Mac due to incorrect use chmod -R 777 command to change the / usr / bin cause the terminal can not practical, the perfect solution to remind the process has ended!

1. do not delete any files.

2. Start the root user privileges

4. Gordon into the root user

5. Use the terminal user to enter commands in the root

    chown root:wheel /usr/bin/login 

    chmod u+s /usr/bin/login

6. Close the terminal, switching users, using the original end user may have a problem with use of the terminal.

　　　　The above is thinking, practical and reliable. believe me!

　　　　Fool-operation reminder: System Preferences -> Users & Groups -> Login Options -> Network Account Server - join (you can click on the little lock operation) ---------

　　　　　　　　　　　　The process is completed in the top row of the screen, click Edit to start the root user's option appears, and then exit the account, you can switch to the root login password is just above the operating time will

　　　　　　　　　　　　To remind you to set a password.