#!/bin/bash
# Created by Ian Perry 2021-02-24

usage() {
	echo " check_updates - Ubuntu Check for System Updates Script"
	echo ""
	echo " Usage: check_updates [ -d ]"
	echo ""
    echo "      -d  enable debugging output"
}

debug=0

while getopts ":h:d" myarg "$@"
do
  case $myarg in
    h)	usage
        exit 3
        ;;
    d)  debug=1;
        ;;
    *)
  esac
done

# Function for debugging output
function dout() {
    if [[ $debug == "1" ]] ; then
        echo "$1"
    fi
}

# Uses a dry run of apt-get upgrade to count the number of security and non-security updates.
# Note: Once apt has been updated on all servers to something more stable (i.e. not running outdated on Ubuntu 14.04)
# this should be modified to the following due to proper standards and speed:
# nonSecUpdatesAvail=$(apt list --upgradable --quiet=2 | grep -vi security | wc -l)
# secUpdatesAvail=$(apt list --upgradable --quiet=2 | grep -i security | wc -l)
updatesAvail="$(apt-get upgrade -s --quiet=2 2>&1)"
nonSecUpdatesAvail=$(echo $updatesAvail | sed 's/Conf/\n&/g' | sed 's/Inst/\n&/g' | grep -vi security | grep ^Inst | wc -l)
secUpdatesAvail=$(echo $updatesAvail | sed 's/Conf/\n&/g' | sed 's/Inst/\n&/g' | grep -i security | grep ^Inst | wc -l)

dout "Security updates available: $secUpdatesAvail."
dout "Non-Security updates available: $nonSecUpdatesAvail."

rebootRequiredFlag=0 # Default

# Check to see if a reboot is needed.
if [ -e /var/run/reboot-required ]; then
	dout "Reboot required."
	rebootRequiredFlag=1
else
    dout "No reboot required."
fi

textString=""
exitStatus=0

if [[ $secUpdatesAvail > 0 ]]; then
    textString+="CRITICAL - "
    exitStatus=2
elif [[ $secUpdatesAvail == 0 ]]; then
    textString+="OK - "
else
    textString+="UNKNOWN - "
    exitStatus=3
fi

if [[ $rebootRequiredFlag == 1 ]] ; then
    textString+="REBOOT REQUIRED - "
elif [[ $rebootRequiredFlag == 0 ]]; then
    :
else
    textString+="REBOOT STATUS UNKNOWN - "
    exitStatus=3
fi

textString+="Security updates available: $secUpdatesAvail. Non-Security updates available: $nonSecUpdatesAvail."
echo $textString
exit $exitStatus