#! /bin/bash
# encoding: utf-8
# vim: se ts=2 sw=2 et:

# menageatator: Remove unneeded linux kernel from debuntu systems
# http://schplurtz.free.fr/wiki/schplurtziel/menageatator
#  
#               Copyright Schplurtz Le Déboulonné, 2016, 2017, 2019
#  
#                  Schplurtz le Déboulonné <Schplurtz@laposte.net>
#  
#                FRENCH                |            ENGLISH
#  ------------------------------------+--------------------------------------
#  Ce logiciel est un programme        | This software is a computer program
#  informatique servant à supprimer    | whose purpose is to automatically
#  automatiquement les noyaux non      | remove unused kernels from ubuntu
#  utilisés des systèmes ubuntu ou     | or Debian GNU/Linux systems.
#  debian GNU/linux.                   |
#                                      |
#  Ce logiciel est régi par la licence | This software is governed by the
#  CeCILL soumise au droit français et | CeCILL license under French law and
#  respectant les principes de         | abiding by the rules of
#  diffusion des logiciels libres.     | distribution of free software.  You
#  Vous pouvez utiliser, modifier      | can  use, modify and/ or
#  et/ou redistribuer ce programme     | redistribute the software under the
#  sous les conditions de la licence   | terms of the CeCILL license as
#  CeCILL telle que diffusée par le    | circulated by CEA, CNRS and INRIA
#  CEA, le CNRS et l'INRIA sur le site | at the following URL
#  "http://www.cecill.info/".          | "http://www.cecill.info/".
#                                      |
#  En contrepartie de l'accessibilité  | As a counterpart to the access to
#  au code source et des droits de     | the source code and  rights to
#  copie, de modification et de        | copy, modify and redistribute
#  redistribution accordés par cette   | granted by the license, users are
#  licence, il n'est offert aux        | provided only with a limited
#  utilisateurs qu'une garantie        | warranty  and the software's
#  limitée.  Pour les mêmes raisons,   | author,  the holder of the economic
#  seule une responsabilité restreinte | rights,  and the successive
#  pèse sur l'auteur du programme,  le | licensors  have only  limited
#  titulaire des droits patrimoniaux   | liability.
#  et les concédants successifs.       |
#                                      |
#  A cet égard  l'attention de         | In this respect, the user's
#  l'utilisateur est attirée sur les   | attention is drawn to the risks
#  risques associés au chargement,  à  | associated with loading,  using,
#  l'utilisation,  à la modification   | modifying and/or developing or
#  et/ou au développement et à la      | reproducing the software by the
#  reproduction du logiciel par        | user in light of its specific
#  l'utilisateur étant donné sa        | status of free software, that may
#  spécificité de logiciel libre, qui  | mean  that it is complicated to
#  peut le rendre complexe à manipuler | manipulate,  and  that  also
#  et qui le réserve donc à des        | therefore means  that it is
#  développeurs et des professionnels  | reserved for developers  and
#  avertis possédant  des              | experienced professionals having
#  connaissances  informatiques        | in-depth computer knowledge. Users
#  approfondies.  Les utilisateurs     | are therefore encouraged to load
#  sont donc invités à charger  et     | and test the software's suitability
#  tester  l'adéquation  du logiciel à | as regards their requirements in
#  leurs besoins dans des conditions   | conditions enabling the security of
#  permettant d'assurer la sécurité de | their systems and/or data to be
#  leurs systèmes et ou de leurs       | ensured and,  more generally, to
#  données et, plus généralement, à    | use and operate it in the same
#  l'utiliser et l'exploiter dans les  | conditions as regards security.
#  mêmes conditions de sécurité.       |
#                                      |
#  Le fait que vous puissiez accéder à |  The fact that you are presently
#  cet en-tête signifie que vous avez  |  reading this means that you have
#  pris connaissance de la licence     |  had knowledge of the CeCILL license
#  CeCILL, et que vous en avez accepté |  and that you accept its terms.
#  les termes.                         |

# Yeah I know. Could use ruby/perl/ocam/lua/python/whatever and less pipes.
# Could use array, associative arrays etc... Just prefering simplicity,
# clarity and possibility to run with dumb^Wsimple shells. 

# 
# Whatever happens :
#   keep the current kernel
#   keep the most recent kernel correctly installed
#   keep all kernels that are on hold
# if current = most recent, keep the next most recent kernel
# 
# remove anything else.


IFS="$(printf ' \t')
"
# /sbin and /usr/sbin are usually not in cron PATH. add them
# if they're not present as dpkg will need commands there.
case "$PATH" in
(*:/usr/sbin|/usr/sbin:*|*:/usr/sbin:*) : ;;
(*) PATH="${PATH}:/usr/sbin" ;;
esac
case "$PATH" in
(*:/sbin|/sbin:*|*:/sbin:*) : ;;
(*) PATH="${PATH}:/sbin" ;;
esac

set -e # Stop on any error.

version() {
  sed -e "s/${1}-//"           # remove prefix
}
no_suffix() {
  sed -e 's/-[a-zA-Z_]*$//'    # remove suffix. (-generic, -lowlatency etc...)
}

reject() {
  grep -v "$@"
}

dpkg_query() {
# dpkg sorts alphabetically. to avoid problematic order, explicitly sort
# on version number.
#            before sorting          |           After sorting
# ii  linux-image-3.13.0-100-generic | ii  linux-image-3.13.0-95-generic
# ii  linux-image-3.13.0-101-generic | ii  linux-image-3.13.0-98-generic
# ii  linux-image-3.13.0-95-generic  | ii  linux-image-3.13.0-100-generic
# ii  linux-image-3.13.0-98-generic  | ii  linux-image-3.13.0-101-generic

