Is write(2) "atomic" ?

[Chuck Karish]

in article <11410005 at eecs.nwu.edu> naim at eecs.nwu.edu (Naim Abdullah) writes:
> Do UNIX semantics guarantee that write(2) calls will be "atomic" ?

	If the write() is to a pipe or to a FIFO, and the request is for
	[PIPE_BUF] bytes or fewer, the write() is guaranteed to be
	atomic by the SVID and by the POSIX 1003.1 draft standard.
	For other write()s, the behavior is undefined; you take your
	chances.  If you absolutely, positively need atomic write()s,
	cram your I/O through a pipe or set up your own locking scheme.

Chuck Karish	ARPA:	karish at denali.stanford.edu
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