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The Windows Python Launcher provides multiple methods for running Python scripts, making it flexible for different workflows and use cases.

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Running Methods

There are three primary ways to run Python scripts with the launcher:

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1. Double-Click Execution

The simplest method is to double-click the PythonLauncher.bat file. The launcher will automatically:
1

Check for Python installation

Verify that Python is installed on your system
2

Create virtual environment (if enabled)

Set up a virtual environment based on the usevenv configuration
3

Install dependencies

Install packages from requirements.txt if configured
4

Auto-detect and run initial file

Search for and execute the first matching initial file from the configured list
By default, the launcher looks for these files in order: run.py, main.py, app.py. It will run the first one it finds.
Example scenario: 
# Your project structure
my-project/
├── PythonLauncher.bat
├── main.py
├── requirements.txt
└── pyvenv/  (created automatically)
When you double-click PythonLauncher.bat, it will:
  • Create the pyvenv virtual environment (first run only)
  • Install dependencies from requirements.txt (first run only)
  • Run main.py

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2. Drag and Drop Execution

You can drag and drop any Python file onto the launcher to run it directly.
Drag and drop only works when passarguments=0 in the configuration. If passarguments=1, drag and drop is disabled to allow command-line argument passing.
How it works:
1

Drag a Python file

Select any .py file and drag it onto PythonLauncher.bat
2

Launcher receives file path

The batch script receives the file path as the first argument
3

Script executes

The launcher runs the specified file in the configured environment
Command prompt example: 
C:\Projects\my-app> start "Python" cmd /k "pyvenv\Scripts\activate & py -3.11 utils\helper.py"
See Drag and Drop for more details.

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3. Command Line with Arguments

When passarguments=1, you can run the launcher from the command line with arguments that will be passed to your Python script. Configuration: 
set passarguments=1
Usage: 
PythonLauncher.bat --debug --config=production
This will:
  1. Find and run the first matching initial file (e.g., run.py)
  2. Pass --debug --config=production to the Python script
Example Python script receiving arguments: 
import sys

print(f"Arguments received: {sys.argv[1:]}")
# Output: Arguments received: ['--debug', '--config=production']
See Arguments for more details.

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Execution Behavior

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Window Management

The launcher provides options to control the command prompt window: Minimized Execution: 
set minimizedcmd=1  # Starts command prompt minimized
Auto-Close: 
set autoclosecmd=1  # Closes window when script finishes
Combine minimizedcmd=1 and autoclosecmd=1 for background script execution that doesn’t leave windows open.
Custom Window Title: 
set windowname=My Python App
The command prompt window will display “My Python App” in the title bar.

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No Initial File Found

If no initial file is found, the launcher will:
  • Open a Python interactive shell (REPL) if passarguments=0
  • Open a Python interactive shell in the configured environment if passarguments=1 but no initial files exist
Example output: 
C:\Projects\test> py -3.11
Python 3.11.5 (tags/v3.11.5:...) on win32
Type "help", "copyright", "credits" or "license" for more information.
>>>

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Virtual Environment Integration

When running scripts, the launcher automatically:
  1. Activates the virtual environment (if usevenv=1)
  2. Runs your script within that environment
  3. Keeps the window open for you to see output (unless autoclosecmd=1)
Actual command executed: 
cmd /k "pyvenv\Scripts\activate & py -3.11 main.py"
The /k flag keeps the command prompt open after execution, allowing you to see errors and output.

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Python Version Selection

The launcher respects your Python version configuration: 
set pythonversion=3.11
set pythondir=py
This uses the Windows Python Launcher (py) with the -3.11 flag to target Python 3.11 specifically. Alternative - Portable Python: 
set pythondir=%cd%\python\python.exe
This uses a portable Python installation in your project directory.

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Quick Reference

MethodCommandRequirements
Double-clickRun PythonLauncher.batInitial file must exist
Drag and dropDrag .py file onto launcherpassarguments=0
With argumentsPythonLauncher.bat --arg1 --arg2passarguments=1
Direct filePythonLauncher.bat script.pypassarguments=0
The launcher always checks for Python installation first. If Python is not found and alertifpynotinstalled=1, it will open the Python download page.