Suppressing output in python subprocess call

Question

(This question already has answers here): question from:https://stackoverflow.com/questions/10251391/suppressing-output-in-python-subprocess-call

Answer 1

You can use the stdout= and stderr= parameters to subprocess.call() to direct stdout or stderr to a file descriptor of your choice. So maybe something like this:

import os

devnull = open(os.devnull, 'w')
subprocess.call(shlex.split(
    '/usr/local/itms/bin/iTMSTransporter -m lookupMetadata '
    '-apple_id %s -destination %s' % (self,apple_id, self.destination)),
  stdout=devnull, stderr=devnull)

Using subprocess.PIPE, if you're not reading from the pipe, could cause your program to block if it generates a lot of output.

Update

As @yanlend mentions in a comment, newer (3.x) versions of Python include subprocess.DEVNULL to solve this problem in a more convenient and portable fashion. In that case, the code would look like:

subprocess.call(shlex.split(
    '/usr/local/itms/bin/iTMSTransporter -m lookupMetadata '
    '-apple_id %s -destination %s' % (self,apple_id, self.destination)),
  stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL)