remove linux kernel

How to: Linux delete or remove kernel

by Vivek Gite




Q. I have multiple
versions installed and I need to save disk space. I am using Cent OS
Linux. How can I delete or remove a Linux kernel from my Linux
distribution ?

A. Linux Kernel and related files are stored in following locations:

=> /boot - Stores actual kernel and related file such system man and initrd images,

=> /etc or /boot/grub - Stores grub.conf file (most distro use /boot/grub these days).

=> /iib/modules/KERNEL-VERSION/* - Linux device drivers (modules)

If kernel is installed using binary package system such as rpm, yum,
up2date, apt-get etc you can remove with following commands:

Rpm based distro - Red Hat/CentOS/Fedora Core/Suse Linux

First find out all installed kernel version with following command:

# rpm -qa | grep kernel-smp

or

# rpm -qa | grep kernel

Output:

kernel-smp-2.6.9-42.EL
kernel-smp-2.6.9-42.0.3.EL
kernel-smp-2.6.9-42.0.8.EL

I've total 3 different kernel installed. To remove kernel-smp-2.6.9-42.EL type command:

# rpm -e kernel-smp-2.6.9-42.EL

OR

# rpm -vv -e kernel-smp-2.6.9-42.EL

.deb based distro - Debian or Ubuntu Linux

Again find out all installed kernel version:

$ dpkg --list | grep kernel-image

Output:

ii  kernel-image-2.4.27-2-386   2.4.27-10sarge1             Linux kernel image for version 2.4.27 on 386
ii  kernel-image-2.6.8-2-686    2.6.8-16sarge1              Linux kernel image for version 2.6.8 on PPro

Now remove kernel-image-2.4.27-2-386 with apt-get command itself:

# apt-get remove kernel-image-2.4.27-2-386

OR

$ sudo apt-get remove kernel-image-2.4.27-2-386

If you have custom compiled kernel you need to remove following files/dirs:

/boot/vmlinuz*KERNEL-VERSION*

/boot/initrd*KERNEL-VERSION*

/boot/System-map*KERNEL-VERSION*

/boot/config-*KERNEL-VERSION*

/lib/modules/*KERNEL-VERSION*/

Update grub configuration file /etc/grub.conf or /boot/grub/menu.lst to point to correct kernel version.