Python – Suppressing output in python subprocess call


For the following command:
            """/usr/local/itms/bin/iTMSTransporter -m lookupMetadata 
              -apple_id %s -destination %s"""%(self.apple_id, self.destination))

It prints the entire output into the Terminal window. How would I suppress ALL output here? I tried doing<command> > /dev/null 2&1)), but it didn't produce the required results. How would I do this here?

Best Solution

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

import os

devnull = open(os.devnull, 'w')
    '/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.


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