Mac OS X options for running a Ruby file in the background repeatedly

I wrote a Ruby script that I want to run in the background repeatedly as long as the computer is running. I was planning on using GeekTool to get this .rb file to run in the background, but I'm having issues seen here using Ge开发者_开发百科ekTool to run my script.

The thing is that I want this script to be a complete surprise (it's a message display system for my wife) so I want to be able to have it start running every time her computer starts up and keep running as long as her computer is on. If I can't use GeekTool to do it then I have no idea what to use.

What can I do?

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You use launchd

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Lingon (despite not being actively supported) will help you create a launchd setup, and has quick access to the launchd man pages.

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Geektool ended up working out for my needs after all.