Mail Archives: cygwin/2003/04/03/19:46:42
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
Steven Kilby
Lead, Programmer Analyst
Vision Solutions, Inc.
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-----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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