1. Determine the size of the new swap file and multiple by 1024 to determine the block size. For example,
the block size of a 64 MB swap file is 65536.
2. At a shell prompt as root, type the following command with count being equal to the desired block size:
dd if=/dev/zero of=/swapfile bs=1024 count=65536
3. Setup the swap file with the command:
mkswap /swapfile
4. To enable the swap file immediately but not automatically at boot time:
swapon /swapfile
5. To enable it at boot time, edit /etc/fstab to include:
/swapfile swap swap defaults 0 0