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<refentry id="systemd.swap">

<refentryinfo>

<title>systemd.swap</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.swap</refentrytitle>

<manvolnum>5</manvolnum>

</refmeta>

<refnamediv>

<refname>systemd.swap</refname>

<refpurpose>Swap unit configuration</refpurpose>

</refnamediv>

<refsynopsisdiv>

<para><filename><replaceable>swap</replaceable>.swap</filename></para>

</refsynopsisdiv>

<refsect1>

<title>Description</title>

<para>A unit configuration file whose name ends in

<literal>.swap</literal> encodes information about a

swap device or file for memory paging controlled and

supervised by systemd.</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 swap

specific configuration options are configured in the

[Swap] section.</para>

<para>Additional options are listed in

<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

which define the execution environment the

<citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>

binary is executed in, and in

<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

which define the way the processes are

terminated, and in

<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

which configure resource control settings for the

processes of the service.</para>

<para>Swap units must be named after the devices

or files they control. Example: the swap device

<filename noindex='true'>/dev/sda5</filename> must be configured in a

unit file <filename>dev-sda5.swap</filename>. For

details about the escaping logic used to convert a

file system path to a unit name see

<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>

<para>All swap units automatically get the appropriate

dependencies on the devices or on the mount points

of the files they are activated from.</para>

<para>Swap units with

<varname>DefaultDependencies=</varname> enabled

implicitly acquire a conflicting dependency to

<filename>umount.target</filename> so that they are

deactivated at shutdown.</para>

</refsect1>

<refsect1>

<title><filename>fstab</filename></title>

<para>Swap units may either be configured via unit

files, or via <filename>/etc/fstab</filename> (see

<citerefentry><refentrytitle>fstab</refentrytitle><manvolnum>5</manvolnum></citerefentry>

for details). Swaps listed in

<filename>/etc/fstab</filename> will be converted into

native units dynamically at boot and when the

configuration of the system manager is

reloaded. See

<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>

for details about the conversion.</para>

<para>If a swap device or file is configured in both

<filename>/etc/fstab</filename> and a unit file, the

configuration in the latter takes precedence.</para>

<para>Unless the <option>noauto</option> option is set

for them all swap units configured in

<filename>/etc/fstab</filename> are also added as

requirements to <filename>swap.target</filename>, so

that they are waited for and activated during

boot.</para>

</refsect1>

<refsect1>

<title>Options</title>

<para>Swap files must include a [Swap] section, which

carries information about the swap device it

supervises. A number of options that may be used in

this section are shared with other unit types. These

options are documented in

<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>

and

<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>. The

options specific to the [Swap] section of swap units

are the following:</para>

<variablelist class='unit-directives'>

<varlistentry>

<term><varname>What=</varname></term>

<listitem><para>Takes an absolute path

of a device node or file to use for

paging. See

<citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>

for details. If this refers to a

device node, a dependency on the

respective device unit is

automatically created. (See

<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>

for more information.) If this refers

to a file, a dependency on the

respective mount unit is automatically

created. (See

<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>

for more information.) This option is

mandatory.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>Priority=</varname></term>

<listitem><para>Swap priority to use

when activating the swap device or

file. This takes an integer. This

setting is optional.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>TimeoutSec=</varname></term>

<listitem><para>Configures the time to

wait for the swapon command to

finish. If a command does not exit

within the configured time, the swap

will be considered failed and be shut

down again. All commands still running

will be terminated forcibly via

<constant>SIGTERM</constant>, and after another delay of

this time with <constant>SIGKILL</constant>. (See

<option>KillMode=</option> in

<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>.)

Takes a unit-less value in seconds, or

a time span value such as "5min

20s". Pass 0 to disable the timeout

logic. Defaults to <varname>TimeoutStartSec=</varname> in

manager configuration file.</para></listitem>

</varlistentry>

</variablelist>

<para>Check

<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>

and

<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>

for more settings.</para>

</refsect1>

<refsect1>

<title>See Also</title>

<para>

<citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemctl</refentrytitle><manvolnum>8</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.unit</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.exec</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.kill</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.resource-control</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.device</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.mount</refentrytitle><manvolnum>5</manvolnum></citerefentry>,

<citerefentry><refentrytitle>swapon</refentrytitle><manvolnum>8</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd-fstab-generator</refentrytitle><manvolnum>8</manvolnum></citerefentry>,

<citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>

</para>

</refsect1>

</refentry>