Running an outside program (executable) in Python?

Question

I just started working on Python, and I have been trying to run an outside executable from Python.

I have an executable for a program written in Fortran. Let’s say the name for the executable is flow.exe. And my executable is located in C:Documents and Settingsflow_model. I tried both os.system and popen commands, but so far I couldn't make it work. The following code seems like it opens the command window, but it wouldn't execute the model.

# Import system modules
import sys, string, os, arcgisscripting
os.system("C:/Documents and Settings/flow_model/flow.exe")

How can I fix this?

Answer 1

If using Python 2.7 or higher (especially prior to Python 3.5) you can use the following:

import subprocess

• subprocess.call(args, *, stdin=None, stdout=None, stderr=None, shell=False) Runs the command described by args. Waits for command to complete, then returns the returncode attribute.
• subprocess.check_call(args, *, stdin=None, stdout=None, stderr=None, shell=False) Runs command with arguments. Waits for command to complete. If the return code was zero then returns, otherwise raises CalledProcessError. The CalledProcessError object will have the return code in the returncode attribute

Example: subprocess.check_call([r"C:pathToYourProgramyourProgram.exe", "your", "arguments", "comma", "separated"])

In regular Python strings, the U character combination signals a extended Unicode code point escape.

Here is the link to the documentation: http://docs.python.org/3.2/library/subprocess.html

For Python 3.5+ you can now use run() in many cases: https://docs.python.org/3.5/library/subprocess.html#subprocess.run