Question

I have a file that contains some text like:

aaa.co
bbb.com
ccc.net
sss.co.uk

I need to extract the *.co.* and *.com.* and put them in another file. I used the following to extract the *.com.* but how can I make extracting *.com.* and *.co.* in one command instead of performing them separately ?

egrep -io '[a-z0-9\-]+\.com(\.[a-z]{2})?' input.txt | sed -e 's/www.//' | sort | uniq >output.txt

Input file example:

aaa.co
bbb.com
ccc.net
sss.co.uk 

Result file:

co
com

Answer 1

just make the m in com optional

egrep -io '[a-z0-9\-]+\.co(m)?(\.[a-z]{2})?' input.txt | sed -e 's/www.//' | sort | uniq >output.txt

edit:
you could also drop sed and uniq

awk 'match($0, "(www\\.)?([a-z0-9\\-]+\\.com?(\\.[a-z]{2})?)", r) { print r[2] }' input.txt | sort -u 

edit:
another way to loose sed and uniq

grep -oP '^(www\.)?\K[a-z0-9\-]+\.com?(\.[a-z]{2})?(?=)$' input.txt | sort -u