#!/bin/bash

# make sure sendmail works fine, E.g. ssmtp is very light and easy.
# crontab -e & add the following line to run every 6 hours:
# 0     */6   *   *   *     /home/miguel/bin/mail_apt_upgradable.sh

SUBJECT="$HOSTNAME : apt list --upgradeable"
MAIL="m.i@gmx.at"

if [ "$#" -ne 1 ]; then
    "$0" arg0 | sudo sendmail $MAIL
    exit
fi

echo "Subject: $SUBJECT"
echo "Hello Friend,"
echo 
echo "This is the automatic apt checker service."
echo 
sudo apt-get update  1> /dev/null 
echo "'apt update' exited with the return code: $?"
echo  
echo "'apt list --upgradable -a' produced the following output:"
echo 
echo "--- START ---"
apt list --upgradable -a  2>/dev/null
echo "--- END ---"
echo 
echo "Best regards,"
echo "Your FoolBot"