Clean ubuntu

This page explains how to remove old and un-necessary kernels as well as cleaning the /boot partition.

Know the current Kernel version

Get your current kernel version

uname -r

You should see something like:

3.13.0-32-generic

Installed kernels

List kernels that can be removed

The following command will return the list of packages that can be removed:

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

Source: Linux pratique no94, FR, mars|avril 2016

List of all kernels (including current one)

Get a list of installed kernels

dpkg --list 'linux-image*'

You should see something like:

/	Name	Version	Architecture	Description
un	linux-image	<none>	<none>	(no description available)
un	linux-image-3.0	<none>	<none>	(no description available)
rc	linux-image-3.13.0-24-generic	3.13.0-24.47	amd64	Linux kernel image for version 3.13.0 on 64 bit x86 SMP
ii	linux-image-3.13.0-30-generic	3.13.0-30.55	amd64	Linux kernel image for version 3.13.0 on 64 bit x86 SMP
ii	linux-image-3.13.0-32-generic	3.13.0-32.57	amd64	Linux kernel image for version 3.13.0 on 64 bit x86 SMP
rc	linux-image-extra-3.13.0-24-generic	3.13.0-24.47	amd64	Linux kernel extra modules for version 3.13.0 on 64 bit x86 SMP
ii	linux-image-extra-3.13.0-30-generic	3.13.0-30.55	amd64	Linux kernel extra modules for version 3.13.0 on 64 bit x86 SMP
ii	linux-image-extra-3.13.0-32-generic	3.13.0-32.57	amd64	Linux kernel extra modules for version 3.13.0 on 64 bit x86 SMP
ii	linux-image-generic	3.13.0.32.38	amd64	Generic Linux kernel image

Delete kernels

Automatic deletion

# list the package to remove
dpkg -l | awk '{print $2}' | grep -E "linux-(image|headers)-$(uname -r | cut -d- -f1).*" | grep -v $(uname -r | sed -r -e 's:-[a-z]+.*::')

# remove all old kernels at once
apt-get purge $(dpkg -l | awk '{print $2}' | grep -E "linux-(image|headers)-$(uname -r | cut -d- -f1).*" | grep -v $(uname -r | sed -r -e 's:-[a-z]+.*::'))

# update grub
update-grub

Source: Linux pratique no94, FR, mars|avril 2016

Manual deletion

Delete the kernels you don't want/need anymore

# Remove old kernels (repeat for each version)
OLD_KRNL_VERSION=4.4.0-21
apt-get remove --purge linux-headers-${OLD_KRNL_VERSION}* linux-image-${OLD_KRNL_VERSION}* linux-image-extra-${OLD_KRNL_VERSION}*

# at the end update Grub
update-grub

set OLD_KRNL_VERSION to the version of the kernel you want to remove.