du(1) - Unix First Edition Manual Page
11/3/71DU (I)

NAME du -- summarize disk usage
SYNOPSIS du [--s] [--a] [name...]
DESCRIPTION du gives the number of blocks contained in allfiles and (recursively) directories within each

specified directory or file name. If name is missing, "."is used.

The optional argument --s causes only the grand total to begiven. The optional argument --a causes an entry to be generated for each file. Absence of either causes an entryto be generated for each directory only.

A file which has two links to it is only counted once.
BUGS Files at the top level (not under --a option) are notlisted.

Removable file systems do not work correctly since i--numbers may be repeated while the corresponding files are distinct. Du should maintain an i--number list per rootdirectory encountered.