Create swap file for your VPS

Just got a VPS for your own use? RAM only 512MB? or maybe you are accustomed to out of memory error and need a way to increase your memory.
Then you got to have a swap file for your VPS, the size of which will depend on your usage.

One thing to remember, swap file is created on your storage. So don't expect it to be as fast as your RAM.

Here are the steps you can follow (works on Ubuntu 12.04):
1. Check for existing swap file, if you already have one then all are good.
    swapon -s

2. Create your file for the swap file
sudo dd if=/dev/zero of=/swapfile bs=1024 count=256k

3. Set it as swap file
sudo mkswap /swapfile

4. Register the swap file
sudo swapon /swapfile

5. Make it permanent on the system
sudo nano /etc/fstab

And add the following line at the end:
/swapfile       none    swap    sw      0       0 

6. Set the swappiness
echo 10 | sudo tee /proc/sys/vm/swappiness
echo vm.swappiness = 10 | sudo tee -a /etc/sysctl.conf

7. Protect the file

sudo chown root:root /swapfile 

sudo chmod 0600 /swapfile

That's all, enjoy your VPS.

Reference:

https://www.digitalocean.com/community/tutorials/how-to-add-swap-on-ubuntu-12-04