python, subprocess: reading output from subprocess

Question

I have following script:

#!/usr/bin/python

while True:
    x = raw_input()
    print x[::-1]

I am calling it from ipython:

Answer 1

Use communicate() instead of .stdout.read().

Example:

from subprocess import Popen, PIPE
p = Popen('./script.py', stdin=PIPE, stdout=PIPE, stderr=PIPE)
input = 'abc\n'
stdout, stderr = p.communicate(input)

This recommendation comes from the Popen objects section in the subprocess documentation:

Warning: Use communicate() rather than .stdin.write, .stdout.read or .stderr.read to avoid deadlocks due to any of the other OS pipe buffers filling up and blocking the child process.