# old dpkg-query (from ubuntu 12.04 lucid for example) don't support
# ${db:Status-Abbrev}. We have to use ${Status} that's a real pain.
# We have to convert things like "deinstall ok config-files" to
# "rc "
# examples :
#     install ok installed linux-image-3.2.0-23-generic
#     unknown ok not-installed linux-image-3.2.0-23-generic
#     deinstall ok config-files linux-image-3.2.0-23-generic
#     hold ok installed linux-image-3.2.0-23-generic
# The sed script does this :
#   1) rewrite deinstall to removed
#   2) replace the first 3 word by their initials in changing order
#      fe "unknown ok not-installed" becomes "uno" (2 and 3 are swapped)
#   3) in 3rd column, replace "o" by " " 
# Also we are not interested in uninstalled kernels, so we filter
# out the kernels that dpkg has never touched : /^un /
  
  dpkg-query -W -f '${Status} ${package}\n' "$@" 2>/dev/null |
    sed -e 's/^deinstall/removed/
            s/^\(.\)[^ ]* *\(.\)[^ ]* *\(.\)[^ ]* */\1\3\2 /
            s/^\(..\)o/\1 /
           ' |
    reject '^un ' |
    sort -k 2,2V # always return list sorted by version number
}

_apt_get() {
  # args >&2 apt-get "$@"
  apt-get "$@"
}
ARGV=( "$@" ) # keep command line args for final apt-get command...

        linux_vers_tpl='[0-9]*.[0-9]*.[0-9]*-[0-9]*'
      linux_images_tpl="linux-image-${linux_vers_tpl}"
linux_images_extra_tpl="linux-image-extra-${linux_vers_tpl}"
     linux_headers_tpl="linux-headers-${linux_vers_tpl}"
     linux_modules_tpl="linux-modules-${linux_vers_tpl}"

# list of all linux-image packages dpkg is aware of
linux_img=$( dpkg_query "$linux_images_tpl" )

# Get the list of packages NOT to remove :
# onhold, current, latest, almost_latest
onhold= current= latest= almost_latest=

current=$(                        # This one is easy.
  uname -r |                      # get current version
  no_suffix                       # just the version, not the kind
)

onhold=$(
  echo "$linux_img" |             # list linux images
  grep ^h |                       # keep only those on hold
  awk '{ print $2 }' |            # keep package name only
  version linux-image |           # just need the version part of the name
  no_suffix                       # just the version, not the kind
)

latest=$(
  echo "$linux_img" |             # list linux images
  grep ^.i |                      # only consider correctly installed packages
  tail -1  |                      # keep last one
  awk '{ print $2 }' |            # keep package name only
  version linux-image |           # just need the version part of the name
  no_suffix                       # just the version, not the kind
)

if test "$latest" = "$current"
then
  almost_latest=$(
    echo "$linux_img" |           # list linux images
    grep ^.i |                    # only consider correctly installed packages
    tail -2  |                    # keep last two
    head -1  |                    # keep first one (that is the 2nd most recent)
    awk '{ print $2 }' |          # keep package name only
    version linux-image |         # just need the version part of the name
    no_suffix                     # just the version, not the kind
  )
fi

# build list and (grep -e args) of kernels to keep
set -- 
for version in $onhold $current $latest $almost_latest
do
  set -- ${1+"$@"} -e "$version"
done
#OFF#green="$*"
#OFF## 32 vert; 33 brown
#OFF#set -- -e '/^h/s/.*/&/' $(
#OFF#  printf '%s\n' $green |
#OFF#  awk '
#OFF#    /^-e$/ { print; next }
#OFF#    { print "/" $1 "/s/.*/&/" }
#OFF#  '
#OFF#  )
#OFF#
#OFF#set -x
#OFF#  dpkg_query \
#OFF#    "$linux_images_tpl" \
#OFF#    "$linux_images_extra_tpl" \
#OFF#    "$linux_headers_tpl" |        # list linux images, images-extra, headers
#OFF#    sed "$@"
#OFF#
#OFF#exit

# build list of kernels to remove
set -- $(
  dpkg_query \
    "$linux_images_tpl" \
    "$linux_images_extra_tpl" \
    "$linux_headers_tpl" \
    "$linux_modules_tpl" |        # list linux images, images-extra, headers, modules
  reject '^h' |                   # filter out packages on hold
  reject "$@" |                   # filter out those we keep
  awk '{ print $2 }'              # just keep name
)

# If there are kernels to remove, remove them
{ test $# -gt 0 && _apt_get "${ARGV[@]}" purge "$@" ; } || :

# Given this list of kernel,
# ii  linux-image-3.13.0-93-generic
# ii  linux-image-3.13.0-95-generic
# ii  linux-image-3.13.0-96-generic
# ii  linux-image-3.13.0-98-generic
# ii  linux-image-3.13.0-100-generic
# ii  linux-image-3.13.0-101-generic
# ii  linux-image-3.13.0-103-generic
#
# and if we are running 3.13.0-95, this script
# performs these removal :
# apt-get purge linux-image-3.13.0-93-generic linux-image-3.13.0-96-generic linux-image-3.13.0-98-generic linux-image-3.13.0-100-generic linux-image-3.13.0-101-generic