I see numbers in parentheses after program names and it confuses me. For example, perldoc mentions that perl grep is "similar in spirit to, but not the same as, grep(1) and its relatives."
What does the (1) signify? In there a grep(2)? Where is this documented?
I see manual pages that refer to the numbers as well but I don't know what the numbers mean or how to use them. I can't type "man grep(1)" for instance.
