Attempts to change the owner of the file
user (specified by name or number). Only
the superuser may change the owner of a file.
Returns TRUE on success or FALSE on failure.
Note: This function will not work on remote files as the file to be examined must be accessible via the servers filesystem.
Note: When safe mode is enabled, PHP checks whether the files or directories you are about to operate on have the same UID (owner) as the script that is being executed.
See also chmod().