Python function that runs a shell command and returns output as string.

cmd.py

from subprocess import Popen, PIPE

def cmd(*args):
    """Runs a shell command and returns the output as a string."""
    out, err = Popen(args, stdout=PIPE, stderr=PIPE).communicate()

    # Convert output from byte array to string.
    out = out.decode('utf-8')
    err = err.decode('utf-8')

    if err:
        raise Exception(err)

    return out