Physical memory full issue: Create Linux swap file after installing the linux operating system step by step guide

In this article we learn how to create linux swap file after installing linux operating system , how to activate swap file after installing the swap file and how to remove swap file from linux operating system.

What is SWAP in linux

SWAP file is a space on disk which is taking over the control that means all inactive pages are moved from the physical memory of the system to the SWAP space when all physical memory is consumed or full.

How to create and activate SWAP file on disk of linux system

To create SWAP file on disk of a linux system we need to execute the below command.

We want to create SWAP file named (swapfile) with size 2GB on / partition.To do this we execute the below command.

[root@techrideradmin ~]# dd if=/dev/zero of=/swapfile bs=1M count=2048

2048+0 records in

2048+0 records out

2147483648 bytes (2.1 GB) copied, 25.9823 s, 82.7 MB/s

Create Linux swap file after installing the linux operating system step by step guide

After creating this we need to format it into SWAP. To do this we execute the below command.

[root@techrideradmin ~]# mkswap /swapfile

Setting up swapspace version 1, size = 2097148 KiB

no label, UUID=3653e4ed-30fb-4c7d-971f-4fd3bc22396e

Now we need to change the permission of the SWAP file .Only root user can read and write the file. To do this we need to execute the below command.

[root@techrideradmin ~]# chmod 600 /swapfile

To activate the SWAP file and verify the SWAP file we need to execute the below commands.

[root@techrideradmin ~]# swapon -a

[root@techrideradmin ~]# swapon -s

To make change permanently we append the following line into the “/etc/fstab”.

/swapfile swap swap defaults 0 0

After doing all the above steps we finally verify the SWAP file to execute the below command.

[root@techrideradmin ~]# free –g

How to remove SWAP file from the linux system.

To remove the SWAP file from the linux system first we need to deactivate the SWAP file using the below command.

[root@techrideradmin ~]# swapoff -a

After that we remove the SWAP file entry from the “/etc/fstab”.

And finally we remove the /swapfile using the below command.

[root@techrideradmin ~]# rm /swapfile

rm: remove regular file `/swapfile'? y

Physical memory full issue: Create Linux swap file after installing the linux operating system step by step guide