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Path: utzoo!linus!security!genrad!grkermit!masscomp!clyde!floyd!harpo!seismo!hao!hplabs!sri-unix!cepu!scw@ucla-locus
From: scw%ucla-locus@cepu.UUCP
Newsgroups: net.unix
Subject: re:pipes
Message-ID: <14542@sri-arpa.UUCP>
Date: Mon, 12-Dec-83 14:57:00 EST
Article-I.D.: sri-arpa.14542
Posted: Mon Dec 12 14:57:00 1983
Date-Received: Thu, 15-Dec-83 01:55:56 EST
Lines: 15

From:  Steve Woods <cepu!scw@ucla-locus>

This question is more in the relm of info-unix

	Concerning ANY REAL, i.e. bsd or bell, unix systems.

	I have several processes all writing to the same pipe at once.  If in
	those processes I say:
		write(p[1], buf, 100);
	can I depend on all 100 bytes being together, even if somebody else
	decides to write at or about the same time?

According to pipe(2) 'Writes with a count of 4096 or less bytes are atomic;
no other process can intersperse data'. The answer is yes, your write of 100
bytes will all be in one packet.