dnssrv="dns-server"
zone="example.com"
ttl="86400"
ip=$(ifconfig eth0 | grep "inet " | awk '{gsub("addr:","",$2);  print $2 }' )
pi=$(echo $ip | awk 'BEGIN{FS="."}{print $4"."$3"."$2"."$1".in-addr.arpa"}')
ptr=$(host $HOSTNAME $dnssrv | grep "has address" | awk '{print $4}')

updatedns(){
(
  echo "server ${dnssrv}"
  echo "$@"
  echo "send"
  echo "quit"
) | /usr/bin/nsupdate

}

if [ ! -z "$ptr" ] ; then
  rtp=$(echo $ptr | awk 'BEGIN{FS="."}{print $4"."$3"."$2"."$1".in-addr.arpa"}')
  echo "reverse record found, deleting $rtp ..."
  updatedns update delete $rtp
fi

echo "deleting $HOSTNAME.${zone}"
updatedns update delete $HOSTNAME.${zone}
echo "Adding record for $pi"
updatedns update add $pi ${ttl} IN PTR $HOSTNAME.${zone}
echo "Adding record for $HOSTNAME.${zone}"
updatedns update add $HOSTNAME.${zone} ${ttl} A ${ip}