Mkswap

mkswap is the command used to format a file or partition for use as swap space.

Usage
Format an existing file or partition for use as swap space mkswap [-v]  Enable a swap area swapon [-v] 

Disable a swap area swapoff [-v] 

Enable all swap areas mentioned in /etc/fstab swapon -a [-v]

Show active swap areas swapon -s [-v]

where the target is a swap file or partition

Provided by
Most (all?) Linux distributions incorporate this from the [util-linux] package