for loop to retrieve IPs using nslookup

I had to decommission a bunch of servers for which I didn’t have an IP list, needed for the paperwork.

Luckily, we still had the DNS records for those machines and, using a for loop and the almighty awk, I managed to retrieve all the information I needed:

for h in `cat hostname.list`; do nslookup $h | grep ^Name -A1 | awk '{print $2}'; echo; done > ip.list

This one-liner will output the IP and the corresponding hostname in a file.