Removes all kernels installed under Debian/Ubuntu that aren't loaded.

remove-old-kernels.sh

#!/bin/bash

kernels=$(dpkg -l | grep -E "ii  linux-(image|headers)-[0-9]\.[0-9]\.[0-9]-.*" | grep -v $(uname -r | cut -d"-" -f1,2) | cut -d" " -f3)
echo "Current kernel: $(uname -r)"
echo "Remove kernels:"
echo "$kernels"
read -p "Execute? (y/n)" choice
if [ "$choice" == "y" ]
then
  echo $kernels | xargs sudo apt-get remove -y
else
  echo "Abort."
fi