#!/bin/bash

#
## apt-check
##
## A simple shell script to check debian machines for updates using the apt-get
## utility. If there are no updates available and no error occurred, there is
## also no output. This is for easy use in /etc/crontab
##
## Explanation: If you start a script by using /etc/crontab, every output is
## sent to you by mail. If there is no output, there is also no mail. So you
## can use this script in /etc/crontab and if anything happend you will
## receice a mail.
##
## Here is a example how to include this script to /etc/crontab:
## 0 */2 * * * root /usr/local/bin/apt-check
##
## This script has NO parameters.
##
## Exit-Code 0 = No updates available (no output - for use in cronjob)
## Exit-Code 1 = New updates available (see output, STDOUT)
## Exit-Code 2 = An error occurred (see output, STDOUT)
##

##
## Configuration
##

# The given message is included in every output. You can use it to identify
# different machines (if you have a log), when you get a message from the
# script
MACHINE="Server: bierhasser.dyndns.org" # First line of any output

# Dont chance if apt-get is located in /usr/bin (this is default).
# use 'whereis apt-get' to check.
APTGETCMD="/usr/bin/apt-get" # Pfad und Name des apt-get binary

## ----------------------------------------------------------------------------
## DON'T EDIT ANYTHING BELOW THIS LINE! DON'T EDIT ANYTHING BELOW THIS LINE!
## ----------------------------------------------------------------------------

#
# UPDATE
#
export LANG=C
APTOUTPUT=`$APTGETCMD update 2>&1`
EXITCODE=$?
if [[ "$EXITCODE" -ne "0" ]]
then
echo "$MACHINE";
echo "WARNING: There were errors while updating the package list."
echo " Possibly there is no response from an update server"
echo " or any other failure was happening."
echo
echo "----------------------------------------------------------------"
echo "$APTOUTPUT"
echo "----------------------------------------------------------------"
exit 2
fi

#
# DIST-UPGRADE
#

APTOUTPUT=`$APTGETCMD -s -u safe-upgrade 2>&1`
PACKAGECOUNT=`echo "$APTOUTPUT" | grep "packages upgraded" | perl -pe "s/^([0-9]+).*$/\1/g" 2>&1`
if [[ "$PACKAGECOUNT" -ne "0" ]]
then
echo "$MACHINE";
echo "Updates are available. Please install them as soon as possible."
echo
echo "----------------------------------------------------------------"
echo "$APTOUTPUT"
echo "----------------------------------------------------------------"
exit 1
fi