How to programmatically add exception for unidentifed .app

Question

When I create a .app on the desktop of mac os x 10.9, and when user clicks it, they get "unidentified developer" error.

However if they right click, then click open, then from dialog box click open, it adds an exception so in future launches it doesnt throw the "unidentified developer" error and launches.

I was wondering what is the programmatic way or command line or carbon or cocoa api to programmatically add this exception. i know code signing is an option but that requires purhcase of 100$ license, i just want to make a shortcut on the desktop for users of my addon.

image of adding exception with right click > open > open:

Answer 1

It's possible to remove the Quarantine Flag xattr from your application using:

xattr -d com.apple.quarantine My.app