shlex and subprocess Popen in python to execute external command and get return code plus result.

extern.py

#!/usr/bin/python
import subprocess, sys, shlex

def main(argv):
  args = shlex.split(argv)
  op = subprocess.Popen(args,stdout=subprocess.PIPE)
  result, err =  op.communicate()
  op.wait()
  tw = op.returncode
  # Use the result , error and return code here for extra processing

if __name__ == "__main__":
  main(sys.argv[1])