
The option `du -s` is equivalent to `du -d0`. The former is a POSIX standard (IEEE Std 1003.1-2008), whereas the latter is a BSD extension. From the BSD man page: `-s Display an entry for each specified file. (Equivalent to -d 0)` From SUSv4: `-s Instead of the default output, report only the total sum for each of the specified files.` http://pubs.opengroup.org/onlinepubs/9699919799/utilities/du.html Closes Homebrew/homebrew#16516. Signed-off-by: Charlie Sharpsteen <source@sharpsteen.net>