swapon, swapoff – enable/disable devices and files for paging and swapping 

/dev/hda5 – activate the swap

/sbin/swapon [-h -V]
/sbin/swapon -a [-v] [-e]
/sbin/swapon [-v] [-p priorityspecialfile 
/sbin/swapon [-s]
/sbin/swapoff [-h -V]
/sbin/swapoff -a
/sbin/swapoff specialfile  


Swapon is used to specify devices on which paging and swapping are to take place. Calls toswapon normally occur in the system multi-user initialization file /etc/rc making all swap devices available, so that the paging and swapping activity is interleaved across several devices and files.

Normally, the first form is used:

Provide help
Display version
Display swap usage summary by device. Equivalent to “cat /proc/swaps”. Not available before Linux 2.1.25.
All devices marked as “swap” swap devices in /etc/fstab are made available. Devices that are already running as swap are silently skipped.
When -a is used with swapon, -e makes swapon silently skip devices that do not exist.
-p priority
Specify priority for swapon. This option is only available if swapon was compiled under and is used under a 1.3.2 or later kernel. priority is a value between 0 and 32767. See swapon for a full description of swap priorities. Add pri=value to the option field of/etc/fstab for use with swapon -a.