Ubuntu Kernel Cleanup

README.md

Ubuntu Kernel Cleanup

General

This script is used to remove old kernels cluttering /boot on Ubuntu systems. The following kernels are preserved:

• The running kernel
• The latest kernel from each major version

This means that, if for example linux-image-server and linux-image-generic-lts-quantal are installed on an Ubuntu Precise system, the running kernel, the latest 3.2.0 kernel and the latest 3.5.0 kernel are preserved. All other kernels and header files are purged.

Install

• Copy kernel-cleanup to /usr/local/sbin and make it executable
• Copy kernel-cleanup_dpkg-hook to /etc/apt/apt.conf.d/98-kernel-cleanup

kernel-cleanup

#!/bin/bash

### FUNCTIONS ###

getcurrentkernel() {
  uname -r
}

getcurrentmajorkernel() {
  uname -r | grep -oE '[0-9]+\.[0-9]+\.[0-9]+-[0-9]+'
}

getinstalledmajorkernels() {
  dpkg -l | grep -oE '^ii  linux-image-[0-9]+\.[0-9]+\.[0-9]+' | grep -oE '[0-9]+\.[0-9]+\.[0-9]+' | sort | uniq
}

getlatestversion() {
  dpkg -l | grep -E "^ii  linux-image-$1" | awk 'END{print $2}' | grep -oE '[0-9]+\.[0-9]+\.[0-9]+-[0-9]+'
}

getexcludelist() {
  excludelist=$(getcurrentmajorkernel)
  for kver in $(getinstalledmajorkernels)
  do
    excludelist+="|"$(getlatestversion ${kver})
  done
  echo ${excludelist}
}

getremovelist() {
  removelist=$(dpkg -l | awk /'^(ii|rc)  linux-(image|headers)-([a-z]+-)?[0-9]+\.[0-9]+\.[0-9]+/ {print $2}' | grep -vE $(getexcludelist))
  echo ${removelist}
}

disablegrubhook() {
  [ -d /etc/kernel.bak ] || mkdir /etc/kernel.bak
  [ -f /etc/kernel/postrm.d/zz-update-grub ] && mv -f /etc/kernel/postrm.d/zz-update-grub /etc/kernel.bak
  [ -f /etc/kernel-img.conf ] && mv -f /etc/kernel-img.conf /etc/kernel.bak && sed 's/^\(postrm_hook   = update-grub\)$/#\1/' /etc/kernel.bak/kernel-img.conf > /etc/kernel-img.conf
}

enablegrubhook() {
  [ -f /etc/kernel.bak/zz-update-grub -a ! -f /etc/kernel/postrm.d/zz-update-grub ] && mv /etc/kernel.bak/zz-update-grub /etc/kernel/postrm.d
  [ -f /etc/kernel.bak/kernel-img.conf ] && mv -f /etc/kernel.bak/kernel-img.conf /etc/kernel-img.conf
  rm -fr /etc/kernel.bak
}

### MAIN SCRIPT ###

removelist=$(getremovelist)
[[ -z ${removelist} ]] && exit 0

echo "Cleanup of old kernels ..."

disablegrubhook

echo ${removelist} | xargs dpkg -P

enablegrubhook
update-grub

kernel-cleanup_dpkg-hook

DPkg::Post-Invoke {"/usr/local/sbin/kernel-cleanup"}