centos 6 - create swap file

create swap file on centos 6 :
1/ cd /var
2/ touch swap.img
3/ chmod 600 swap.img
4/ dd if=/dev/zero of=/var/swap.img bs=512 count=1000k
5/ mkswap /var/swap.img
6/ swapon /var/swap.img
7/ echo "/var/swap.img none swap sw 0 0" /etc/fstab