Atopsy

One of the most hidden and less known under the hood upgrades Apple did to El Capitan was a brand new System Integrity Security System (alot of system in there), or rather known to the El Capitan community as Rootless. Rootless was developed to increase security over your Mac's system files, meaning your system will lock you out of important apps and files for the OS, files that the system needs to even boot. The main aim for this system is to prevent any accidental or intentional tempering or removal of system files and to prevent viruses from bricking your Mac. There is a way to disable it and don't worry, this process will not brick you...