Rotate display of external monitor on macOS.
- Download and open
RotateDisplay.applescript
withScript Editor
- Modify parameter
externalDisplay
to your secondary monitor's name - Click
Run the Script
to test - Export as application, then you can rotate display by double click the app
- Click
🍎
->System Preferences...
->Displays
- The secondary monitor's name would appear on the title bar of popup window
- like "Acer CB281HK" in the screenshot below: