-<?xml version='1.0'?> <!--*- Mode: nxml; nxml-child-indent: 2; indent-tabs-mode: nil -*-->
+<?xml version='1.0'?>
<!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.
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- systemd is distributed in the hope that it will be useful, but
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- Lesser General Public License for more details.
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- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
+ SPDX-License-Identifier: LGPL-2.1+
-->
<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>
<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>Note that in case the unit to activate is already active at the time the timer elapses it is not restarted,
+ but simply left running. There is no concept of spawning new service instances in this case. Due to this, services
+ with <varname>RemainAfterExit=</varname> set (which stay around continuously even after the service's main process
+ exited) are usually not suitable for activation via repetitive timers, as they will only be activated once, and
+ then stay around forever.</para>
+ </refsect1>
+
+ <refsect1>
+ <title>Implicit Dependencies</title>
+
+ <para>The following dependencies are implicitly added:</para>
+
+ <itemizedlist>
+ <listitem><para>Timer units automatically gain a <varname>Before=</varname>
+ dependency on the service they are supposed to activate.</para></listitem>
+ </itemizedlist>
</refsect1>
<refsect1>
<title>Automatic Dependencies</title>
- <para>Timer units automatically gain a <varname>Before=</varname>
- dependency on the service they are supposed to activate.</para>
-
- <para>Unless <varname>DefaultDependencies=</varname> in the <literal>[Unit]</literal> section is set to
- <option>false</option>, all timer units will implicitly have dependencies of type <varname>Requires=</varname> and
- <varname>After=</varname> on <filename>sysinit.target</filename>, a dependency of type <varname>Before=</varname>
- on <filename>timers.target</filename>, as well as <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>
+ <refsect2>
+ <title>Implicit Dependencies</title>
+
+ <para>There are no implicit dependencies for timer units.</para>
+ </refsect2>
+
+ <refsect2>
+ <title>Default Dependencies</title>
+
+ <para>The following dependencies are added unless <varname>DefaultDependencies=no</varname> is set:</para>
+
+ <itemizedlist>
+ <listitem><para>Timer units will automatically have dependencies of type <varname>Requires=</varname> and
+ <varname>After=</varname> on <filename>sysinit.target</filename>, a dependency of type <varname>Before=</varname>
+ on <filename>timers.target</filename>, as well as <varname>Conflicts=</varname> and <varname>Before=</varname> on
+ <filename>shutdown.target</filename> to ensure that they are stopped cleanly prior to system shutdown. Only timer
+ units involved with early boot or late system shutdown should disable the
+ <varname>DefaultDependencies=</varname> option.</para></listitem>
+
+ <listitem><para>Timer units
+ with at least one <varname>OnCalendar=</varname> directive will have an additional <varname>After=</varname>
+ dependency on <filename>time-sync.target</filename> to avoid being started before the system clock has been
+ correctly set.</para></listitem>
+ </itemizedlist>
+ </refsect2>
</refsect1>
<refsect1>
<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>
+ below.</para>
+
+ <para>May be specified more than once.</para></listitem>
</varlistentry>
<varlistentry>
suffix.</para></listitem>
</varlistentry>
-
<varlistentry>
<term><varname>Persistent=</varname></term>
starting a timer unit that only elapses once: if
<varname>RemainAfterElapse=</varname> is on, it will not be
started again, and is guaranteed to elapse only once. However,
- if <varname>RemainAfterLeapse=</varname> is off, it might be
+ if <varname>RemainAfterElapse=</varname> is off, it might be
started again if it is already elapsed, and thus be triggered
multiple times. Defaults to
<varname>yes</varname>.</para></listitem>