#!/bin/bash
# CheckKernel checks if Kernel was updated and not aktivated (rebooted)
#
# (c) GPL by Ulf Bartholomäus ub1x@gmx.net
VERSION="$( basename $0 ) Version 0.2.3 from 12.7.2021"
#
# Input:        1 parameter optional ("-d" = debug and "-v" = verbose / "-D" = Distro only / "-K" = running KernelVerion / "-N" = New Kernel Version)
# Output:       text messages and a kdialog if this is installed
# Returnvalue:	0 if Kernel OK and 10 if Kernel is changed
#
# ToDo:			Check if initrd and vmlinuz exists
#               cat /etc/issue
#               cat /proc/version
# Error:        inxi - hangs in a script:
#               MyDistro="$( eval inxi -xSz | grep Distro: | awk -F'Distro: '   '{print $2}' )"
#               https://github.com/smxi/inxi/issues/181
#
# Changes:
#	0.2.3:		Fix error => update in case only one Kernel is avaialble
#	0.2.2:		Fix error => new Kernel update: replace initrd with vmlinuz check
#	0.2.1:		added -D -K and -N option
#               Fixed error and exit with more than one /boot/initrd-* file
#	0.2.0:		InitKernel und VmlzKernel entfernt, 
#               [ $( ls -1 /boot/ | grep initrd- | wc -l ) -gt 1 ] && echo "** Error" || ls -1 /boot/ | grep initrd- | cut -d '-' -f 2,3,4
#               Some small changes and simplifications
#	0.1.9:		NewKernel erneut angepasstsys
#	0.1.8:		"==" -> "=" sowie kleinere Shönheitskorrekturen - sowie NewKernel mit awk statt cut
#	0.1.7:		remove "CheckKernel.sh: Zeile 33: lsb_release: Kommando nicht gefunden." 
#			and => -d = debaug
#	0.1.6:		if "lsb_release" not available use "cat /etc/*-release" info
#	0.1.5:		Fix trouble if NewKernel is empty
#	0.1.4:		Fix some errors
#	0.1.3:		Fix running and new kernel are equal but shown as different
#	0.1.2:		Remove "initrd-" from InitKernel
#	0.1.1:		Add Kernel Info in kdialog
#	0.1.0:		exchange some direct calls against definition
#				add check if new Kernel is in GRUB Config file
#	0.0.7:		read Kernel version from menu.lst
#	0.0.6:		add verbose mode
#	0.0.5:		syslog messages
#	0.0.4:		returnvalue if Kernel is changed is 10
#	0.0.3:		hostname in kdialog title
#	0.0.2:		kdialog output
#	0.0.1:		generation
#

DEBUG=""
MyDistro=""
MyKernel=""
NewKernel=""
InitKernel=""

if [ $# -gt 0 ] && [ "$1" = "-d" ] ; then
    DEBUG="1"
    echo -e "\t<${VERSION}>"
    shift
fi

MyDistro="$( cat /proc/version )"
MyDistro="${MyDistro/*;/}" # remove first string till ";"
MyDistro="${MyDistro/)*/}" # remove anything behind ")"
MyDistro="${MyDistro/# /}" # remove blanks in the beginning

if [ $# -gt 0 ] && [ "$1" = "-D" ] ; then
    echo "${MyDistro}"
    exit
fi

MyKernel="$( uname -r )"

if [ $# -gt 0 ] && [ "$1" = "-K" ] ; then
    echo "${MyKernel}"
    exit
fi

InitKernel="$( ls -1tr /boot/ | grep 'vmlinuz-' )"
if [ $( echo "${InitKernel}" | wc -l ) -ge 1 ] ; then
    # If To much Kernels - exit
    # use only the last listed kernel (hopfully the newest)
    NewKernel="${InitKernel/*vmlinuz-/}"
else
    # no "vmlinuz" entry
    [ ${DEBUG} ] && echo "** Error: /boot/vmlinuz-* is missing <${InitKernel}>"
#    exit 10
    NewKernel="Missing /boot/vmlinuz-*"
fi

if [ $# -gt 0 ] && [ "$1" = "-N" ] ; then
    echo "${NewKernel}"
    exit
fi

if [ ${DEBUG} ] ; then
  echo -e "* Debug Info *\n\t MyDistro=${MyDistro},\n\t MyKernel=${MyKernel},\n\t InitKernel=${InitKernel},\n\t NewKernel=${NewKernel}!"
  [ "x${MyKernel}" = "x${NewKernel}" ] && echo -e "*\t(${MyKernel}) = (${NewKernel})" || echo -e "***\t(${MyKernel}) != ${NewKernel} !!!"
  echo "*"
fi

if [ "x${MyKernel}" = "x${NewKernel}" ] ; then 
  if [ $# -gt 0 ] && [ "$1" = "-v" ] ; then
	echo -e "\t*** Distro: ${MyDistro} \tKernel ${MyKernel} \t$( date "+%X / %d.%m.%Y" ) \t*** Kernel OK ***"
  else
	echo "*** Kernel OK  (${MyKernel})"; 
  fi
else 
  if ( [ $# -gt 0 ] && [ "$1" == "-v" ] ) ; then
	echo -e "\t*** Distro: ${MyDistro} \tKernel ${MyKernel} \t$( date "+%X / %d.%m.%Y" ) \t*** NEW Kernel ${NewKernel}!!! ***"
  else
	MsgTxt="*** Kernel Updated from ${MyKernel} to ${NewKernel}! => please reboot"
	echo "${MsgTxt}";
	logger -t $( basename $0 ) "${MsgTxt}"
	if [ $# -eq 0 ] && [ -e $( which kdialog 2>> /dev/null ) ] ; then
	  kdialog --title "*** $( hostname ) ***" --error "${MsgTxt}"  >> /dev/null 2>> /dev/null
	fi
  fi
fi