Direct I/O functions
PHP supports the direct io functions as described in the
Posix Standard (Section 6) for performing I/O functions at
a lower level than the C-Language stream I/O functions
DIO provides functions and stream wrappers which provide raw and
serial low level IO support. The use of the DIO functions should
be considered only when direct control of a device is needed.
In all other cases, the standard filesystem functions are
more than adequate.