yourname is not in the sudoers file.This incident will be reported.

1.切换roo用户

su -

2.添加写的命令

chmod u+w /etc/sudoers

3.编辑sudoers文件

vi  /etc/sudoers

4.按键盘i

5.找到root ALL=(ALL) ALL，复制到下一行 yourname ALL=(ALL) ALL

6.去掉写命令

chmod u-w /etc/sudoers