From owner-freebsd-hackers Sun May 11 10:24:02 1997 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.5/8.8.5) id KAA05402 for hackers-outgoing; Sun, 11 May 1997 10:24:02 -0700 (PDT) Received: from punt-1.mail.demon.net (relay-7.mail.demon.net [194.217.242.9]) by hub.freebsd.org (8.8.5/8.8.5) with SMTP id KAA05364 for ; Sun, 11 May 1997 10:23:57 -0700 (PDT) Received: from erlenstar.demon.co.uk ([194.222.144.22]) by punt-1.mail.demon.net id aa0604400; 11 May 97 17:55 BST Received: (from andrew@localhost) by erlenstar.demon.co.uk (8.8.5/8.8.5) id RAA16330; Sun, 11 May 1997 17:54:37 +0100 (BST) To: "John S. Dyson" Cc: freebsd-hackers@freebsd.org Subject: Re: socketpair() References: <199705111555.KAA08056@dyson.iquest.net> From: Andrew Gierth In-Reply-To: "John S. Dyson"'s message of Sun, 11 May 1997 10:55:47 -0500 (EST) X-Mayan-Date: Long count = 12.19.4.2.15; tzolkin = 6 Men; haab = 13 Uo X-Attribution: AG Date: 11 May 1997 17:54:37 +0100 Message-ID: <87rafene42.fsf@erlenstar.demon.co.uk> Lines: 26 X-Mailer: Gnus v5.3/Emacs 19.34 Sender: owner-hackers@freebsd.org X-Loop: FreeBSD.org Precedence: bulk >>>>> "John" == John S Dyson writes: John> I wrote most of our new pipe code -- and I might be a little bit John> confused... I meant to support bidirectional pipes, and it sure John> looks like we have them (at least looking at the code.) Haven't John> tested it recently though. $ cat <&1 >&2 | echo hello >&0 hello $ Works OK on RELENG-2.2 at least. As far as I can tell, though, bidirectional pipes are still pretty much confined to SVR4 (STREAMS pipes) and FreeBSD; most of the other flavours I've encountered still use unidirectional pipes (at least by default; some, like HP-UX 10.10, have a switch for it in the kernel parameters). In other words, having support for bidirectional pipes is nice, but relying on them will probably get you into trouble. Is there actually any good reason for having bidirectional pipes, other than for coping with code ported from SVR4? -- Andrew.