Run PowerShell function from Python script


Question

I have a need to run a PowerShell function from a Python script. Both the .ps1 and the .py files currently live in the same directory. The functions I want to call are in the PowerShell script. Most answers I've seen are for running entire PowerShell scripts from Python. In this case, I'm trying to run an individual function within a PowerShell script from a Python script.

Here is the sample PowerShell script:

# sample PowerShell
Function hello
{
    Write-Host "Hi from the hello function : )"
}

Function bye
{
    Write-Host "Goodbye"
}

Write-Host "PowerShell sample says hello."

and the Python script:

import argparse
import subprocess as sp

parser = argparse.ArgumentParser(description='Sample call to PowerShell function from Python')
parser.add_argument('--functionToCall', metavar='-f', default='hello', help='Specify function to run')

args = parser.parse_args()

psResult = sp.Popen([r'C:\WINDOWS\system32\WindowsPowerShell\v1.0\powershell.exe',
'-ExecutionPolicy',
'Unrestricted',
'. ./samplePowerShell',
args.functionToCall],
stdout = sp.PIPE,
stderr = sp.PIPE)

output, error = psResult.communicate()
rc = psResult.returncode

print "Return code given to Python script is: " + str(rc)
print "\n\nstdout:\n\n" + str(output)
print "\n\nstderr: " + str(error)

So, somehow, I want to run the 'hello()' or the 'bye()' function that is in the PowerShell sample. It would also be nice to know how to pass in parameters to the function. Thanks!

1
25
1/24/2013 7:05:02 PM

You want two things: dot source the script (which is (as far as I know) similar to python's import), and subprocess.call.

import subprocess
subprocess.call(["C:\\WINDOWS\\system32\\WindowsPowerShell\\v1.0\\powershell.exe", ". \"./SamplePowershell\";", "&hello"])

so what happens here is that we start up powershell, tell it to import your script, and use a semicolon to end that statement. Then we can execute more commands, namely, hello.

You also want to add parameters to the functions, so let's use the one from the article above (modified slightly):

Function addOne($intIN)
{
    Write-Host ($intIN + 1)
}

and then call the function with whatever parameter you want, as long as powershell can handle that input. So we'll modify the above python to:

import subprocess
subprocess.call(["C:\\WINDOWS\\system32\\WindowsPowerShell\\v1.0\\powershell.exe", ". \"./SamplePowershell\";", "&addOne(10)"])

this gives me the output:

PowerShell sample says hello.
11
35
1/28/2013 2:32:01 AM

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