Delete old kernel on debian/ubuntu

remove-old-kernels.sh

#!/bin/bash

# 1. Find all the packages that have installed something in /boot
# 2. Trim it down to just the kernel packages (e.g. remove memtest)
# 3. Sort them oldest->newest
# 4. Remove the newest (so we've got the updated kernel to boot into)
# 5. Remove the current kernel (so we can go back to that if the new one fails)
# 6. Pass the package list to apt-get remove for uninstallation
# Note: This code will only simulate removal. Remove -s flag from apt-get to do it for real.

dpkg -S '/boot/*' | cut -d: -f1 | grep linux-image | sort -V | uniq | head -n -1  | grep -v $(uname -a | awk '{print $3}') | xargs sudo apt-get remove -y -s --purge