From 96d691b5ffdfc2104176bc223fd52d83bcc975a1 Mon Sep 17 00:00:00 2001
From: bisco <bisco@younerd.org>
Date: Wed, 3 Jun 2026 18:51:32 +0200
Subject: [PATCH] first release - trivial but working

---
 plonk.sh | 422 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 422 insertions(+)
 create mode 100644 plonk.sh

diff --git a/plonk.sh b/plonk.sh
new file mode 100644
index 0000000..7d5b542
--- /dev/null
+++ b/plonk.sh
@@ -0,0 +1,422 @@
+#!/bin/bash
+# PLONK - PLONK Leaves Only Needed Kernels
+#
+# This script removes old Debian kernels
+# It also purges old kernel packages left in "rc" state
+#
+# In short: old kernels go plonk.
+#
+# Author: bisco <bisco__AT__younerd__DOT_org>
+# Script inspired by the following cyberciti post:
+# https://www.cyberciti.biz/faq/debian-ubuntu-linux-delete-old-kernel-images-command/
+
+set -euo pipefail
+
+### Variables
+
+APT_GET="$(command -v apt-get || true)"
+DPKG_QUERY="$(command -v dpkg-query || true)"
+
+KERNELVER="$(uname -r)"
+KEEP_KERNELS="2"
+
+ACTION=""
+ASSUME_YES="no"
+
+KERNELS_TO_KEEP=()
+ABIS_TO_KEEP=()
+
+OLD_KERNELS=()
+RC_KERNELS=()
+PKGS_TO_PURGE=()
+
+### End Variables
+
+
+### Code.
+### Please don't edit below unless if you know what you're doing.
+
+
+### Check if something went wrong
+check_error(){
+    echo "====> ERROR!"
+    echo "====> Script failed on line ${BASH_LINENO[0]}"
+    exit 1
+}
+
+
+### Run check_error function on errors
+trap check_error ERR
+
+
+### Show help and exits
+usage(){
+    echo "PLONK - PLONK Leaves Only Needed Kernels"
+    echo ""
+    echo "Old kernels go plonk."
+    echo ""
+    echo "Usage: $0 [option]"
+    echo ""
+    echo "-l | --list      : list old kernel packages"
+    echo "-n | --dry-run   : simulate old kernel packages removal"
+    echo "-r | --remove    : remove old kernel packages"
+    echo "-k | --keep NUM  : number of kernels to keep. Default: ${KEEP_KERNELS}"
+    echo "-y | --yes       : assume yes when removing packages"
+    echo "-h | --help      : show this help and exits"
+    echo ""
+    echo "Examples:"
+    echo "$0 --list"
+    echo "$0 --dry-run"
+    echo "sudo $0 --remove"
+    echo "sudo $0 --remove --keep 3"
+    echo ""
+}
+
+
+### Check if all binaries are properly installed on target system
+check_binary(){
+    if [ "${APT_GET}" == "" ] || [ "${DPKG_QUERY}" == "" ]; then
+        echo "[FAIL] Some binaries not found."
+        echo "[INFO] Please make sure you have: apt-get, dpkg-query"
+        exit 1
+    else
+        echo "[OK] All binaries are properly installed. Let's go on!"
