The man program provides an interface to the online documentation, it is available as a text only version and an X-Windows version called xman. To find out more about a command, we can just type man followed by the command's name:
$ man man man(1) man(1) NAME man - format and display the on-line manual pages manpath - determine user's search path for man pages SYNOPSIS
To get information without knowing the command, we can use the keyword option:
$ man -k manual man (1) - Format and display the on-line manual pages whereis (1) - Locate binary, manual, and or source for program xman (1) - Manual page display program for the X Window System $
This gives us a list of applicable manual pages.