Not every Linux server I maintain needs to have a swap partition and to start swapping. For instance, the MySQL servers all have more than enough RAM on board to do their work. Yet, when a swap partition is enabled Linux starts swapping, which may degrade MySQL database performance…

Bash script to turn off Linux swap

An unwanted Linux swap partition can be the result of an automated and unattended Linux installation. Of course you can fiddle with the Linux kernel swapiness settings, located in /proc/sys/vm/swapiness and configurable in /etc/sysctl.conf, but one can turn off the swap completely too.

Here’s a tiny bash script to disable Linux’ swap – for which we use the swapoff command – and to comment out the swap partition in /etc/fstab

#!/bin/bash
# swapoff -a to disable swapping
swapoff -a
# sed to comment the swap partition in /etc/fstab
sed -i.bak -r 's/(.+ swap .+)/#\1/' /etc/fstab

Save this as turn_swap_off.sh and execute as root:

sh /root/turn_swap_off.sh

A backup of the /etc/fstab file is made just to be sure and to stay on the safe side.