The device or file used is given by the specialfile parameter. It may be of the form -L label or -U uuid to indicate a device by label or uuid.
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:
|-a||All devices marked as swap swap devices in /etc/fstab are made available, except for those with the noauto option. 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.|
|Use the partition that has the specified label. (For this, access to /proc/partitions is needed.)|
|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. Higher numbers indicate higher priority. 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.|
|-s||Display swap usage summary by device. Equivalent to "cat /proc/swaps". Not available before Linux 2.1.25.|
|-U uuid||Use the partition that has the specified uuid. (For this, access to /proc/partitions is needed.)|