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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 > systemd swap configuration files</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>
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<para > Swap units must be named after the devices
(resp. files) they control. Example: the swap device
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<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>
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<para > All swap units automatically get the appropriate
dependencies on the devices (resp. on the mount points
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of the files) they are activated from.</para>
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<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>
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</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).</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>
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<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>
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</refsect1>
<refsect1 >
<title > Options</title>
<para > Swap files must include a [Swap] section, which
carries information about the swap device it
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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>
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<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
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device node, a dependency on the
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respective device unit is
automatically created. (See
<citerefentry > <refentrytitle > systemd.device</refentrytitle> <manvolnum > 5</manvolnum> </citerefentry>
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
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>
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<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
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90s.</para> </listitem>
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</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>
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<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>
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</variablelist>
</refsect1>
<refsect1 >
<title > See Also</title>
<para >
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<citerefentry > <refentrytitle > systemd</refentrytitle> <manvolnum > 1</manvolnum> </citerefentry> ,
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<citerefentry > <refentrytitle > systemctl</refentrytitle> <manvolnum > 8</manvolnum> </citerefentry> ,
<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.device</refentrytitle> <manvolnum > 5</manvolnum> </citerefentry> ,
<citerefentry > <refentrytitle > systemd.mount</refentrytitle> <manvolnum > 5</manvolnum> </citerefentry> ,
<citerefentry > <refentrytitle > swapon</refentrytitle> <manvolnum > 8</manvolnum> </citerefentry>
</para>
</refsect1>
</refentry>
