check_ip

#!/bin/bash

FILE=~/.ip
IP=$(curl -s ifconfig.co)
OLD=$(cat "$FILE");

if [[ "$OLD" == "$IP" ]]; then
  echo "No IP change";
else
  echo "IP changed";
  echo $IP > $FILE;
  ./update_bind9 $IP
fi

crontab

*/5 * * * * /root/scripts/check_ip >/dev/null 2>&1

update_bind9

#!/bin/bash
IP=$1

sed "s/IP/$IP/" /etc/bind/zones/db.default.mask | tee /etc/bind/zones/db.default
service bind9 restart