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.TH "SYSTEMD\&.SWAP" "5" "" "systemd 230" "systemd.swap"
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.SH "NAME"
systemd.swap \- Swap unit configuration
.SH "SYNOPSIS"
.PP
\fIswap\fR\&.swap
.SH "DESCRIPTION"
.PP
A unit configuration file whose name ends in
"\&.swap"
encodes information about a swap device or file for memory paging controlled and supervised by systemd\&.
.PP
This man page lists the configuration options specific to this unit type\&. See
\fBsystemd.unit\fR(5)
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\&.
.PP
Additional options are listed in
\fBsystemd.exec\fR(5), which define the execution environment the
\fBswapon\fR(8)
binary is executed in, in
\fBsystemd.kill\fR(5), which define the way these processes are terminated, and in
\fBsystemd.resource-control\fR(5), which configure resource control settings for these processes of the unit\&.
.PP
Swap units must be named after the devices or files they control\&. Example: the swap device
/dev/sda5
must be configured in a unit file
dev\-sda5\&.swap\&. For details about the escaping logic used to convert a file system path to a unit name, see
\fBsystemd.unit\fR(5)\&. Note that swap units cannot be templated, nor is possible to add multiple names to a swap unit by creating additional symlinks to it\&.
.SH "AUTOMATIC DEPENDENCIES"
.PP
All swap units automatically get the
\fIBindsTo=\fR
and
\fIAfter=\fR
dependencies on the device units or the mount units of the files they are activated from\&.
.PP
Swap units with
\fIDefaultDependencies=\fR
in the
"[Unit]"
section enabled implicitly acquire a
\fIConflicts=\fR
and an
\fIAfter=\fR
dependency on
umount\&.target
so that they are deactivated at shutdown, unless
\fIDefaultDependencies=no\fR
is specified\&.
.PP
Additional implicit dependencies may be added as result of execution and resource control parameters as documented in
\fBsystemd.exec\fR(5)
and
\fBsystemd.resource-control\fR(5)\&.
.SH "FSTAB"
.PP
Swap units may either be configured via unit files, or via
/etc/fstab
(see
\fBfstab\fR(5)
for details)\&. Swaps listed in
/etc/fstab
will be converted into native units dynamically at boot and when the configuration of the system manager is reloaded\&. See
\fBsystemd-fstab-generator\fR(8)
for details about the conversion\&.
.PP
If a swap device or file is configured in both
/etc/fstab
and a unit file, the configuration in the latter takes precedence\&.
.PP
When reading
/etc/fstab, a few special options are understood by systemd which influence how dependencies are created for swap units\&.
.PP
\fBnoauto\fR, \fBauto\fR
.RS 4
With
\fBnoauto\fR, the swap unit will not be added as a dependency for
swap\&.target\&. This means that it will not be activated automatically during boot, unless it is pulled in by some other unit\&. The
\fBauto\fR
option has the opposite meaning and is the default\&.
.RE
.PP
\fBnofail\fR
.RS 4
With
\fBnofail\fR, the swap unit will be only wanted, not required by
swap\&.target\&. This means that the boot will continue even if this swap device is not activated successfully\&.
.RE
.SH "OPTIONS"
.PP
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
\fBsystemd.exec\fR(5)
and
\fBsystemd.kill\fR(5)\&. The options specific to the [Swap] section of swap units are the following:
.PP
\fIWhat=\fR
.RS 4
Takes an absolute path of a device node or file to use for paging\&. See
\fBswapon\fR(8)
for details\&. If this refers to a device node, a dependency on the respective device unit is automatically created\&. (See
\fBsystemd.device\fR(5)
for more information\&.) If this refers to a file, a dependency on the respective mount unit is automatically created\&. (See
\fBsystemd.mount\fR(5)
for more information\&.) This option is mandatory\&.
.RE
.PP
\fIPriority=\fR
.RS 4
Swap priority to use when activating the swap device or file\&. This takes an integer\&. This setting is optional\&.
.RE
.PP
\fIOptions=\fR
.RS 4
May contain an option string for the swap device\&. This may be used for controlling discard options among other functionality, if the swap backing device supports the discard or trim operation\&. (See
\fBswapon\fR(8)
for more information\&.)
.RE
.PP
\fITimeoutSec=\fR
.RS 4
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
\fBSIGTERM\fR, and after another delay of this time with
\fBSIGKILL\fR\&. (See
\fBKillMode=\fR
in
\fBsystemd.kill\fR(5)\&.) 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
\fIDefaultTimeoutStartSec=\fR
from the manager configuration file (see
\fBsystemd-system.conf\fR(5))\&.
.RE
.PP
Check
\fBsystemd.exec\fR(5)
and
\fBsystemd.kill\fR(5)
for more settings\&.
.SH "SEE ALSO"
.PP
\fBsystemd\fR(1),
\fBsystemctl\fR(1),
\fBsystemd.unit\fR(5),
\fBsystemd.exec\fR(5),
\fBsystemd.kill\fR(5),
\fBsystemd.resource-control\fR(5),
\fBsystemd.device\fR(5),
\fBsystemd.mount\fR(5),
\fBswapon\fR(8),
\fBsystemd-fstab-generator\fR(8),
\fBsystemd.directives\fR(7)