du - print disk usage
du [-as] [-l n] dir ...
-a Give usage for all files -l List up to n levels of subdirectories -d Do not cross file system boundaries -s Summary only
du dir # List disk space used by files in dir du -s dir1 dir2 # Give summaries only du -d / # Show only the root device
Du examines one or more directories and prints the amount of space occupied by the files in those directories and their subdirectories.
df(1).