Automatic printing of files written in specific directory

I have a legacy application that for printing purposes, sends its output to a file in different directories. What's written into directory X is printed in printer X; what's written into directory Y is printed in printer Y; and what's written into directory Z is converted into a PDF, and the PDF handler program is launched.

This setup works fine in Windows.

I'd like to replicate it in Ubuntu Linux. So I'd like a daemon that would monitor a directory, so that it would send whatever is written into that directory to a specific printer queue.

Any help would be greatly appreciated.