Cleanup old kernels in Debian based systems (Ubuntu, Pop!_OS, Linux Mint).

cleanup_old_kernels.sh

#!/bin/bash
set -e

current=$(uname -r)
echo "Current kernel: $current"

kernels=$(dpkg --list | grep linux-image-[0-9] | awk '{print $2}')
to_remove=$(echo "$kernels" | grep -v "$current")

if [ -z "$to_remove" ]; then
    echo "No old kernels found."
    exit 0
fi

echo "Removing:"
echo "$to_remove"

sudo apt remove --purge -y $to_remove
sudo apt autoremove --purge -y
sudo update-grub

echo "Cleanup done. Only the current kernel is kept."