After OS X upgrades to El Capitan, it provides a security-related pattern called SIP (System Integrity Protection), also known as rootless mode, which is a new feature that emphasizes security for OS X, which prohibits the software from being used as root in Mac running on, upgrade to OS X 10.11 Maybe you'll see some apps are disabled so that/usr/bin folders we can't read and write properly, but it also causes some programs (such as homebrew and Git) to execute exceptions in command-line mode.
SIP presets are developed, and the following steps can be used to close the SIP:
1, restart the MAC, hold down the COMMAND+R key until the Apple logo appears, into Recovery Mode
2, click Utilities > Terminal
3, in the Terminal input csrutil Disable, and then enter
4, restart the MAC
This allows SIP security to be turned off and, if you want to reopen the security setting, repeat the above steps and replace the command with Csrutil enable in step three.