disk_free_space
    (PHP 4 >= 4.1.0)
disk_free_space -- Returns available space in directory
Description
float 
disk_free_space ( string directory)
     Given a string containing a directory, this function will return
     the number of bytes available on the corresponding filesystem or
     disk partition.
    
     
Example 1. disk_free_space() example $df = disk_free_space("/"); // $df contains the number of bytes 
                            // available on "/" |  
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