#!/bin/bash
read -a kernels_installed <<< `dpkg -l 'linux-image-[0-9]*' | grep ^ii | awk '{ print $2 }'`
kernel_links=(/vmlinuz /vmlinuz.old)
kernels_to_keep=( )
DEBUG=0

for i in ${kernel_links[@]}; do
  if [ $DEBUG -eq 1 ]; then echo "Checking $i"; fi
  real_kernel_link=`readlink $i`
  if [ $DEBUG -eq 1 ]; then echo "$i points to /$real_kernel_link"; fi
  if [ $? -ne 0 ]; then
    # we didn't find a kernel - bail - we want both
    exit 1
  fi
  # Get the package this came from
  dpkg_search=`dpkg -S /$real_kernel_link`
  if [ $DEBUG -eq 1 ]; then echo "$real_kernel_link found: $dpkg_search"; fi
  if [ $? -ne 0 ]; then
    # Couldn't find a package? Bail
    exit 1
  fi
  # We want just the package name
  dpkg_name=`echo "$dpkg_search" | cut -d: -f 1`
  # and we add it to the list
  kernels_to_keep+=($dpkg_name)
done

# Bonus feature - won't delete current kernel
current_kernel_version=`uname -r`
kernels_to_keep+=("linux-image-$current_kernel_version")

if [ $DEBUG -eq 1 ]; then echo "Keeping: ${kernels_to_keep[@]}"; fi

kernels_to_delete=(${kernels_installed[@]})

# Remove the kernels we want to keep from the list
for i in ${kernels_to_keep[@]}; do
  kernels_to_delete=(${kernels_to_delete[@]##$i})
done

if [ $DEBUG -eq 1 ]; then echo "Found: ${kernels_installed[@]}"; fi
if [ $DEBUG -eq 1 ]; then echo "Deleting: ${kernels_to_delete[@]}"; fi

if [ $DEBUG -eq 1 ]; then
  dry_run="-s"
else
  dry_run=""
fi


# Here goes... good luck. 
apt-get -y $dry_run remove ${kernels_to_delete[@]}