Where in your code are you trying to match .pst and .prj?

How does your code currently fail to work?

Is the rest of your setup needed to test the functionality of matching .pst or .prj?

Please provide a short, self contained, compiling example that also has the input data as text. You also might want to read perlre and/or perlretut to learn about regular expressions and how they work. Also see YAPE::Regex::Explain.