How to call VBScript from python script

In the diverse world of scripting and automation, you might find yourself in a situation where a piece of legacy code or a specific Windows-specific task is perfectly handled by a VBScript (.vbs) file. But your main project is written in Python. The good news is that you don't have to choose one over the other. Python can seamlessly execute VBScript, allowing you to leverage the strengths of both languages within a single workflow.

This guide will walk you through the most popular and straightforward methods to call your VBScript files from a Python script, ensuring your automation tasks are both powerful and efficient.

The Most Popular Method: Using the `subprocess` Module

The go-to module for running external programs, including scripts, from within Python is the built-in subprocess module. It's designed to replace older modules like os.system and gives you extensive control over the execution process.

On a Windows system, VBScript files are executed by the Windows Script Host (WSH) engine, typically using the wscript.exe or cscript.exe executables. We will use subprocess to call one of these executables and pass your .vbs file as an argument.

Step-by-Step Implementation

Let's break down the process of using subprocess.run(), the recommended function for most tasks.

1. Basic Execution: This method runs the VBScript and waits for it to finish before your Python code continues.

import subprocess

# Path to your VBScript file
vbs_script_path = "C:/MyScripts/MyScript.vbs"

# Using the 'wscript' executable to run the script (shows UI if any)
result = subprocess.run(['wscript', vbs_script_path], capture_output=True, text=True)

# Print the return code (0 usually means success)
print("Return code:", result.returncode)

# Print the output (if any) from the VBScript
print("STDOUT:", result.stdout)
# Print any error messages
print("STDERR:", result.stderr)

2. Using 'cscript' for Console Output: The cscript.exe version is preferred when your VBScript uses WScript.Echo to output text, as it prints to the console (stdout) instead of a message box. This makes capturing the output in Python much easier.

import subprocess

vbs_script_path = "C:/MyScripts/MyScript.vbs"

# Using 'cscript' to run the script and capture its console output
result = subprocess.run(['cscript', '//Nologo', vbs_script_path], capture_output=True, text=True)

# The '//Nologo' flag suppresses the Microsoft copyright banner from the output

print("Return code:", result.returncode)
print("Script output:", result.stdout)

Handling Errors and Return Codes

It's crucial to check if the VBScript ran successfully. The returncode attribute of the result object helps with this. A return code of 0 typically indicates success, while a non-zero value suggests an error occurred. You can build logic around this.

if result.returncode == 0:
    print("VBScript executed successfully!")
    print("Output:", result.stdout)
else:
    print("VBScript failed with error code:", result.returncode)
    print("Error message:", result.stderr)

Passing Arguments to Your VBScript

Often, you need to make your VBScript dynamic by passing arguments from your Python script. This is simple with subprocess.

In Python: You simply add the arguments to the list after the script path.

arg1 = "Hello"
arg2 = "World"
result = subprocess.run(['cscript', '//Nologo', vbs_script_path, arg1, arg2], capture_output=True, text=True)

In VBScript (MyScript.vbs): You access the arguments using the `WScript.Arguments` collection.

' MyScript.vbs
Set args = WScript.Arguments
firstArg = args(0) ' This will be "Hello"
secondArg = args(1) ' This will be "World"

WScript.Echo "Arguments received: " & firstArg & " and " & secondArg

Alternative Method: Using `os.system()`

While subprocess is the modern standard, the older os.system() function can be used for quick, simple tasks. However, it offers less control and does not easily capture output.

import os

return_code = os.system('cscript //Nologo "C:/MyScripts/MyScript.vbs"')
# Note: The return code is a 16-bit value containing different information than subprocess.

For any serious automation, subprocess.run() is highly recommended over os.system().

Best Practices and Considerations

Use Raw Strings or Double Backslashes for Paths: To avoid issues with Python interpreting backslashes as escape characters, use raw strings (r"C:\path\to\script.vbs") or double backslashes ("C:\\path\\to\\script.vbs").
Error Handling: Always wrap your subprocess calls in try...except blocks to handle potential exceptions, like the file not being found (FileNotFoundError).
Security: Be cautious if the arguments you are passing come from user input, as this could be a vector for command injection attacks. Sanitise your inputs.
Blocking vs. Non-blocking: subprocess.run() is blocking. If you need to run the VBScript asynchronously (without waiting for it to finish), you would need to look into subprocess.Popen().

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