If found a decent little guide for using two command line utilities du and df.

  • du shows you the disk usage of a folder — that is, how much space the contents of a give folder are taking up.
  • df shows you the disk free space of your file system and gives the output in columns that indicate the size, used space, available space, and percentage of used space.

Check out How to find – Size of a directory & Free disk space for the guide.