How to uninstall the old kernels in Ubuntu (and grub)

How can we remove the unused linux kernels and at the same time have our boot configuration (grub’s entries in the grub cfg menu) updated?

First we want to list all the kernel-related packages, like linux-image and linux-headers, linux-generic, etc:

$ dpkg -l linux-*

On my 10.04 Ubuntu system the above command results in the following list of packages:

These are all the “linux-” packages that dpkg knows of at the moment (installed and not installed). Let’s say we want to remove all the kernels except the most recent one. Actually, leaving one of the older ones, just in case, is usually a good idea 😉

We’ll use awk and grep to filter the above list, getting just the 2nd column (which contains the actual names of packages) for those rows which contain the unwanted packages. The easiest thing to do (especially if you’re not a grep/gawk guru) is to use the unwanted kernel versions as a grep search string at the same time telling awk to print just the 2nd column, e.g. this will print all the packages of the 2.6.32-30 kernel:

$ dpkg -l linux-* | awk '{ print $2 }' | grep -w 30

linux-headers-2.6.32-30
linux-headers-2.6.32-30-generic
linux-image-2.6.32-30-generic

We can now give all of these files to apt-get (via xargs) for removal:

$ dpkg -l linux-* | awk '/^ii/{ print $2 }' | grep -w 30 | xargs sudo apt-get -y purge

… do the same for all the other kernel packages that you no longer want on your system.