Quickly Find Out What a Command Does Based on Its Name

man -f

If you know a command's name but don't know what it does, there's a quick and dirty way to find out without requiring you to actually open the man page for that command. Use the -f option (or --whatis), and the command's synopsis appears.

$ man -f ls ls (1)             - list directory contents 

Tip

Yes, the -f option, also known as --whatis, is the spitting image of the whatis command, which is examined in more detail later in this chapter.