Python: How do I redirect this output?

Question

I\'m calling rtmpdump via subprocess and trying to redirect its output to a file. The problem is that I simply can\'t redirect it.

I tried first setting up the sys.s

Answer 1

sys.stdout is the python's idea of the parent's output stream.

In any case you want to change the child's output stream.

subprocess.call and subprocess.Popen take named parameters for the output streams.

So open the file you want to output to and then pass that as the appropriate argument to subprocess.

f = open("outputFile","wb")
subprocess.call(argsArray,stdout=f)

Your talk of using >> suggest you are using shell=True, or think you are passing your arguments to the shell. In any case it is better to use the array form of subprocess, which avoid an unnecessary process, and any weirdness from the shell.

EDIT:

So I downloaded RTMPDump and tried it out, it would appear the messages are appearing on stderr.

So with the following program, nothing appears on the programs output, and the rtmpdump logs when into the stderr.txt file:

#!/usr/bin/env python

import os
import subprocess

RTMPDUMP="./rtmpdump"
assert os.path.isfile(RTMPDUMP)
command = [RTMPDUMP,'-r','rtmp://oxy.videolectures.net/video/',
        '-y','2007/pascal/bootcamp07_vilanova/keller_mikaela/bootcamp07_keller_bss_01',
        '-a','video','-s',
        'http://media.videolectures.net/jw-player/player.swf',
        '-w','ffa4f0c469cfbe1f449ec42462e8c3ba16600f5a4b311980bb626893ca81f388'
        ,'-x','53910','-o','test.flv']


stdout = open("stdout.txt","wb")
stderr = open("stderr.txt","wb")
subprocess.call(command,stdout=stdout,stderr=stderr)

Answer 2

See the link on getting the output from subprocess on SO

• Getting the entire output from subprocess.Popen
• https://stackoverflow.com/questions/tagged/subprocess

I guess the way would be to collect the output and write it to a file directly or provide file descriptors to which you output can be written.

Something like this:

f = open('dump.txt', 'wb')
p = subprocess.Popen(args, stdout=f, stderr=subprocess.STDOUT, shell=True)