How to store output from a bash command?

Question

I need to write a simple python (python3) script to store my local Ip address in a variable in order to manipulate it later, I read a lot around but I don't understand where I'm doing wrong here a chunk of code for a better understanding..

#!/usr/bin/env pyhton3
import os
import subprocess
import sys
import fileinput
localip = subprocess.call(["ifconfig | grep 'inet addr' | cut -d ':' -f2 | grep 'Bcast' | cut -d ' ' -f1"], shell=True)
print localip
...
...
...

now when I excecute it it prints me this:

pi@raspberrypi:~/Documents $ python change.py
192.168.1.6
0

It seems I can't find a solution to this on my own, can anyone tell me where I'm doing wrong and help me out? thanks.

As explained in the documentation, the value returned by subprocess.call is the command's return code, which is used to indicate whether the command succeeded. In this case it is zero, because there was no error. — kindall
– kindall, Commented Mar 18, 2016 at 17:00
Don't go out to the shell to get info about your network interface. I don't know if this is the canonical solution, but it took all of 10 seconds to find pypi.python.org/pypi/netifaces — William Pursell
– William Pursell, Commented Mar 18, 2016 at 17:08

Community · Accepted Answer · 2017-03-20 10:29:34Z

2

To address your XY Problem, why not just use Python itself to get your IP / hostname?

>>> import socket
>>> socket.gethostname()
'MY-COMPUTER'
>>> socket.gethostbyname(socket.gethostname())
'192.168.1.126'
>>> socket.getfqdn()
'my-computer.local'
>>> socket.gethostbyname(socket.getfqdn())
'192.168.1.126'

edited Mar 20, 2017 at 10:29

CommunityBot

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answered Mar 18, 2016 at 17:06

OneCricketeer

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Comments

SpoonMeiser · Accepted Answer · 2016-03-18 17:01:48Z

1

In python2, you'd do:

stdout = subprocess.check_output(args, shell=true)

In python3, you can also do:

completed_process = subprocess.run(args, shell=True)
stdout = completed_process.stdout

Which might be a more useful interface

edited Mar 18, 2016 at 17:01

answered Mar 18, 2016 at 16:56

SpoonMeiser

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