macOS Launchd Run-As-User Starter Script

Description

This is a universal Python starter script designed for running Python code as a specified user within a specific virtual environment. It is particularly useful for macOS users who wish to integrate Python scripts with launchd.

How it Works

The script takes four or more command-line arguments:

1. username: The username under which the script should be executed.
2. venv-python-path: The path to the Python interpreter in the virtual environment.
3. python-script: The path to the Python script that should be executed.
4. [arg1, arg2, ...]: Additional arguments to pass to the Python script.

It sets up the environment for the specified user and runs the Python script within that user's context.

Usage

Run the script like so:

python starterscript.py <username> <venv-python-path> <python-script> [arg1 arg2 ...]

Example: Monitoring ~/Downloads using launchd

You can use this script to monitor a folder, such as ~/Downloads, and trigger an action when something changes. Create a .plist file under ~/Library/LaunchAgents/, for example, com.example.monitorDownloads.plist:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>Label</key>
  <string>com.example.monitorDownloads</string>

  <key>ProgramArguments</key>
  <array>
    <string>/usr/bin/python</string>
    <string>/path/to/starterscript.py</string>
    <string>username</string>
    <string>/path/to/.venv/bin/python</string>
    <string>/path/to/your/script.py</string>
  </array>

  <key>WatchPaths</key>
  <array>
    <string>/Users/username/Downloads/</string>
  </array>

  <key>RunAtLoad</key>
  <true/>
</dict>
</plist>

Remember to replace /path/to/starterscript.py, username, /path/to/.venv/bin/python, and /path/to/your/script.py with your actual paths and username.

After creating the .plist file, load it:

launchctl load ~/Library/LaunchAgents/com.example.monitorDownloads.plist

Now, your launchd service is set up to monitor the ~/Downloads folder and will execute your Python script when any change occurs.