purge unused kernels in ubuntu to avoid boot partition form filling up

purge-unused-kernels.sh

#! /bin/sh
dpkg --get-selections | grep 'linux-image-*' | awk '{print $1}' | egrep -v "linux-image-$(uname -r)|linux-image-generic" |  head -n -2 | sed 's/^linux-image-\(.*\)$/\1/' | \
while read n; do
  echo 'Purging unneeded kernel images and headers for: '$n
  sudo apt-get --yes purge linux-image-$n    #purge images
  sudo apt-get --yes purge linux-headers-$n  #purge headers
done