NOTE FIRST CREATE THE APP using the method below and then add to the user login Options:
Create an APP:
- start Automator.app
- Select "Application"
- click "Show library" in the toolbar (if hidden)
- Add "Run shell script" (from the Actions/Utilities)
- Copy&paste your script into the window
- Test it
- Save it as Application
- Open Users/login option and select this app