Find out what a command does
At the command line, run:
This will give you a one-line summary of a command.
If whatis doesn't work, the whatis database may not be built yet. To build the whatis database, enter this:
I can't remember the name of the command I need
The apropos command searches a database of commands, using keywords:
Note that your keyword might not work. So try different keywords until it does!
If apropos does not work, you probably need to rebuild the whatis database with this command: