5.3.2 Displaying Directory Usage (du)
You can use du to display the usage of a directory
and all its subdirectories in 512-byte blocks; that is, units of 512 bytes
du shows you the disk usage in each subdirectory.
To get a list of subdirectories in a filesystem, cd to
the pathname associated with that filesystem, and run the following pipeline:
This pipeline, which uses the reverse and numeric options of the sort command, pinpoints
large directories. Use ls -l to examine
the size (in bytes) and modification times of files within each directory.
Old files, or text files over 100 Kbytes, often warrant storage offline.