How to create swap memory in Linux?

To create swap space on Linux, you can follow these steps:

1. Check the available disk space: Open a terminal and run the command `df -h` or `sudo swapon --show` or `free -h` to view the current disk space usage. Ensure that you have enough free space for the swap file.
2. Create a swap file: Use the `fallocate` command to create a swap file of the desired size. For example, to create a 2GB swap file, run the following command:

   sudo fallocate -l 2G /swapfile

3. Set appropriate permissions: Change the permissions of the swap file to restrict access only to the root user:

   sudo chmod 600 /swapfile

4. Configure the swap file: Enable the swap file by turning it into a swap area using the `mkswap` command:

   sudo mkswap /swapfile

5. Activate the swap file: Activate the swap file using the `swapon` command:

   sudo swapon /swapfile

6. Make the swap file persistent: To ensure that the swap file is automatically enabled on system boot, open the `/etc/fstab` file in a text editor (e.g., `sudo nano /etc/fstab`) and add the following line at the end of the file:

   /swapfile none swap sw 0 0

   You can also run the following command to add this line to the fstab file:

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

   Don't forget to take a backup of your fstab file:

   sudo cp /etc/fstab /etc/fstab.bak

7. Verify the swap space: Run the `free -h` command to verify that the swap space is active and available. It should look something like this.
   

That's it! You have successfully created swap space on Linux using a swap file. The system will now use this swap space as additional virtual memory when required.