给用户授权以root身份执行ls,touch,passwd命令，但是禁止修改root用户密码
通过visudo修改授权普通用户相关的权限
[root@lin ~]# visudo
oldboy ALL=(ALL) /bin/ls, /bin/touch, /usr/bin/passwd, !/usr/bin/passwd root
[root@lin ~]# visudo
oldboy ALL=(ALL) /bin/ls, /bin/touch, /usr/bin/passwd, !/usr/bin/passwd root
登录普通用户，并试验结果
[root@lin ~]# su - oldboy
[oldboy@lin ~]$ sudo passwd lin666
Changing password for user lin666.
New password:
BAD PASSWORD: it is too simplistic/systematic
BAD PASSWORD: is too simple
Retype new password:
passwd: all authentication tokens updated successfully.
[oldboy@lin ~]$ sudo passwd root
[sudo] password for oldboy:
Sorry, user oldboy is not allowed to execute '/usr/bin/passwd root' as root on lin.
[root@lin ~]# su - oldboy
[oldboy@lin ~]$ sudo passwd lin666
Changing password for user lin666.
New password:
BAD PASSWORD: it is too simplistic/systematic
BAD PASSWORD: is too simple
Retype new password:
passwd: all authentication tokens updated successfully.
[oldboy@lin ~]$ sudo passwd root
[sudo] password for oldboy:
Sorry, user oldboy is not allowed to execute '/usr/bin/passwd root' as root on lin.