#!/bin/bash
# this is a script for purging unused old kernels installed in your system,
# you should use this script under newest kernel installed!!!
# Please, run it with sudo or as a root user (needed only for apt-get purge operation)!

# checking for root privileges
if [ "$(id -u)" != "0" ]; then
echo 'This script must be run as root or with sudo command!!!' 2>&1
exit 1
fi

# let's get installed and removed kernels list
# and exclude removed kernels
# and exclude kernel you are using now
# excluding kernel metapackage too (list only linux-image-2....),
# then we are going to write this list to a temporary file
dpkg --get-selections linux-image*\
| grep -v deinstall\
| grep -v `uname -r`\
| grep 2 > /tmp/tmp.txt
# asking user if he wants to purge kernels found...
echo "Old kernels found:"
cat /tmp/tmp.txt
echo "You are now running kernel:"
echo linux-image-`uname -r`
CORRECT_INPUT=0
while [ $CORRECT_INPUT -ne 1 ]
do
	echo -n "Would you like to purge old kernels found? (y/n): "
	read CHOISE
	case $CHOISE in
	y)
	echo "Purging kernels!..."
	CORRECT_INPUT=1
	;;
	n)
	rm /tmp/tmp.txt
	echo "Exiting..."
	CORRECT_INPUT=1
	exit 0
	;;
	*)
	echo "Please enter y or n and press enter!"
	;;
	esac
done
# let's purge unused kernels which are in our tempfile
apt-get -s purge `cat /tmp/tmp.txt | cut --fields=1 -`

echo -n 'Done! Press any key to continue!'
read CONTINUE

# finding old kernel-headers
dpkg --get-selections linux-headers*\
| grep -v deinstall\
| grep 2 > /tmp/tmp.txt
# asking user if he wants to remove old kernel haders too...
echo "Old kernel headers found, script can purge them too:"
cat /tmp/tmp.txt
echo "Your current kernel headers version:"
echo linux-headers-`uname -r`
CORRECT_INPUT2=0
while [ $CORRECT_INPUT2 -ne 1 ]
do
	echo -n "Would you like to purge old kernels headers? (y/n): "
	read CHOISE
	case $CHOISE in
	y)
	echo "Purging kernel headers!..."
	CORRECT_INPUT2=1
	;;
	n)
	rm /tmp/tmp.txt
	echo "Exiting..."
	CORRECT_INPUT2=1
	exit 0
	;;
	*)
	echo "Please enter y or n and press enter!"
	;;
	esac
done
# purging kernel-headers which are in our tempfile
apt-get -s purge `cat /tmp/tmp.txt | cut --fields=1 -`

rm /tmp/tmp.txt
echo 'All done! Exiting script...'
exit 0