1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
|
<?xml version='1.0'?> <!--*-nxml-*-->
<?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
<!--
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
-->
<refentry id="systemd.timer">
<refentryinfo>
<title>systemd.timer</title>
<productname>systemd</productname>
<authorgroup>
<author>
<contrib>Developer</contrib>
<firstname>Lennart</firstname>
<surname>Poettering</surname>
<email>lennart@poettering.net</email>
</author>
</authorgroup>
</refentryinfo>
<refmeta>
<refentrytitle>systemd.timer</refentrytitle>
<manvolnum>5</manvolnum>
</refmeta>
<refnamediv>
<refname>systemd.timer</refname>
<refpurpose>Timer unit configuration</refpurpose>
</refnamediv>
<refsynopsisdiv>
<para><filename><replaceable>timer</replaceable>.timer</filename></para>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>A unit configuration file whose name ends in
<literal>.timer</literal> encodes information about
a timer controlled and supervised by systemd, for
timer-based activation.</para>
<para>This man page lists the configuration options
specific to this unit type. See
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
for the common options of all unit configuration
files. The common configuration items are configured
in the generic [Unit] and [Install] sections. The
timer specific configuration options are configured in
the [Timer] section.</para>
<para>For each timer file, a matching unit file must
exist, describing the unit to activate when the timer
elapses. By default, a service by the same name as the
timer (except for the suffix) is activated. Example: a
timer file <filename>foo.timer</filename> activates a
matching service <filename>foo.service</filename>. The
unit to activate may be controlled by
<varname>Unit=</varname> (see below).</para>
<para>Unless <varname>DefaultDependencies=</varname>
is set to <option>false</option>, timer units will
implicitly have dependencies of type
<varname>Conflicts=</varname> and
<varname>Before=</varname> on
<filename>shutdown.target</filename>. These ensure
that timer units are stopped cleanly prior to system
shutdown. Only timer units involved with early boot or
late system shutdown should disable this
option.</para>
</refsect1>
<refsect1>
<title>Options</title>
<para>Timer files must include a [Timer] section,
which carries information about the timer it
defines. The options specific to the [Timer] section
of timer units are the following:</para>
<variablelist class='unit-directives'>
<varlistentry>
<term><varname>OnActiveSec=</varname></term>
<term><varname>OnBootSec=</varname></term>
<term><varname>OnStartupSec=</varname></term>
<term><varname>OnUnitActiveSec=</varname></term>
<term><varname>OnUnitInactiveSec=</varname></term>
<listitem><para>Defines monotonic timers
relative to different starting points:
<varname>OnActiveSec=</varname> defines a
timer relative to the moment the timer
itself is
activated. <varname>OnBootSec=</varname>
defines a timer relative to when the
machine was booted
up. <varname>OnStartupSec=</varname>
defines a timer relative to when
systemd was first
started. <varname>OnUnitActiveSec=</varname>
defines a timer relative to when the
unit the timer is activating was last
activated. <varname>OnUnitInactiveSec=</varname>
defines a timer relative to when the
unit the timer is activating was last
deactivated.</para>
<para>Multiple directives may be
combined of the same and of different
types. For example, by combining
<varname>OnBootSec=</varname> and
<varname>OnUnitActiveSec=</varname>, it is
possible to define a timer that
elapses in regular intervals and
activates a specific service each
time.</para>
<para>The arguments to the directives
are time spans configured in
seconds. Example: "OnBootSec=50" means
50s after boot-up. The argument may
also include time units. Example:
"OnBootSec=5h 30min" means 5 hours and
30 minutes after boot-up. For details
about the syntax of time spans, see
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
<para>If a timer configured with
<varname>OnBootSec=</varname> or
<varname>OnStartupSec=</varname> is
already in the past when the timer
unit is activated, it will immediately
elapse and the configured unit is
started. This is not the case for
timers defined in the other
directives.</para>
<para>These are monotonic timers,
independent of wall-clock time and timezones. If the
computer is temporarily suspended, the
monotonic clock stops too.</para>
<para>If the empty string is assigned
to any of these options, the list of
timers is reset, and all prior
assignments will have no
effect.</para>
<para>Note that timers do not
necessarily expire at the precise
time configured with these settings,
as they are subject to the
<varname>AccuracySec=</varname>
setting below.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>OnCalendar=</varname></term>
<listitem><para>Defines realtime
(i.e. wallclock) timers with calendar
event expressions. See
<citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>
for more information on the syntax of
calendar event expressions. Otherwise,
the semantics are similar to
<varname>OnActiveSec=</varname> and
related settings.</para>
<para>Note that timers do not
necessarily expire at the precise
time configured with this setting,
as it is subject to the
<varname>AccuracySec=</varname>
setting below.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>AccuracySec=</varname></term>
<listitem><para>Specify the accuracy
the timer shall elapse with. Defaults
to 1min. The timer is scheduled to
elapse within a time window starting
with the time specified in
<varname>OnCalendar=</varname>,
<varname>OnActiveSec=</varname>,
<varname>OnBootSec=</varname>,
<varname>OnStartupSec=</varname>,
<varname>OnUnitActiveSec=</varname> or
<varname>OnUnitInactiveSec=</varname>
and ending the time configured with
<varname>AccuracySec=</varname>
later. Within this time window, the
expiry time will be placed at a
host-specific, randomized but stable
position that is synchronized between
all local timer units. This is done in
order to distribute the wake-up time
in networked installations, as well as
optimizing power consumption to
suppress unnecessary CPU wake-ups. To
get best accuracy, set this option to
1us. Note that the timer is still
subject to the timer slack configured
via
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>'s
<varname>TimerSlackNSec=</varname>
setting. See
<citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
for details. To optimize power
consumption, make sure to set this
value as high as possible and as low
as necessary.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>Unit=</varname></term>
<listitem><para>The unit to activate
when this timer elapses. The argument is a
unit name, whose suffix is not
<literal>.timer</literal>. If not
specified, this value defaults to a
service that has the same name as the
timer unit, except for the
suffix. (See above.) It is recommended
that the unit name that is activated
and the unit name of the timer unit
are named identically, except for the
suffix.</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>Persistent=</varname></term>
<listitem><para>Takes a boolean
argument. If true, the time when the
service unit was last triggered is
stored on disk. When the timer is
activated, the service unit is
triggered immediately if it would have
been triggered at least once during
the time when the timer was inactive.
This is useful to catch up on missed
runs of the service when the machine
was off. Note that this setting only
has an effect on timers configured
with <varname>OnCalendar=</varname>.
</para></listitem>
</varlistentry>
<varlistentry>
<term><varname>WakeSystem=</varname></term>
<listitem><para>Takes a boolean
argument. If true, an elapsing timer
will cause the system to resume from
suspend, should it be suspended and if
the system supports this. Note that
this option will only make sure the
system resumes on the appropriate
times, it will not take care of
suspending it again after any work
that is to be done is
finished. Defaults to
<varname>false</varname>.</para></listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>See Also</title>
<para>
<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.time</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>,
<citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
<citerefentry><refentrytitle>prctl</refentrytitle><manvolnum>2</manvolnum></citerefentry>
</para>
</refsect1>
</refentry>
|