+    fi
+}
+
+
+### Check if the script has been run by root when removing packages
+check_root(){
+    if [ "${ACTION}" != "remove" ]; then
+        return
+    fi
+
+    if [ "$(id -u)" == "0" ]; then
+        echo "[OK] Check root permissions"
+    else
+        echo "[FAIL] Check root permissions"
+        echo "[INFO] Run this script as root or sudo"
+        exit 1
+    fi
+}
+
+
+### Extract kernel version from package name
+pkg_to_kernel_version(){
+    local PKG="${1%%:*}"
+
+    case "${PKG}" in
+        linux-image-unsigned-*)
+            echo "${PKG#linux-image-unsigned-}"
+            ;;
+        linux-image-*)
+            echo "${PKG#linux-image-}"
+            ;;
+        linux-headers-*)
+            echo "${PKG#linux-headers-}"
+            ;;
+        *)
+            return 1
+            ;;
+    esac
+}
+
+
+### Extract Debian kernel ABI from kernel package version
+kernel_abi_from_version(){
+    local VERSION="$1"
+
+    case "${VERSION}" in
+        *-cloud-amd64)
+            echo "${VERSION%-cloud-amd64}"
+            ;;
+        *-rt-amd64)
+            echo "${VERSION%-rt-amd64}"
+            ;;
+        *-amd64)
+            echo "${VERSION%-amd64}"
+            ;;
+        *-686-pae)
+            echo "${VERSION%-686-pae}"
+            ;;
+        *-686)
+            echo "${VERSION%-686}"
+            ;;
+        *-cloud-arm64)
+            echo "${VERSION%-cloud-arm64}"
+            ;;
+        *-rt-arm64)
+            echo "${VERSION%-rt-arm64}"
+            ;;
+        *-arm64)
+            echo "${VERSION%-arm64}"
+            ;;
+        *-common)
+            echo "${VERSION%-common}"
+            ;;
+        *)
+            echo "${VERSION%-*}"
+            ;;
+    esac
+}
+
+
+### List installed Debian kernel packages
+list_installed_kernel_packages(){
+    {
+        "${DPKG_QUERY}" -W -f='${db:Status-Abbrev}\t${binary:Package}\n' \
+            'linux-image-[0-9]*' \
+            'linux-image-unsigned-[0-9]*' \
+            'linux-headers-[0-9]*' \
+            2>/dev/null || true
+    } | awk '$1 == "ii" { print $2 }' | sort -u
+}
+
+
+### List residual Debian kernel packages in rc state
+list_rc_kernel_packages(){
+    {
+        "${DPKG_QUERY}" -W -f='${db:Status-Abbrev}\t${binary:Package}\n' \
+            'linux-image-[0-9]*' \
+            'linux-image-unsigned-[0-9]*' \
+            'linux-headers-[0-9]*' \
+            2>/dev/null || true
+    } | awk '$1 == "rc" { print $2 }' | sort -u
+}
+
+
+### List installed Debian kernel image versions
+list_installed_kernel_versions(){
+    {
+        "${DPKG_QUERY}" -W -f='${db:Status-Abbrev}\t${binary:Package}\n' \
+            'linux-image-[0-9]*' \
+            'linux-image-unsigned-[0-9]*' \
+            2>/dev/null || true
+    } | awk '$1 == "ii" { print $2 }' \
+      | while read -r PKG; do
+            pkg_to_kernel_version "${PKG}"
+        done \
+      | sort -V -u
+}
+
+
+### Build the list of kernels that should be kept
+build_keep_list(){
+    local INSTALLED_KERNELS=()
+    local VERSION=""
+    local ABI=""
+    local I=""
+
+    mapfile -t INSTALLED_KERNELS < <(list_installed_kernel_versions)
+
+    KERNELS_TO_KEEP=("${KERNELVER}")
+
+    for (( I=${#INSTALLED_KERNELS[@]}-1; I>=0 && ${#KERNELS_TO_KEEP[@]}<KEEP_KERNELS; I-- )); do
+        VERSION="${INSTALLED_KERNELS[$I]}"
+
+        if [ "${VERSION}" == "${KERNELVER}" ]; then
+            continue
+        fi
+
+        KERNELS_TO_KEEP+=("${VERSION}")
+    done
+
+    ABIS_TO_KEEP=()
+
+    for VERSION in "${KERNELS_TO_KEEP[@]}"; do
+        ABI="$(kernel_abi_from_version "${VERSION}")"
+        ABIS_TO_KEEP+=("${ABI}")
+    done
+}
+
+
+### Check if a package belongs to a kernel that should be kept
+is_kernel_to_keep(){
+    local PKG="$1"
+    local VERSION=""
+    local ABI=""
+    local KEEP=""
+
+    VERSION="$(pkg_to_kernel_version "${PKG}")"
+    ABI="$(kernel_abi_from_version "${VERSION}")"
+
+    for KEEP in "${KERNELS_TO_KEEP[@]}"; do
+        if [ "${VERSION}" == "${KEEP}" ]; then
+            return 0
+        fi
+    done
+
+    for KEEP in "${ABIS_TO_KEEP[@]}"; do
+        if [ "${ABI}" == "${KEEP}" ]; then
+            return 0
+        fi
+    done
+
+    return 1
+}
+
+
+### List old installed kernel packages
+list_old_installed_kernels(){
+    local PKG=""
+
+    while read -r PKG; do
+        if [ "${PKG}" == "" ]; then
+            continue
+        fi
+
+        if ! is_kernel_to_keep "${PKG}"; then
+            echo "${PKG}"
+        fi
+    done < <(list_installed_kernel_packages) | sort -u
+}
+
+
+### Build final package list
+build_purge_list(){
+    mapfile -t OLD_KERNELS < <(list_old_installed_kernels)
+    mapfile -t RC_KERNELS < <(list_rc_kernel_packages)
+
+    PKGS_TO_PURGE=("${OLD_KERNELS[@]}" "${RC_KERNELS[@]}")
+}
+
+
+### Print script summary
+print_summary(){
+    echo ""
+    echo "Running kernel : ${KERNELVER}"
+    echo "Keeping kernels: ${KERNELS_TO_KEEP[*]}"
+    echo "Keeping ABI    : ${ABIS_TO_KEEP[*]}"
+    echo ""
+
+    if [ "${#OLD_KERNELS[@]}" -gt 0 ]; then
+        echo "Old installed kernel packages:"
+        printf '  %s\n' "${OLD_KERNELS[@]}"
+    else
+        echo "[OK] No old installed kernel packages found."
