/System/Library folder on macOS Sierra does not allow permissions modifications. Is there an override?

Question

I am trying to create a folder and move some files around in /System/Library on macOS Sierra.

1. Terminal's "mkdir" command returns "Operation not permitted".
2. Hitting CMD+I shows that the folder is not locked. Only system has the Read & Write privilege. When trying to modify the privilege for "everyone", or just adding my user account to the list, the following warning pops up: "The operation can’t be completed because you don’t have the necessary permission."

Has Apple completely locked the end user out of the System folder? Is there no way I can make changes in there now?

Answer 1

This is the macOS System Integrity Protection (SIP) which prevents access to key system directories and files even for root.

You can disable SIP by booting in to recovery mode and running csrutil disable in Terminal.