# ls -l
total 7365829
-rw-------   1 root     root     4294967296 Jul 26 15:58 swap.1
# swap --help
swap: illegal option -- help
Usage:  swap -l
        sub option :
                -h : displays size in human readable format
                -k : displays size in KB
        swap -s
        sub option :
                -h : displays size in human readable format rather than KB
        swap -d <file name> [low block]
        swap -a <file name> [low block] [nbr of blocks]
# swap -a swap.1
swap: path must be absolute
# swap -a /swap_volume/swap.1
"/swap_volume/swap.1" is not valid for swapping.
It must be a block device or a regular file with the
"save user text on execution" bit set.
# ls -l /swap_volume/swap.1
-rw-------   1 root     root     4294967296 Jul 26 15:58 /swap_volume/swap.1
# ls -lh /swap_volume/swap.1
-rw-------   1 root     root        4.0G Jul 26 15:58 /swap_volume/swap.1
# file /swap_volume/swap.1
/swap_volume/swap.1:    English text
# chmod +t /swap_volume/swap.1
# swap -a /swap_volume/swap.1
"/swap_volume/swap.1" may contain holes - can't swap on it.
# pwd
/swap_volume
# mkfile 4g swap.2
# ls -l
total 15755514
-rw------T   1 root     root     4294967296 Jul 26 15:58 swap.1
-rw------T   1 root     root     4294967296 Jul 27 11:49 swap.2
# swap -a /swap_volume/swap.2
/swap_volume/swap.2: Invalid operation for this filesystem type