Touch wood but my PB pipes have not leaked. I am posting this question as a proactive measure.

Assume that I develop a leak in a PB pipe in my home. I would like to "buy" sometime before calling in a plumber to replace the entire system with copper or PEX. Therefore, I would like to add a shut off valve or termination cap at the leak as a temporary fix. How do I do this?

In addition, is it possible as a long term fix to cut out the leak and then make the following connection PB-PEX-PB? What do I need?