This is the man page: http://linuxcommand.org/lc3_man_pages/grep1.html . Try -v.
Did you know man is available in Unix also? No need to go the web to find out.
I have a configuration file which is a simple text. I want to list some configuration line but except some sitring. How can I use Linux grep to exclude and search for given strings? Thanks in advance for your help!