保存vim打开的readonly文件

一，输入密码：
:w ! sudo tee % > /dev/null
[sudo] password for user:

二，这里按 L键重新将该文件载入缓冲区。
Press ENTER or type command to continue
W12: Warning: File “/etc/profile” has changed and the buffer was changed in Vim as well
See “:help W12” for more info.
[O]K, (L)oad File: