问题：
sudo:sudo /etc/sudoers is world writable
sudo:no valid sudoers sources found ,quitting
sudo:unable to initialize policy plugin
#无法使用chmod修改权限 demo:Desktop piaoyu.qiu$ ls -la /etc/sudoers -rwxrwxrwx 1 root wheel 1371 8 9 11:28 /etc/sudoers demo:Desktop piaoyu.qiu$ chmod 440 /etc/sudoers chmod: Unable to change file mode on /etc/sudoers: Operation not permitted #切换到root用户 demo:Desktop piaoyu.qiu$ su Password:你自己设置的密码 sh-3.2# ls -l /etc/sudoers -rwxrwxrwx 1 root wheel 1371 8 9 11:28 /etc/sudoers sh-3.2# chmod 0440 /etc/sudoers sh-3.2# ls -l /etc/sudoers -r--r----- 1 root wheel 1371 8 9 11:28 /etc/sudoers sh-3.2# exit