Is there an event emitter in Linux and where can I learn more about them?

Question

linux

I need to include a script when ip changes. Where exactly to catch the event and is it possible to hang the handler using bash?
What Linux events generate events (you can just link to the materiel)?
You can just hang a python/nodejs script in a loop to check some log file or command output, but wouldn't that be a waste of CPU resources, or do any Linux event handlers act like that anyway?
I want to efficiently process events, changes in directories, files.

Answer 1

changes in directories, files

https://en.wikipedia.org/wiki/Inotify