Description
int 
filegroup ( string filename )
    
     Returns the group ID of the file, or FALSE in case
     of an error. The group ID is returned in numerical format, use
     posix_getgrgid() to resolve it to a group name.
     Upon failure, FALSE is returned along with an error of level
     E_WARNING.
    
Note: The results of this 
function are cached. See clearstatcache() for 
more details.
Tip: As of PHP 5.0.0 this function
can also be used with some URL wrappers.  Refer to 
Appendix M for a listing of which wrappers support 
stat() family of functionality.
     See also fileowner(), and
     safe_mode_gid.