df is a great tool for checking the amount of free space on a disk (and the amount that’s taken). df has a number of options for ways to view the output and can even look at free iNodes and blocks rather than just showing free space. However, df is going to come up short if you’re hunting for where all your free space went within a given volume. For this, look to du. du is a great tool for checking disk utilization at more of a directory level. For example, the following command will show you how much space is being taken up by each application in the the…