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up vote 3 down vote favorite

I am retrieving information about my wireless connection by using

In [4]: subprocess.check_output('iwconfig')
eth0      no wireless extensions.

lo        no wireless extensions.

Out[4]: 'wlan0 ...'

I get the string that I want, but I would like to clean the shell from the information about eth0 and lo (notice that these lines are not in the check_ouput return string, they are printed to the shell between ipython's In [4] and Out [4]).

My current guess is that these two lines are considered a warning and are not caught by check_output. Hoping they output to stderr I tried a few variations on

iwconfig > /dev/null 2>&1  # empties my wanted string
iwconfig 2 > /dev/null     # throws an error

but without success so far.

How can I prevent the check_output from outputting anything to the shell?

share|improve this question
up vote 3 down vote accepted

If you want the stderr as your stdout:

subprocess.check_output('iwconfig', stderr=subprocess.STDOUT)

If what you want is just to wipe out your stderr:

import os
subprocess.check_output('iwconfig', stderr=open(os.devnull, 'w'))
share|improve this answer
    
Awesome, thank you ! – user60177 Oct 9 '14 at 15:41

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