And I am not talking about google here. Remember Linux was popular among geek community much before the availability of 1.5 gig of data to all of us. Linux has two important commands to get help on any command. (Did you know that even Windows OS has help command (help cmdname)?) Anyways, if you want a long description of any command, you use man pages or manual pages. And if you just want to know what is that command, you just say that - whatis . First let us look at man command. To see the manual page of ls command, you type man ls Now this is what your system gives you You can keep two terminals open and see man page and experiment with command. But if you are impatient, you just want to know what the command does, then use whatis . And if you have no idea what the command name is, but it must copy, you can use apropos copy. apropos will search for all command whose description has copy in them and display them as can be seen in the diagram.