bc-kernel-cleanup

#!/usr/bin/env bash
#
# Deletes all kernels except the currently booted one, and the newest. (Possibly not ideal if you want different types, like the lowlatency, and xen and generic all at the same time)
# Author: Peter Maloney

args=()
if [ "$1" = "-n" -o "$1" = "--dry-run" -o "$1" = "-s" -o "$1" = "--simulate" ]; then
    # dry run
    args=(--dry-run)
else
    args=(-y)
fi

# takes one arg with space separated numbers, eg. version 4.3-1 is sent here as "4 3" and a second call takes "1"
# left-0-pads each number into 10 digits, eg. 00000000040000000003 so length of the numbers doesn't matter for sorting, and then right-zero-pads that to 50 length so having more numbers doesn't make the version larger (until you exceed 5 numbers or 50 chars)
pad() {
    IFS=' '
    local lpad=
    for n in $1; do
        lpad="${lpad}$(printf "%010d" "$n")"
    done

    local rpad="$lpad"

    while [ "${#rpad}" -lt 50 ]; do
        rpad="${rpad}0"
    done
    echo -n "$rpad"
}

# sorts by version, trying to handle all the dotted and hyphenated numbers
version_sort() {
    IFS=$'\n'
    for line in $(cat); do
        local base_split=$(awk -F'-' '{print $1}' <<< "$line" | sed -r 's|[^0-9a-zA-Z]| |g')
        local distro_split=$(awk -F'-' '{print $2}' <<< "$line" | sed -r 's|[^0-9a-zA-Z]| |g')

        local base_padded=$(pad "$base_split")
        local distro_padded=$(pad "$distro_split")

        echo "$line $base_padded $distro_padded"
    done | sort -t' ' -k2,2n -k3,3n | cut -d' ' -f1
}

current=$(uname -r | grep -Eo "[0-9][0-9\.-]+[0-9]")

autoremove() {
    name="$1"

    latest=$(dpkg -l "${name}*" | awk '$1=="ii" {print $2}' | grep -Eo "[0-9][0-9\.-]+[0-9]" | version_sort | tail -n1)

    # remove all except the currently booted one, and the latest one
    apt-get purge "${args[@]}" $(dpkg -l "${name}*" | grep -E "${name}-[0-9\.-]+" | awk '$1 == "ii" || $1 == "rc" {print $2}' | grep -vE "$current|$latest")
}

# debian/ubuntu kernels
autoremove "linux-image"
autoremove "linux-headers"
autoremove "linux-image-extra"
# proxmox PVE kernels
autoremove "pve-kernel"
autoremove "pve-headers"