Create and Add a new Swap File to your Ubuntu or Debian Server VPS

Start by creating a file which will be used for swap:

sudo fallocate -l 1G /swapfile

If fallocate is not installed or you get an error message saying fallocate failed:
Operation not supported then use the following command to create the swap file:

sudo dd if=/dev/zero of=/swapfile bs=1024 count=1048576

Only the root user should be able to write and read the swap file. Set the correct permissions by typing:

sudo chmod 600 /swapfile

Use the mkswap utility to set up a Linux swap area on the file:

sudo mkswap /swapfile

Activate the swap file:

sudo swapon /swapfile

To make the change permanent open the /etc/fstab file:

sudo nano /etc/fstab

and paste the following line into /etc/fstab:

/swapfile swap swap defaults 0 0

Verify that the swap is active by using either the swapon or the free command , as shown below:

sudo swapon --show
/swapfile file 1024M 507.4M -1
sudo free -h
total used free shared buff/cache available
Mem: 488M 158M 83M 2.3M 246M 217M
Swap: 1.0G 506M 517M