SWAPON

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

/sbin/swapon [−h −V]
/sbin/swapon −a [−v] [−e]
/sbin/swapon [−v] [−p priority] specialfile ...
/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 to swapon 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:

−h

Provide help

−V

Display version

−s

Display swap usage summary by device. This option is only available if /proc/swaps exists (probably not before kernel 2.1.25).

−a

All devices marked as ‘‘sw’’ swap devices in /etc/fstab are made available. Devices that are already running as swap are silently skipped.

−e

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(2) for a full description of swap priorities. Add pri=value to the option field of /etc/fstab for use with swapon -a.

Swapoff disables swapping on the specified devices and files, or on all swap entries in /etc/fstab when the −a flag is given.

You should not use swapon on a file with holes. Swap over NFS may not work.

swapon(2), swapoff(2), fstab(5), init(8), mkswap(8), rc(8), mount(8)

/dev/hd?? standard paging devices
/dev/sd?? standard (SCSI) paging devices
/etc/fstab ascii filesystem description table

The swapon command appeared in 4.0BSD.