Apply a global shader

Is there a quick easy way to apply a global shader to the entire scene?

Im sure I can figure out the long way to do it, I just wanted to make sure there wasnt a function that already accomplished this.

I want to use it to toggle my version of an overdraw mode in game.


Thanks for the comment above, for other peoples referance Ill just reiterate what they said so the question could be marked answered.

Camera.main.SetReplacementShader(Your shader);//sets a global shader in that camera
Camera.main.ResetReplacementShader(); // resets back to the original