Mail Archives: cygwin/2003/04/03/20:04:00
Randall,
Good call. As soon as I started to post the source I realized that I
had placed the call to fflush after the sleep. And you were right about
cygwin emacs, it is using pty's.
Thanks
Steven
(sorry - signature is forced on me by company)
Steven Kilby
Lead, Programmer Analyst
Vision Solutions, Inc.
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Disclaimer - 4/3/2003
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-----Original Message-----
From: Randall R Schulz [mailto:rrschulz AT cris DOT com]
Sent: Thursday, April 03, 2003 4:54 PM
To: cygwin AT cygwin DOT com
Subject: RE: Pipe behavior
Steven,
I assume the test program you're using to explore this behavior is
pretty concise. Why don't you post it here?
Randall Schulz
At 16:44 2003-04-03, Steven Kilby wrote:
>Randall,
>
>Thanks for the response. No, I am not sure that Emacs uses pipes
>instead of ptys. I'll have to look at that. I was testing with the
>cygwin character emacs. What you said makes sense but I have one more
>question. I modified the code by inserting a call to fflush between
>the printf's. I would have thought this would force the first printf
>to display immediately but this did not happen. Can you help me
>understand why?
>
>Thanks
>
>Steven
>
>>Original Message-----
>>From: Randall R Schulz [mailto:rrschulz AT cris DOT com]
>>Sent: Thursday, April 03, 2003 4:41 PM
>>To: cygwin AT cygwin DOT com
>>Subject: Re: Pipe behavior
>>
>>
>>Steven,
>>
>>At 16:28 2003-04-03, you wrote:
>> >Hello,
>> >
>> >I have a question about pipe behavior. I wrote a simple program
>> >that does a printf, sleeps for 5 seconds and then another printf.
>> >If I run the program with the following way: $ ./simple | cat The
>> >output is delayed until the program finished. I guessed that the
>> >pipe is buffered and doesn't flush until it is closed when the
>> >program ends. But then I ran the same program as an emacs subprocess
>> >and attached a buffer to it. In this scenario the first printf is
>> >displayed, 5 seconds
>>
>> >pass and then the second printf is displayed. Emacs also uses pipes
>> >so
>>
>> >I do not understand why the behavior is different.
>>
>>Pipes don't buffer in the manner you describe, but the standard I/O
>>library does when its output is directed to a pipe or a plain file.
>>
>>Are you sure that Emacs uses pipes and not ptys (pseudo-ttys)?
>>
>>Which Emacs are you using? Cygwin or Windows?
>>
>>
>> >Thanks
>> >Steven Kilby
>>
>>
>>Randall "We don't need no stinkin' disclaimers" Schulz
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