Create SWAP at Linux

SWAP_FILE=/swapfile
BLOCK_SIZE=1024
SWAP_SIZE=1000 # 1000M
SWAP_BLOCKS=$BLOCK_SIZE*$SWAP_SIZE
 
# Create file
dd if=/dev/zero of=$SWAP_FILE bs=$BLOCK_SIZE count=$SWAP_BLOCKS
 
 
mkswap $SWAP_FILE
chown root:root $SWAP_FILE
chmod 0600 $SWAP_FILE
swapon $SWAP_FILE
 
echo "$SWAP_FILE swap swap defaults 0 0" >> /etc/fstab
 
free -m