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Subject: Re: How to send EOF to the popen(3) pipe?
To: "Montgomery-Smith, Stephen" <stephen@missouri.edu>,
 "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org>
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From: Yuri <yuri@rawbw.com>
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Date: Sat, 16 Jan 2016 09:59:36 -0800
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On 01/15/2016 20:35, Montgomery-Smith, Stephen wrote:
> Maybe I am displaying my ignorance.  But wouldn't you do this by
> invoking the function pclose?

No, pclose kills the process and returns the exit code. Half-closed 
connection though can be alive for a while, until the other side 
finishes and closes the pipe.

> My memory of using this was that this could gridlock because of
> buffering.  Suppose process A popens a process B.  A sends a message to

Gridlocks are possible if reads/writes are performed in the wrong order. 
But this is besides the point of the original question.

I think the answer to my question is "no". popen(3) can't send EOF. 
Protocol needs to support EOF signal on the application-level.

Yuri