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3 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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24
25 <refentry id="systemd.timer">
26         <refentryinfo>
27                 <title>systemd.timer</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.timer</refentrytitle>
42                 <manvolnum>5</manvolnum>
43         </refmeta>
44
45         <refnamediv>
46                 <refname>systemd.timer</refname>
47                 <refpurpose>systemd timer configuration files</refpurpose>
48         </refnamediv>
49
50         <refsynopsisdiv>
51                 <para><filename>systemd.timer</filename></para>
52         </refsynopsisdiv>
53
54         <refsect1>
55                 <title>Description</title>
56
57                 <para>A unit configuration file whose name ends in
58                 <filename>.timer</filename> encodes information about
59                 a timer controlled and supervised by systemd, for
60                 timer-based activation.</para>
61
62                 <para>This man page lists the configuration options
63                 specific to this unit type. See
64                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
65                 for the common options of all unit configuration
66                 files. The common configuration items are configured
67                 in the generic [Unit] and [Install] sections. The
68                 timer specific configuration options are configured in
69                 the [Timer] section.</para>
70
71                 <para>For each timer file, a matching unit file must
72                 exist, describing the unit to activate when the timer
73                 elapses. By default, a service by the same name as the
74                 timer (except for the suffix) is activated. Example: a
75                 timer file <filename>foo.timer</filename> activates a
76                 matching service <filename>foo.service</filename>. The
77                 unit to activate may be controlled by
78                 <varname>Unit=</varname> (see below).</para>
79
80                 <para>Unless <varname>DefaultDependencies=</varname>
81                 is set to <option>false</option>, timer units will
82                 implicitly have dependencies of type
83                 <varname>Conflicts=</varname> and
84                 <varname>Before=</varname> on
85                 <filename>shutdown.target</filename>. These ensure
86                 that timer units are stopped cleanly prior to system
87                 shutdown. Only timer units involved with early boot or
88                 late system shutdown should disable this
89                 option.</para>
90         </refsect1>
91
92         <refsect1>
93                 <title>Options</title>
94
95                 <para>Timer files must include a [Timer] section,
96                 which carries information about the timer it
97                 defines. The options specific to the [Timer] section
98                 of timer units are the following:</para>
99
100                 <variablelist>
101                         <varlistentry>
102                                 <term><varname>OnActiveSec=</varname></term>
103                                 <term><varname>OnBootSec=</varname></term>
104                                 <term><varname>OnStartupSec=</varname></term>
105                                 <term><varname>OnUnitActiveSec=</varname></term>
106                                 <term><varname>OnUnitInactiveSec=</varname></term>
107
108                                 <listitem><para>Defines timers
109                                 relative to different starting points:
110                                 <varname>OnActiveSec=</varname> defines a
111                                 timer relative to the moment the timer
112                                 itself is
113                                 activated. <varname>OnBootSec=</varname>
114                                 defines a timer relative to when the
115                                 machine was booted
116                                 up. <varname>OnStartupSec=</varname>
117                                 defines a timer relative to when
118                                 systemd was
119                                 started. <varname>OnUnitActiveSec=</varname>
120                                 defines a timer relative to when the
121                                 unit the timer is activating was last
122                                 activated. <varname>OnUnitInactiveSec=</varname>
123                                 defines a timer relative to when the
124                                 unit the timer is activating was last
125                                 deactivated.</para>
126
127                                 <para>Multiple directives may be
128                                 combined of the same and of different
129                                 types. For example, by combining
130                                 <varname>OnBootSec=</varname> and
131                                 <varname>OnUnitActiveSec=</varname> it is
132                                 possible to define a timer that
133                                 elapses in regular intervals and
134                                 activates a specific service each
135                                 time.</para>
136
137                                 <para>The arguments to the directives
138                                 are time spans configured in
139                                 seconds. Example: "OnBootSec=50" means
140                                 50s after boot-up. The argument may
141                                 also include time units. Example:
142                                 "OnBootSec=5h 30min" means 5 hours and 30
143                                 minutes after boot-up. For details
144                                 about the syntax of time spans see
145                                 <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
146
147                                 <para>If a timer configured with
148                                 <varname>OnBootSec=</varname> or
149                                 <varname>OnStartupSec=</varname> is
150                                 already in the past when the timer
151                                 unit is activated, it will immediately
152                                 elapse and the configured unit is
153                                 started. This is not the case for
154                                 timers defined in the other
155                                 directives.</para></listitem>
156
157                                 <para>These are monotonic timers,
158                                 independent of wall-clock time and timezones. If the
159                                 computer is temporarily suspended, the
160                                 monotonic clock stops too.</para>
161
162                         </varlistentry>
163                         <varlistentry>
164                                 <term><varname>Unit=</varname></term>
165
166                                 <listitem><para>The unit to activate
167                                 when this timer elapses. The argument is a
168                                 unit name, whose suffix is not
169                                 <filename>.timer</filename>. If not
170                                 specified, this value defaults to a
171                                 service that has the same name as the
172                                 timer unit, except for the
173                                 suffix. (See above.) It is recommended
174                                 that the unit name that is activated
175                                 and the unit name of the timer unit
176                                 are named identically, except for the
177                                 suffix.</para></listitem>
178                         </varlistentry>
179                 </variablelist>
180         </refsect1>
181
182         <refsect1>
183                   <title>See Also</title>
184                   <para>
185                           <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
186                           <citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
187                           <citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
188                           <citerefentry><refentrytitle>systemd.service</refentrytitle><manvolnum>5</manvolnum></citerefentry>
189                   </para>
190         </refsect1>
191
192 </refentry>