Here are the steps I take to associate .dig files to autostart the Digital application on double-click. Normally a script/shell file can’t be associated to an extension in macOS. To solve this I make a small “app” using the built-in Automator application and have that run a script that runs Digital. Please note that these intructions assume that you have installed the Digital “jar” file in /Applications/Digital If you’re having it somewhere else you need to adjust the Automator code.