PeterWhen you're looking for some documentation and help about a specific command, man really is your best friend. Almost all the commands on your system will have a man page where you can look to find all sorts of information.
However, sometimes you can find more detailed manuals on GNU-based systems with the info command. It works slightly differently to man, but on some software, you will be able to access a much more detailed manual about a particular command or software package.
Using info is of course, frightfully easy:
$ info commandname
It doesn't always turn out what your looking for, but if you're left in the dark after using man, try info as well. Or the other way round. You decide.
