Execute Terminal Command On New Post

I have a localhost installed version of the latest WordPress on my server, and have begun designing my own plug, but am trying to learn a bit more about how WordPress works first.

I’m currently looking for a method to execute a terminal command (or just an application that runs on the server) every time a new post has been created. Even better if possible, to run a different command depending on what category the post was made in. Is something like this possible? Thanks in advance!