative | |
115 | to when the unit the timer is activating was last | |
116 | deactivated.</para> | |
117 | ||
118 | <para>Multiple directives may be combined of the same and of | |
119 | different types. For example, by combining | |
120 | <varname>OnBootSec=</varname> and | |
121 | <varname>OnUnitActiveSec=</varname>, it is possible to define | |
122 | a timer that elapses in regular intervals and activates a | |
123 | specific service each time.</para> | |
124 | ||
125 | <para>The arguments to the directives are time spans | |
126 | configured in seconds. Example: "OnBootSec=50" means 50s after | |
127 | boot-up. The argument may also include time units. Example: | |
128 | "OnBootSec=5h 30min" means 5 hours and 30 minutes after | |
129 | boot-up. For details about the syntax of time spans, see | |
9905e698 | 130 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>.</para> |
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131 | |
132 | <para>If a timer configured with <varname>OnBootSec=</varname> | |
133 | or <varname>OnStartupSec=</varname> is already in the past | |
134 | when the timer unit is activated, it will immediately elapse | |
135 | and the configured unit is started. This is not the case for | |
136 | timers defined in the other directives.</para> | |
137 | ||
138 | <para>These are monotonic timers, independent of wall-clock | |
139 | time and timezones. If the computer is temporarily suspended, | |
140 | the monotonic clock stops too.</para> | |
141 | ||
142 | <para>If the empty string is assigned to any of these options, | |
143 | the list of timers is reset, and all prior assignments will | |
144 | have no effect.</para> | |
145 | ||
146 | <para>Note that timers do not necessarily expire at the | |
147 | precise time configured with these settings, as they are | |
148 | subject to the <varname>AccuracySec=</varname> setting | |
149 | below.</para></listitem> | |
150 | ||
151 | </varlistentry> | |
152 | ||
153 | <varlistentry> | |
154 | <term><varname>OnCalendar=</varname></term> | |
155 | ||
156 | <listitem><para>Defines realtime (i.e. wallclock) timers with | |
157 | calendar event expressions. See | |
158 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry> | |
159 | for more information on the syntax of calendar event | |
160 | expressions. Otherwise, the semantics are similar to | |
161 | <varname>OnActiveSec=</varname> and related settings.</para> | |
162 | ||
163 | <para>Note that timers do not necessarily expire at the | |
164 | precise time configured with this setting, as it is subject to | |
165 | the <varname>AccuracySec=</varname> setting | |
166 | below.</para></listitem> | |
167 | </varlistentry> | |
168 | ||
169 | <varlistentry> | |
170 | <term><varname>AccuracySec=</varname></term> | |
171 | ||
172 | <listitem><para>Specify the accuracy the timer shall elapse | |
173 | with. Defaults to 1min. The timer is scheduled to elapse | |
174 | within a time window starting with the time specified in | |
175 | <varname>OnCalendar=</varname>, | |
176 | <varname>OnActiveSec=</varname>, | |
177 | <varname>OnBootSec=</varname>, | |
178 | <varname>OnStartupSec=</varname>, | |
179 | <varname>OnUnitActiveSec=</varname> or | |
180 | <varname>OnUnitInactiveSec=</varname> and ending the time | |
181 | configured with <varname>AccuracySec=</varname> later. Within | |
182 | this time window, the expiry time will be placed at a | |
183 | host-specific, randomized but stable position that is | |
184 | synchronized between all local timer units. This is done in | |
185 | order to distribute the wake-up time in networked | |
186 | installations, as well as optimizing power consumption to | |
187 | suppress unnecessary CPU wake-ups. To get best accuracy, set | |
188 | this option to 1us. Note that the timer is still subject to | |
189 | the timer slack configured via | |
190 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s | |
191 | <varname>TimerSlackNSec=</varname> setting. See | |
192 | <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
193 | for details. To optimize power consumption, make sure to set | |
194 | this value as high as possible and as low as | |
195 | necessary.</para></listitem> | |
196 | </varlistentry> | |
197 | <varlistentry> | |
198 | <term><varname>Unit=</varname></term> | |
199 | ||
200 | <listitem><para>The unit to activate when this timer elapses. | |
201 | The argument is a unit name, whose suffix is not | |
202 | <literal>.timer</literal>. If not specified, this value | |
203 | defaults to a service that has the same name as the timer | |
204 | unit, except for the suffix. (See above.) It is recommended | |
205 | that the unit name that is activated and the unit name of the | |
206 | timer unit are named identically, except for the | |
207 | suffix.</para></listitem> | |
208 | </varlistentry> | |
209 | ||
210 | ||
211 | <varlistentry> | |
212 | <term><varname>Persistent=</varname></term> | |
213 | ||
214 | <listitem><para>Takes a boolean argument. If true, the time | |
215 | when the service unit was last triggered is stored on disk. | |
216 | When the timer is activated, the service unit is triggered | |
217 | immediately if it would have been triggered at least once | |
218 | during the time when the timer was inactive. This is useful to | |
219 | catch up on missed runs of the service when the machine was | |
220 | off. Note that this setting only has an effect on timers | |
221 | configured with <varname>OnCalendar=</varname>. | |
222 | </para></listitem> | |
223 | </varlistentry> | |
224 | ||
225 | <varlistentry> | |
226 | <term><varname>WakeSystem=</varname></term> | |
227 | ||
228 | <listitem><para>Takes a boolean argument. If true, an elapsing | |
229 | timer will cause the system to resume from suspend, should it | |
230 | be suspended and if the system supports this. Note that this | |
231 | option will only make sure the system resumes on the | |
232 | appropriate times, it will not take care of suspending it | |
233 | again after any work that is to be done is finished. Defaults | |
234 | to <varname>false</varname>.</para></listitem> | |
235 | </varlistentry> | |
236 | </variablelist> | |
237 | </refsect1> | |
238 | ||
239 | <refsect1> | |
240 | <title>See Also</title> | |
241 | <para> | |
242 | <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
243 | <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>, | |
244 | <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
245 | <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
246 | <citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
247 | <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>, | |
248 | <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>, | |
249 | <citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry> | |
250 | </para> | |
251 | </refsect1> | |
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252 | |
253 | </refentry> |