Clean up useless kernels on partition /boot

cleanup_old_kernels.md

do-release-upgrade fail?

May be you got a warinning message when you execute do-release-upgrade:

Not enough free disk space

The upgrade has aborted. The upgrade needs a total of xxx M free space on disk '/boot'. Please free at least an additional xxx M of disk space on '/boot'. Empty your trash and remove temporary packages of former installations using 'sudo apt-get clean'.

Because your /boot partition is filled with old kernels. You can easily remove the old kernels if you know which packages they came in.

First check your current version:

uname -a

Then run the following command:

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d'

This command will list all packages that you no longer need. I don't like removing them automatically, I like to be in control when it comes to removing kernels. So for every package listed do the following:

sudo apt-get -y purge some-kernel-package

Where some-kernel-package can be replaced with one of the packages listed. Just beware that you don't remove the kernel packages that are in current use (as listed by the uname -a) eg. sudo apt-get purge -y linux-headers-3.8.0-39 etc.

It can be automated further using the xargs command, here's the command to do so:

dpkg -l 'linux-*' | sed '/^ii/!d;/'"$(uname -r | sed "s/\(.*\)-\([^0-9]\+\)/\1/")"'/d;s/^[^ ]* [^ ]* \([^ ]*\).*/\1/;/[0-9]/!d' | xargs sudo apt-get -y purge

It's done!