What is the unix command to see how much disk space there is and how much is remaining?

Question

I\'m looking for the equivalent of right clicking on the drive in windows and seeing the disk space used and remaining info.

Answer 1

All these answers are superficially correct. However, the proper answer is

 apropos disk   # And pray your admin maintains the whatis database

because asking questions the answers of which lay at your fingertips in the manual wastes everybody's time.