my ac66u configuration is kind of 'modular', and i happen to have a 'swap management' module.
im posting it here so maybe you can adapt it to your needs.
it first looks for a swap partition and mount it if found.
if not, it looks for a swap image file and mount it if found.
if not, creates the file and mount it.
ramon@ac66u:/tmp/home/root# cat /mnt/EXT3_29G/config/criar-swap.sh
Code:
#!/bin/sh
# ------------------------------------------------------------------------------
# SOURCING AUX FUNCTIONS
# ------------------------------------------------------------------------------
if ! source /mnt/EXT3_29G/config/aux-functions.sh ; then
SCRIPTNAME=$(basename $0)
echo "$SCRIPTNAME: Error sourcing /mnt/EXT3_29G/config/aux-functions.sh"
logger -t "$SCRIPTNAME" "Error sourcing /mnt/EXT3_29G/config/aux-functions.sh"
exit 1
fi
# ------------------------------------------------------------------------------
# CONFIG
# ------------------------------------------------------------------------------
SWAPSIZE=256
WORKDIR=/mnt/EXT3_29G/config
cd $WORKDIR
# ------------------------------------------------------------------------------
# START
# ------------------------------------------------------------------------------
echoAndLog "Starting script $0"
SWAPDEV=$(fdisk -l | awk '/swap/{print $1}')
SWAPLABEL=$(blkid $SWAPDEV | grep -oP '(?<=LABEL=")\w+(?="\s)')
SWAPUUID=$(blkid $SWAPDEV | grep -oP '(?<=UUID=").*(?="$)')
if [ "$SWAPDEV" ] ; then
echoAndLog "Found swap partition $SWAPDEV LABEL=$SWAPLABEL UUID=$SWAPUUID"
echoAndLog "Enabling swap partition"
swapoff $SWAPDEV 2>/dev/null
swapon $SWAPDEV || echoAndLog "Error enabling swap partition"
else
echoAndLog "No swap partition found. Will try with file"
if [ -s swapfile.img ] && [ "$(du -m swapfile.img | awk '{print $1}')" -eq 256 ] ; then
echoAndLog "Found a ${SWAPSIZE}M image file"
else
echoAndLog "Creating ${SWAPSIZE}M image file"
dd if=/dev/zero of=swapfile.img bs=1024 count=${SWAPSIZE}K || echoAndLog "Error creating image file"
fi
echoAndLog "Setting image file as swap"
mkswap swapfile.img || echoAndLog "Error setting image file as swap"
echoAndLog "Setting swap file permissions"
chmod 0600 swapfile.img || echoAndLog "Error setting swap file permissions"
echoAndLog "Enabling swap file"
swapoff swapfile.img 2>/dev/null
swapon swapfile.img || echoAndLog "Error enabling swap file"
fi
echoAndLog "$(free | awk '/Swap/{ print $1, "total", $2, "used", $3, "free", $4 }')"
echoAndLog "Script finished"
