How to add a swap file on a VPS

Creating the swap file

To begin with, before creating a swap file, it is advisable to check the list of mounted partitions and their size. To do this, execute the df -h command.

In this example, a swap file will be created in the /var directory with a size of 4GB.

1. Creating a swap file

   sudo touch /var/.swap.img
   sudo chmod 600 /var/.swap.img

2. We fill the file with zeros to the desired size. In this example, the swap size will be 4GB

   sudo dd if=/dev/zero of=/var/.swap.img bs=1024k count=4096​

3. Format the swap file as swap space

   sudo mkswap /var/.swap.img​

4. Activate the swap file

   sudo swapon /var/.swap.img​

5. To make the swap file persistent across reboots, add it to the /etc/fstab file

   sudo echo "/var/.swap.img none swap sw 0 0" >> /etc/fstab​

6. Verify that the swap file is active and working correctly by using the free command or the swapon command:

   free -h​

   or

   swapon --show​

The swap file will now provide additional virtual memory to your system, which can be beneficial for managing memory-intensive tasks.