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).