macos - Which folders are affected by System Integrity Protection?

I have trouble writing files with sudo to /Library under OSX v10.11.3. It seems the folder is affected by SIP. Which folders fall under SIP?

Answer

See Apple's About System Integrity Protection on your Mac:

Paths and applications protected by System Integrity Protection include:

• /System


• /usr


• /bin


• /sbin


• Apps that are pre-installed with OS X

Paths and applications that third-party apps and installers can write to include:

• /Applications


• /Library


• /usr/local

System Integrity Protection is designed to allow modifications of these protected parts only by processes that are signed by Apple and have special entitlements to write to system files, like Apple software updates and Apple installers.