#!/bin/bash
# Author: Dean Wilson ; License: GPL
# Project Home: http://www.unixdaemon.net/
# Version: 0.3
# Fixed a bug when only a single package needs upgrading.
# Now allows a single package to create a crit - from Bartlomiej Konarski

binaries=$(cat<<all_required_binaries
  basename
  apt-get
  sudo
all_required_binaries)

# app settings
APPNAME=$(basename $0)
VERBOSE=0         # be quiet by default

# sanity check. - check all binaries are present and usable
for required_binary in $binaries; do
  which $required_binary > /dev/null
  if [ "$?" != '0' ];then
    printf "$APPNAME: No usable '$required_binary' in '$PATH'\n"
    exit 3
  fi
done

#################################################################
# the scripts usage information
#################################

usage () {

cat<<EOU
$APPNAME - Copyright (c) 2006 Dean Wilson Licensed under the GPL

This program checks for Debian packages needing updates and informs
Nagios of the results.

Usage: $APPNAME

Required Options:
 -w
    Exit with WARNING status if INTEGER or more packages need to be updated
 -c
    Exit with CRITICAL status if INTEGER or more packages need to be updated

Optional Options:
 -v
   Displays all packages that need updating. This may cost a lot of screen estate
   in the Nagios frontend.
 -h
    This help and usage information.

Notes:
 The warning level must be lower than critical level.

Examples:
 $APPNAME -w 1 -c 10
   Checks the packages and warns on 1-9 needing upgrades, criticals on 10 or more.
 $APPNAME -w 1 -c 10 -v
   Same as above but the output contains the package names


EOU
exit 3
}

#################################################################
# process script arguments  - : means left option takes an argument.
#################################

while getopts "w:c:vh" option
do
  case $option in
    w ) WARN_THRESH=$OPTARG ;;
    c ) CRIT_THRESH=$OPTARG ;;
    v ) VERBOSE=1           ;;
    h ) usage               ;;
  esac
done

# ensure we got a warning and a crit
if [ -z "$WARN_THRESH"  ] || [ -z "$CRIT_THRESH" ];then
  echo "You must supply both -w int and -c int"
  exit 3
fi

# check that crit is higher than warn or complain
if [ "$WARN_THRESH" -gt "$CRIT_THRESH" ];then
  echo "Warning level must be lower than crit level."
  exit 3
fi

#################################################################
# update the package list
#################################

sudo apt-get update > /dev/null

if [ "$?" -ne 0 ];then
  echo "apt-get update failed."
  exit 3
fi

#################################################################
# get the packages that need upgrading
#################################

# grab the package names in a single line
PACKAGES=$(sudo apt-get upgrade -s | grep ^Inst | cut -f2 -d ' ' | tr '\n' ' ')

# does this capture the right return or is it picking up the tr ? TODO
if [ "$?" -ne 0 ];then
  echo "apt-get upgrade -s failed."
  exit 3
fi

# get the number of packages that need updating
NUM_PKGS=$(echo "$PACKAGES" | grep -o ' ' | wc -l)

#################################################################
# print the output and give a return code for nagios
#################################

if [ "$NUM_PKGS" -ge "$CRIT_THRESH" ];then
  printf "CRIT: - $NUM_PKGS packages need updating"
  if [ "$VERBOSE" -ne 0 ];then
    printf " - $PACKAGES"
  fi
  printf "\n"
  exit 2
elif [ "$NUM_PKGS" -ge "$WARN_THRESH" ];then
  printf "WARN: - $NUM_PKGS packages need updating"
  if [ "$VERBOSE" -ne 0 ];then
    printf " - $PACKAGES"
  fi
  printf "\n"
  exit 1
else
  echo "OK: No packages need updating"
  exit 0     # no problems - nagios goes green
fi