The man tool allows you to explore the various utilities of the Shell. To search for more information about a command, just write

man command-name

As result, a new session will be opened with information about the command you have typed (and more specifically about its functions and flags).
Using some flags, you can obtain with this command the same results you get when you use other commands.

Flags

  • -k: returns the equivalent of apropos
  • -f: returns the equivalent of whatis