Why does bufsize=1 not work in subprocess.Popen ?

[I. Myself]

I read in the docs that "bufsize=1" causes line buffering. (for
subprocess.Popen)

The following tiny program launches an executable file and then receives
its output. That works, but I want to
receive each line as it is ouput, not all of the lines at termination,
which is what is happening.
-------------------------------------------------------
from subprocess import Popen, PIPE
from os import remove, sep

p = Popen("." + sep + "myprogram", stdout=PIPE, bufsize=1)

while(1):
line = p.stdout.readline() # get next line
print line,
if line.count("terminator"):
break
------------------------------------------------------
How can I get line buffering?

Mitchell Timin

--
I'm proud of http://ANNEvolve.sourceforge.net. If you want to write software,
or articles, or do testing or research for ANNEvolve, let me know.

Humans may know that my email address is: (but remove the 3 digit number)
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[Marc 'BlackJack' Rintsch]

In <V6R4g.89900$P01.79112@pd7tw3no>, I. Myself wrote:

I read in the docs that "bufsize=1" causes line buffering. (for
subprocess.Popen)

The following tiny program launches an executable file and then receives
its output. That works, but I want to
receive each line as it is ouput, not all of the lines at termination,
which is what is happening.

From the Python side you can only control Python's input buffer but not
the output buffer of the external program you are starting. I guess that
programs buffers its output.

Ciao,
Marc 'BlackJack' Rintsch

[I. Myself]

Marc 'BlackJack' Rintsch wrote:

In <V6R4g.89900$P01.79112@pd7tw3no>, I. Myself wrote:

I read in the docs that "bufsize=1" causes line buffering. (for
subprocess.Popen)

The following tiny program launches an executable file and then receives
its output. That works, but I want to
receive each line as it is ouput, not all of the lines at termination,
which is what is happening.

From the Python side you can only control Python's input buffer but not
the output buffer of the external program you are starting. I guess that
programs buffers its output.

Ciao,
Marc 'BlackJack' Rintsch

That makes sense. I remember now that someone told me that Windows
sends line-by-line only to the screen. To a pipe it sends buffers full.

Thanks,

Mitchell Timin

--
I'm proud of http://ANNEvolve.sourceforge.net. If you want to write software,
or articles, or do testing or research for ANNEvolve, let me know.

Humans may know that my email address is: (but remove the 3 digit number)
zenguy at shaw666 dot ca