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260 lines
14 KiB
XML
260 lines
14 KiB
XML
<?xml version='1.0'?> <!--*-nxml-*-->
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<?xml-stylesheet type="text/xsl" href="http://docbook.sourceforge.net/release/xsl/current/xhtml/docbook.xsl"?>
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<!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
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<!--
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This file is part of systemd.
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Copyright 2010 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(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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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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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
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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-->
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<refentry id="systemd.swap">
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<refentryinfo>
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<title>systemd.swap</title>
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<productname>systemd</productname>
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<authorgroup>
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<author>
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<contrib>Developer</contrib>
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<firstname>Lennart</firstname>
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<surname>Poettering</surname>
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<email>lennart@poettering.net</email>
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</author>
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</authorgroup>
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</refentryinfo>
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<refmeta>
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<refentrytitle>systemd.swap</refentrytitle>
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<manvolnum>5</manvolnum>
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</refmeta>
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<refnamediv>
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<refname>systemd.swap</refname>
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<refpurpose>Swap unit configuration</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<para><filename><replaceable>swap</replaceable>.swap</filename></para>
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</refsynopsisdiv>
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<refsect1>
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<title>Description</title>
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<para>A unit configuration file whose name ends in
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<literal>.swap</literal> encodes information about a
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swap device or file for memory paging controlled and
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supervised by systemd.</para>
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<para>This man page lists the configuration options
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specific to this unit type. See
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for the common options of all unit configuration
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files. The common configuration items are configured
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in the generic [Unit] and [Install] sections. The swap
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specific configuration options are configured in the
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[Swap] section.</para>
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<para>Additional options are listed in
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<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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which define the execution environment the
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<citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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binary is executed in, and in
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<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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which define the way the processes are
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terminated, and in
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<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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which configure resource control settings for the
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processes of the service.</para>
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<para>Swap units must be named after the devices
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or files they control. Example: the swap device
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<filename noindex='true'>/dev/sda5</filename> must be configured in a
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unit file <filename>dev-sda5.swap</filename>. For
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details about the escaping logic used to convert a
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file system path to a unit name, see
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
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<para>All swap units automatically get the appropriate
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dependencies on the devices or on the mount points
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of the files they are activated from.</para>
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<para>Swap units with
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<varname>DefaultDependencies=</varname> enabled
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implicitly acquire a conflicting dependency to
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<filename>umount.target</filename> so that they are
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deactivated at shutdown.</para>
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</refsect1>
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<refsect1>
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<title><filename>fstab</filename></title>
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<para>Swap units may either be configured via unit
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files, or via <filename>/etc/fstab</filename> (see
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<citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for details). Swaps listed in
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<filename>/etc/fstab</filename> will be converted into
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native units dynamically at boot and when the
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configuration of the system manager is
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reloaded. See
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<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for details about the conversion.</para>
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<para>If a swap device or file is configured in both
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<filename>/etc/fstab</filename> and a unit file, the
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configuration in the latter takes precedence.</para>
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<para>When reading <filename>/etc/fstab</filename> a
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few special options are understood by systemd which
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influence how dependencies are created for swap
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units.</para>
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<variablelist class='fstab-options'>
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<varlistentry>
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<term><option>noauto</option></term>
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<term><option>auto</option></term>
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<listitem><para>With <option>noauto</option> the
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swap unit will not be added as a dependency for
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<filename>swap.target</filename>. This means that
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it will not be activated automatically during
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boot, unless it is pulled in by some other
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unit. Option <option>auto</option> has the
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opposite meaning and is the default.</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><option>nofail</option></term>
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<listitem><para>With <option>nofail</option> the
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swap unit will be only wanted, not required by
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<filename>swap.target</filename>. This means that
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the boot will continue even if this swap device is
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not activated successfully.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Options</title>
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<para>Swap files must include a [Swap] section, which
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carries information about the swap device it
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supervises. A number of options that may be used in
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this section are shared with other unit types. These
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options are documented in
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<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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and
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<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The
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options specific to the [Swap] section of swap units
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are the following:</para>
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<variablelist class='unit-directives'>
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<varlistentry>
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<term><varname>What=</varname></term>
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<listitem><para>Takes an absolute path
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of a device node or file to use for
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paging. See
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<citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for details. If this refers to a
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device node, a dependency on the
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respective device unit is
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automatically created. (See
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<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for more information.) If this refers
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to a file, a dependency on the
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respective mount unit is automatically
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created. (See
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<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for more information.) This option is
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mandatory.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Priority=</varname></term>
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<listitem><para>Swap priority to use
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when activating the swap device or
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file. This takes an integer. This
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setting is optional.</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>Options=</varname></term>
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<listitem><para>May contain an option
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string for the swap device. This may
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be used for controlling discard
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options among other functionality, if
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the swap backing device supports the
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discard or trim operation. (See
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<citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>
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for more information.)
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</para></listitem>
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</varlistentry>
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<varlistentry>
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<term><varname>TimeoutSec=</varname></term>
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<listitem><para>Configures the time to
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wait for the swapon command to
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finish. If a command does not exit
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within the configured time, the swap
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will be considered failed and be shut
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down again. All commands still running
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will be terminated forcibly via
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<constant>SIGTERM</constant>, and after another delay of
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this time with <constant>SIGKILL</constant>. (See
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<option>KillMode=</option> in
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<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.)
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Takes a unit-less value in seconds, or
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a time span value such as "5min
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20s". Pass <literal>0</literal> to disable the timeout
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logic. Defaults to <varname>DefaultTimeoutStartSec=</varname> from the
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manager configuration file
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(see <citerefentry><refentrytitle>systemd-system.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>).
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</para></listitem>
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</varlistentry>
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</variablelist>
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<para>Check
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<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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and
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<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>
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for more settings.</para>
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</refsect1>
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<refsect1>
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<title>See Also</title>
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<para>
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<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,
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<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
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</para>
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</refsect1>
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</refentry>
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