POSTIN

/bin/sh

 if ! grep '* * * * root /usr/bin/mrtg' /etc/crontab > /dev/null; then
  echo "" >> /etc/crontab
  echo "0-59/5 * * * * root /usr/bin/mrtg /var/www/html/mrtg/mrtg.cfg" >> /etc/crontab
 fi

POSTUN

/bin/sh

if [ "$1" = "0" ]; then
        grep -v '* * * * root /usr/bin/mrtg' /etc/crontab > /etc/crontab.new
        cp /etc/crontab.new /etc/crontab
fi