Iterating through 2 files simultaneously

[glman74]

Hi folks,

I am trying to tee off both stdout and stderr from a process run
through Popen.
As a test, I am first trying to print the output below:

from subprocess import Popen,PIPE
....
p1 = Popen(['cvs', 'update'], stdout=PIPE, stderr=PIPE)
for (l1, l2) in zip(p1.stdout, p1.stderr):
print '-->' + l1,
print '-->' + l2,

This doesn't work - probably because I cannot iterate through the
pipes this way.

I am new to Python, and I'd appreciate it if you could please explain
why this
doesn't work and/or suggest an alternate way to redirect stdout and
stderr to a
common place.

My objective is for my code to print out stdout/stderr messages and at
the same
time redirect them to a log file.

Thanks

Mahesh

[Rob Williscroft]

wrote in news:7ae96aff-c1a7-4763-8db7-
ff**********@u6g2000prc.googlegroups.com in comp.lang.python:

Hi folks,

I am trying to tee off both stdout and stderr from a process run
through Popen.
As a test, I am first trying to print the output below:

from subprocess import Popen,PIPE
...
p1 = Popen(['cvs', 'update'], stdout=PIPE, stderr=PIPE)
for (l1, l2) in zip(p1.stdout, p1.stderr):
print '-->' + l1,
print '-->' + l2,

This doesn't work - probably because I cannot iterate through the
pipes this way.

I am new to Python, and I'd appreciate it if you could please explain
why this
doesn't work and/or suggest an alternate way to redirect stdout and
stderr to a
common place.

My objective is for my code to print out stdout/stderr messages and at
the same
time redirect them to a log file.

From the manual <url: http://docs.python.org/lib/node528.html>:

stdin, stdout and stderr specify ...
.... Additionally, stderr can be STDOUT, which indicates that the stderr
data from the applications should be captured into the same file handle
as for stdout.

So import STDOUT and make stderr=STDOUT in the Popen call, you will then
have one file/pipe to deal with p1.stdout.

Rob.
--
http://www.victim-prime.dsl.pipex.com/

[glman74]

>

So import STDOUT and make stderr=STDOUT in the Popen call, you will then
have one file/pipe to deal with p1.stdout.

Thank you - that works great!

Mahesh