Convert list of domains to IPs using dig

domainstoips.sh

#!/bin/sh
# call with domaintoips.sh <domain> <list of subdomains.txt>

ulimit -n 800000
while read -r domain; do dig +short $domain | grep -v '[[:alpha:]]' | sort -u >> $1-ipf.txt; done < $2
cat $1-ipf.txt | anew $1-ipz.txt