How to get both return code and output from subprocess in Python? [duplicate]

Question

While developing python wrapper library for Android Debug Bridge (ADB), I'm using subprocess to execute adb commands in shell. Here is the simplified example:

import subprocess

...

def exec_adb_command(adb_command):
    return = subprocess.call(adb_command)

If command executed propery exec_adb_command returns 0 which is OK.

But some adb commands return not only "0" or "1" but also generate some output which I want to catch also. adb devices for example:

D:\git\adb-lib\test>adb devices
List of devices attached
07eeb4bb        device

I've already tried subprocess.check_output() for that purpose, and it does return output but not the return code ("0" or "1").

Ideally I would want to get a tuple where t[0] is return code and t[1] is actual output.

Am I missing something in subprocess module which already allows to get such kind of results?

Thanks!

Padraic Cunningham · Accepted Answer · 2015-06-19 14:51:17Z

43

Popen and communicate will allow you to get the output and the return code.

from subprocess import Popen,PIPE,STDOUT

out = Popen(["adb", "devices"],stderr=STDOUT,stdout=PIPE)

t = out.communicate()[0],out.returncode
print(t)
('List of devices attached \n\n', 0)

check_output may also be suitable, a non-zero exit status will raise a CalledProcessError:

from subprocess import check_output, CalledProcessError

try:
    out = check_output(["adb", "devices"])
    t = 0, out
except CalledProcessError as e:
    t = e.returncode, e.message

You also need to redirect stderr to store the error output:

from subprocess import check_output, CalledProcessError

from tempfile import TemporaryFile

def get_out(*args):
    with TemporaryFile() as t:
        try:
            out = check_output(args, stderr=t)
            return  0, out
        except CalledProcessError as e:
            t.seek(0)
            return e.returncode, t.read()

Just pass your commands:

In [5]: get_out("adb","devices")
Out[5]: (0, 'List of devices attached \n\n')

In [6]: get_out("adb","devices","foo")
Out[6]: (1, 'Usage: adb devices [-l]\n')

edited Jun 19, 2015 at 14:51

answered Jun 19, 2015 at 12:14

Padraic Cunningham

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4 Comments

Viktor Malyi Over a year ago

Thank you for the broad answer!

Padraic Cunningham Over a year ago

@ViktorMalyi, no prob, you're welcome.

Leedehai Over a year ago

It should not be e.message, but e.output: python2 doc, python3 doc?

Noam Manos Over a year ago

In Python 2: rc, out = commands.getstatusoutput("cmd..."), In Python 3: rc, out = subprocess.getstatusoutput("cmd...")

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