swap – establish a swap file|
Swap establishes a file or device for the system to swap on. If
file is a device, the device is used directly; if a directory,
a unique file is created in that directory on which to swap. The
environment variable swap is set to the full name of the resulting
file. The number of blocks available in the file or device must
least the number of swap blocks configured at system boot time.
If a swap channel has already been set and no blocks are currently
valid in the file the old file will be closed and then replaced.
If any blocks are valid on the device an error is returned instead.
Swapping to a file served by a local user–level process, such as
kfs(4), can lead to deadlock; use raw devices or remote files