Extracting a part of String using grep/sed

Question

I have a file in linux with similar entries as below

dn: CN=HP_NetworkSupport,OU=groups,DC=HDFCSLDM,DC=COM
dn: CN=Review users,OU=groups,DC=HDFCSLDM,DC=COM
<         


        

Answer 1

This is one way with lookahead:

grep -Po '(?<=CN=)[^,]*' file > new_file

It gets all text from CN= (not included) until it finds a comma ,. The idea of [^,]* is to fetch any character that is not a comma.

Test

$ grep -Po '(?<=CN=)[^,]*' file
HP_NetworkSupport
Review users