Help with nobuffered I/O in 4.1

[gwyn at BRL-TGR.ARPA]

From:      Doug Gwyn <gwyn at BRL-TGR.ARPA>

The correct use of a file descriptor obtained from open(2) is to
use it as a parameter in read(2) and write(2) calls, finally close(2).
read(2) and write(2) are as unbuffered as you are going to get without
using a non-filesystem "raw disk" device (the only buffering is inside
the kernel and cannot be bypassed).

Really, this question belonged on info-unix rather than unix-wizards.