run as `./nslookupAlert.sh ${domain}` on macos to receive an alert when a domain DNS is resolved

nslookupAlert.sh

#!/bin/bash

domain=$1
echo -ne "Looking up $domain DNS: "

while true; do
  nslookup $domain | grep -q "find"
  retVal=$?
  if [ $retVal -ne 0 ]; then
    ip=$( nslookup $domain | awk -F': ' 'NR==6 { print $2 } ')
    echo "$domain found at $ip"
    osascript -e "tell app \"System Events\" to display dialog \"$domain found at $ip\"" >/dev/null
    break
  else
    echo -ne "."
  fi
  sleep 5
done