How to use grep to match domain names?

Question

I have a list of urls like:

hxxp://url.com/subpage.html
hxxp://www.url2.com/index.php
hxxp://subdomain.url3.com/somepage.php
...

How can I use grep to match the domain names only?

All the urls have a / after the domain. And there are a lot of tlds, not sure how many, the list is quite big.

Solution

In order to use non-greedy regexes with grep you will need to use the -P option and the -o option outputs only the matching portion. You will also need to use lookarounds so that part of the match is not included in the output.

grep -Po '.*?//\K.*?(?=/)'

Example:

$ echo 'hxxp://subdomain.url3.com/somepage.php' | grep -Po '.*?//\K.*?(?=/)'
subdomain.url3.com

Comments

[Karl Bielefeldt]

That won't work for http://url.com/directory/page.html