tee-like behavior in Python

[J]

On Wed, May 9, 2012 at 11:35 AM, Florian Lindner <mailinglists at xgm.de> wrote:
> Hello,
>
> how can I achieve a behavior like tee in Python?
>
> * execute an application
> * leave the output to stdout and stderr untouched
> * but capture both and save it to a file (resp. file-like object)
>
> I have this code
>
> proc = subprocess.Popen(shlex.split(cmd), stdout = subprocess.PIPE,
> stderr=subprocess.STDOUT)
> while True:
>    out = proc.stdout.readline()
>    if out == '' and proc.poll() != None:
>       break
>    sys.stdout.write(out)
>    logfile.write(out)
>
> This works so far but always buffers a couple of lines and outputs
> them en bloc. The final output is like it is desired but with a
> significant delay. Is there a way around that?

Perhaps this would help:

http://docs.python.org/library/subprocess.html#popen-constructor

specifically, the bits about setting bufsize to 0 indicating
unbuffered behaviour.