os.system question

[Fredrik Lundh]

Kevin Walzer wrote:

> I'm also skeptical of the value of subprocess, at least as a complete 
> replacement for os.popen (the original version): it currently provides 
> no way to set a 'non-blocking' mode. I make heavy use of this kind of 
> call in my code:
> 
> self.file = os.popen('do stuff here'), 'r', os.O_NONBLOCK)

Eh, what?  The third argument to os.popen is the buffer size to use for 
the file object, while O_NONBLOCK is an integer flag that you can use 
with os.open (no "p" in there), fcntl, etc. to work with fifos and 
special devices.

(O_NONBLOCK happens to be 2048 on at least some Unix machines, so 
chances are that your snippet simply opens the stream with a 2k buffer 
instead of the 4k default.)

To control the buffer size for subprocess, use the bufsize argument to 
Popen.

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