+    fi
+
+    echo ""
+
+    if [ "${#RC_KERNELS[@]}" -gt 0 ]; then
+        echo "Residual rc kernel packages:"
+        printf '  %s\n' "${RC_KERNELS[@]}"
+    else
+        echo "[OK] No residual rc kernel packages found."
+    fi
+
+    echo ""
+}
+
+
+### Simulate package purge
+dry_run(){
+    if [ "${#PKGS_TO_PURGE[@]}" -eq 0 ]; then
+        echo "[OK] Nothing to purge."
+        exit 0
+    fi
+
+    "${APT_GET}" -s purge "${PKGS_TO_PURGE[@]}"
+}
+
+
+### Remove old kernel packages
+remove_kernels(){
+    local ANSWER=""
+
+    if [ "${#PKGS_TO_PURGE[@]}" -eq 0 ]; then
+        echo "[OK] Nothing to purge."
+        exit 0
+    fi
+
+    if [ "${ASSUME_YES}" != "yes" ]; then
+        read -r -p "Proceed with apt-get purge? [y/N] " ANSWER
+
+        case "${ANSWER}" in
+            y|Y|yes|YES)
+                ;;
+            *)
+                echo "Aborted."
+                exit 0
+                ;;
+        esac
+    fi
+
+    if [ "${ASSUME_YES}" == "yes" ]; then
+        "${APT_GET}" -y purge "${PKGS_TO_PURGE[@]}"
+    else
+        "${APT_GET}" purge "${PKGS_TO_PURGE[@]}"
+    fi
+    
+    echo ""
+    echo "Old kernels have been successfully plonked."
+}
+
+
+### Parse options
+while [ "$#" -gt 0 ]; do
+    case "$1" in
+        -l | --list)
+            ACTION="list"
+            ;;
+        -n | --dry-run)
+            ACTION="dry-run"
+            ;;
+        -r | --remove)
+            ACTION="remove"
+            ;;
+        -k | --keep)
+            shift
+
+            if ! [[ "${1:-}" =~ ^[0-9]+$ ]]; then
+                echo "[FAIL] --keep requires a number"
+                exit 1
+            fi
+
+            if [ "$1" -lt 1 ]; then
+                echo "[FAIL] --keep requires a number greater than zero"
+                exit 1
+            fi
+
+            KEEP_KERNELS="$1"
+            ;;
+        -y | --yes)
+            ASSUME_YES="yes"
+            ;;
+        -h | --help)
+            usage
+            exit 0
+            ;;
+        *)
+            usage
+            exit 1
+            ;;
+    esac
+
+    shift
+done
+
+
+### Main
+if [ "${ACTION}" == "" ]; then
+    usage
+    exit 1
+fi
+
+check_binary
+check_root
+build_keep_list
+build_purge_list
+print_summary
+
+case "${ACTION}" in
+    list)
+        exit 0
+        ;;
+    dry-run)
+        dry_run
+        ;;
+    remove)
+        remove_kernels
+        ;;
+esac
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