Store output of subprocess.Popen call in a string [duplicate]

Question

I'm trying to make a system call in Python and store the output to a string that I can manipulate in the Python program.

#!/usr/bin/python import subprocess p2 = subprocess.Popen("ntpq -p") 

I've tried a few things including some of the suggestions here:

Retrieving the output of subprocess.call()

but without any luck.

Answer 1

In Python 2.7 or Python 3

Instead of making a Popen object directly, you can use the subprocess.check_output() function to store output of a command in a string:

from subprocess import check_output out = check_output(["ntpq", "-p"]) 

In Python 2.4-2.6

Use the communicate method.

import subprocess p = subprocess.Popen(["ntpq", "-p"], stdout=subprocess.PIPE) out, err = p.communicate() 

out is what you want.

Important note about the other answers

Note how I passed in the command. The "ntpq -p" example brings up another matter. Since Popen does not invoke the shell, you would use a list of the command and options—["ntpq", "-p"].

Answer 2

This worked for me for redirecting stdout (stderr can be handled similarly):

from subprocess import Popen, PIPE pipe = Popen(path, stdout=PIPE) text = pipe.communicate()[0] 

If it doesn't work for you, please specify exactly the problem you're having.