I have discovered that, when your PHP script runs on your WebHosting web site certain "well-known" directories magically appear. The directory names are:

bin dev

etc home

usr var

The FileManager or FTP clients do not show these directories but a PHP script can list their contents.

I also discovered that, if I created a subdirectory named "usr", for example, my PHP scripts could not see any files that I placed in that directory. Instead, the PHP script would see these directories:

mode       lnk    UID     GID      size    time      name
drwxr-xr-x  2       0       0       512 Nov 08 05:48 bin
drwxr-xr-x  7       0       0      2560 Jan 20 09:20 lib
drwxr-xr-x  2       0       0       512 Aug 01 07:49 php
drwxr-xr-x  3       0       0       512 Aug 01 07:49 local
drwxr-xr-x  2       0       0       512 Aug 01 07:49 libexec
drwxr-xr-x 11       0       0       512 Aug 01 07:49 share
drwxr-xr-x  2       0       0       512 Aug 01 07:49 etc
drwxr-xr-x  2       0       0       512 Aug 01 07:49 sbin
-r--r--r--  2       0       0       384 May 16 2011  index.html

NOTE: The listing above will look familiar to anyone who has worked on a UNIX system. See ls.txt for an explanation of the format.

Notice that these directories are owned by "root" (UID = 0) and only root can update them. You can read the directories but you can't change them.