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-<?xml version='1.0'?> <!--*-nxml-*-->
-<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
- "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
-
-<!--
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-
- Copyright 2010 Lennart Poettering
-
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--->
-
-<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>, all timer units will implicitly have
- dependencies of type <varname>Conflicts=</varname> and
- <varname>Before=</varname> on <filename>shutdown.target</filename>
- to ensure that they are stopped cleanly prior to system shutdown.
- Timer units with at least one <varname>OnCalendar=</varname>
- directive will have an additional <varname>After=</varname>
- dependency on <filename>timer-sync.target</filename> to avoid
- being started before the system clock has been correctly set. Only
- timer units involved with early boot or late system shutdown
- should disable the <varname>DefaultDependencies=</varname>
- 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>1</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>
~ianmdlvl / elogind.git / blobdiff