From mboxrd@z Thu Jan  1 00:00:00 1970
Message-ID: <84ee8e0fc6f0318c80b7e464cbde5c95@plan9.bell-labs.com>
From: "Russ Cox" <rsc@plan9.bell-labs.com>
To: 9fans@cse.psu.edu
Subject: Re: [9fans] bidirectional pipes
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Date: Thu,  2 May 2002 18:30:29 -0400
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> | I'm curious?  Why does this bother you?  Just let half the connection
> | go unused.
>
> I think that having two open fds is nicer than one open fd and some extra
> system calls, because it's impossible to get it wrong.  Plan 9 doesn't
> have a way to do half-close at all, right?  So what if your server was
> "sort" instead of "ssh"?

Then you can set it up with a different pipe for
input and for output, and then close the input pipe.
Problem solved.  This is what rc does by default.
The <[0=1] explicitly worked around this.

If you'd rather have one fd and don't need the half-open
nonsense, you can use the same pipe for both.

The only real difference is that if you try to write to
a pipe that it only makes sense to read from, you won't
notice when the pipe is bidirectional.

Russ