How do you extract IP addresses from files using a regex in a linux shell?

Question

How to extract a text part by regexp in linux shell? Lets say, I have a file where in every line is an IP address, but on a different position. What is the simplest way to e

Answer 1

I wrote a little script to see my log files better, it's nothing special, but might help a lot of the people who are learning perl. It does DNS lookups on the IP addresses after it extracts them.