Adding upstream version 241.upstream/241upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 308 insertions, 0 deletions

diff --git a/man/systemd.timer.xml b/man/systemd.timer.xml
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+<?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">
+
+<!--
+  SPDX-License-Identifier: LGPL-2.1+
+-->
+
+<refentry id="systemd.timer">
+  <refentryinfo>
+    <title>systemd.timer</title>
+    <productname>systemd</productname>
+  </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>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>Automatic Dependencies</title>
+
+    <refsect2>
+      <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>
+    </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>
+    <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.time</refentrytitle><manvolnum>7</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>
+
+       <para>May be specified more than once.</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 optimize 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>RandomizedDelaySec=</varname></term>
+
+        <listitem><para>Delay the timer by a randomly selected, evenly
+        distributed amount of time between 0 and the specified time
+        value. Defaults to 0, indicating that no randomized delay
+        shall be applied. Each timer unit will determine this delay
+        randomly before each iteration, and the delay will simply be
+        added on top of the next determined elapsing time. This is
+        useful to stretch dispatching of similarly configured timer
+        events over a certain amount time, to avoid that they all fire
+        at the same time, possibly resulting in resource
+        congestion. Note the relation to
+        <varname>AccuracySec=</varname> above: the latter allows the
+        service manager to coalesce timer events within a specified
+        time range in order to minimize wakeups, the former does the
+        opposite: it stretches timer events over a time range, to make
+        it unlikely that they fire simultaneously. If
+        <varname>RandomizedDelaySec=</varname> and
+        <varname>AccuracySec=</varname> are used in conjunction, first
+        the randomized delay is added, and then the result is
+        possibly further shifted to coalesce it with other timer
+        events happening on the system. As mentioned above
+        <varname>AccuracySec=</varname> defaults to 1min and
+        <varname>RandomizedDelaySec=</varname> to 0, thus encouraging
+        coalescing of timer events. In order to optimally stretch
+        timer events over a certain range of time, make sure to set
+        <varname>RandomizedDelaySec=</varname> to a higher value, and
+        <varname>AccuracySec=1us</varname>.</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>. Defaults
+        to <varname>false</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>
+
+      <varlistentry>
+        <term><varname>RemainAfterElapse=</varname></term>
+
+        <listitem><para>Takes a boolean argument. If true, an elapsed
+        timer will stay loaded, and its state remains queriable. If
+        false, an elapsed timer unit that cannot elapse anymore is
+        unloaded. Turning this off is particularly useful for
+        transient timer units that shall disappear after they first
+        elapse. Note that this setting has an effect on repeatedly
+        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>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>
+      </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>