Good question. I've heard it many times of the years, but I can't say where. Maybe it's when the handle is not a file handle. FreeBSD's man 2 read supports this theory: "The system guarantees to read the number of bytes requested if the descriptor references a normal file that has that many bytes left before the end-of-file, but in no other case."

btw, [doc://sysread] works better than [sysread].

In reply to Re^5: Speed reading (files) by ikegami
in thread Speed reading (files) by kwaping

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