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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>systemd.swap</filename></para>

</refsynopsisdiv>

<refsect1>

<title>Description</title>

<para>A unit configuration file whose name ends in

<filename>.swap</filename> 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>Swap units must be named after the devices

(resp. files) they control. Example: the swap device

<filename>/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 (resp. 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>. The

options specific to the [Swap] section of swap units

are the following:</para>

<variablelist>

<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

SIGTERM, and after another delay of

this time with SIGKILL. (See

<option>KillMode=</option> below.)

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

90s.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>KillMode=</varname></term>

<listitem><para>Specifies how

processes of this swap shall be

killed. One of

<option>control-group</option>,

<option>process</option>,

<option>none</option>.</para>

<para>This option is mostly equivalent

to the <option>KillMode=</option>

option of service files. See

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

for details.</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>KillSignal=</varname></term>

<listitem><para>Specifies which signal

to use when killing a process of this

swap. Defaults to SIGTERM.

</para></listitem>

</varlistentry>

<varlistentry>

<term><varname>SendSIGKILL=</varname></term>

<listitem><para>Specifies whether to

send SIGKILL to remaining processes

after a timeout, if the normal

shutdown procedure left processes of

the swap around. Takes a boolean

value. Defaults to "yes".

</para></listitem>

</varlistentry>

</variablelist>

</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.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>

</para>

</refsect1>

</refentry>