How to enable swap in ubuntu and debian?

What is swap space?

Swap space in any operating system is amount of disk space reserve for moving inactive pages from RAM. Swap space are of two type dedicate swap or of swap files in linux OS. Here we will create a swap file for the linux system.

We assume that the system does have not swap partition for this guide.

Check if your system already exist swap partition.

Open the terminal, and enter the following command to check.

swapon --show

Check free memory and disk.

free h
 //or
 df -h

If you have sufficient space in you hard-disk then lets continue.

Step:1 Make swap off

swapoff /var/swapfile

Step 2: Resize the swapfile

Here let us increase to 2GB (assuming existing one has 1GB space as given in the article)

dd if=/dev/zero of=/var/swapfile bs=1024k count=2000

Step 3: Make swapfile usable

mkswap /var/swapfile

Step 4: Make swapon

swapon /var/swapfile

Step 5: Change permission to 0600

chmod 0600 /var/swapfile

Step 6: Verify the swapfile

swapon -show

Step 7: Make swap file permanent

echo '/var/swapfile none swap sw 0 0' | tee -a /etc/fstab