Why doesn't /proc exist in OS X? What is the reason that /proc does not exist in OS X? I was curious to find file descriptors that a process was using in my Mac. The way I do it in linux is to go in /proc/fd folder of that process.

How do I find what fds are used by a process?
Going back to basics : Ubuntu is a GNU/Linux, OS X is a FreeBSD : Different systems, different way to work. 

On OS X you can use lsof to see the open files. 

$lsof -p 68180


would show you every files opened by the process with pid 68180.