因为用隐藏登陆页面其他用户的命令，出现了，然后恢复true之后进root编程中文的。然后再隐藏。
To hide 'Others...' from the login window, please type the following command in Terminal:
sudo defaults write /Library/Preferences/com.apple.loginwindow SHOWOTHERUSERS_MANAGED FALSE
It will prompt you to enter your admin password.
To unhide 'Others...' from the login window, use the same command but type TRUE at the end of the command instead of FALSE or you can delete the com.apple.loginwindow.plist from the Preferences folder.
Hope this helps,
