Running powershell script within python script, how to make python print the powershell output while it is running

1. Make sure you can run powershell scripts (it is disabled by default). Likely you have already done this. http://technet.microsoft.com/en-us/library/ee176949.aspx

   Set-ExecutionPolicy RemoteSigned
   

2. Run this python script on your powershell script helloworld.py:

   # -*- coding: iso-8859-1 -*-
   import subprocess, sys
   
   p = subprocess.Popen(["powershell.exe", 
                 "C:\\Users\\USER\\Desktop\\helloworld.ps1"], 
                 stdout=sys.stdout)
   p.communicate()
   

This code is based on python3.4 (or any 3.x series interpreter), though it should work on python2.x series as well.

C:\Users\MacEwin\Desktop>python helloworld.py
Hello World

I don't have Python 2.7 installed, but in Python 3.3 calling Popen with stdout set to sys.stdout worked just fine. Not before I had escaped the backslashes in the path, though.

>>> import subprocess
>>> import sys
>>> p = subprocess.Popen(['powershell.exe', 'C:\\Temp\\test.ps1'], stdout=sys.stdout)
>>> Hello World
_

In addition to the previous answers, I have some suggestions which makes your code more portable.

Instead of setting ExecutionPolicy globally to RemoteSigned (which imposes some security issues) you can use this to set it only for the PowerShell instance created by your Python script:

import subprocess, sys    
p = subprocess.Popen('powershell.exe -ExecutionPolicy RemoteSigned -file "hello world.ps1"', stdout=sys.stdout)
p.communicate()

Note the quotes which allows your PowerShell-script's path/filename to contain spaces.

Furthermore, as shown in the above example, you can use a relative path to call your PowerShell script. The path is relative to your Python workspace directory.