#!/bin/bash if [ $# != 1 ]; then echo -e "Usage:\n $./lookup.sh wordpress\n $./lookup.sh ghs\n"; exit 1; fi while read line do host=$( echo "$line" | grep -oE "[a-z0-9]([a-z0-9_\.\-]*[a-z0-9])?\.[a-z]{2,3}" | grep -vE "dot$|htm$|php$" ); [ "$host" ] && [ "$(nslookup $host | grep $1)" ] && echo $host; done < "list.txt"