purge ubuntu old kernels

purge_ubuntu.bash

#!/bin/bash

sudo apt-get update
sudo apt-get autoclean
sudo apt-get clean
sudo apt-get autoremove

kernel_pkgs=$( dpkg -l | grep -E 'linux-image-[0-9]' | awk '{ print $2 }' )
current_kernel=$( uname -r )

for pkg in $kernel_pkgs ; do

    version=$( echo $pkg | sed -e "s/linux-image-//" )
    pkg_extra=$( echo $pkg | sed -e "s/linux-image-/linux-image-extra-/" )

    if [ ! $version == $current_kernel ] ; then
       echo delete kernel $pkg
       sudo dpkg --purge $pkg
       sudo dpkg --purge $pkg_extra
       sudo rm -Rf /usr/src/linux-headers-$version
       sudo rm -Rf /usr/src/linux-headers-${version}-generic
    else
       echo keeping current kernel $pkg
    fi

done