[daily][centos][sudo] sudo 报错

有时候, 比如在CentOS 6上. sudo 会报如下错误:

sudo: must be setuid root

这是因为, sudo 命令, 没有SUID, 

[root@T209 ~]# ll /usr/bin/sudo
-rwxr-xr-x. 2 root root 219272 Jun 22  2012 /usr/bin/sudo

使用如下命令, 增加SUID:

[root@localhost ~]# chmod u+s /usr/bin/sudo
[root@localhost ~]# ll /usr/bin/sudo
-rwsr-xr-x. 2 root root 219272 Jun 22  2012 /usr/bin/sudo

参考:https://www.sudo.ws/troubleshooting.html

Q) Sudo compiles and installs OK but when I try to run it I get:
    effective uid is not 0, is /usr/local/bin/sudo on a file system with the
    'nosuid' option set or an NFS file system without root privileges?
A) The owner and permissions on the sudo binary appear to be OK but when
   sudo ran, the setuid bit did not have an effect.  There are two common
   causes for this.  The first is that the file system the sudo binary
   is located on is mounted with the 'nosuid' mount option, which disables
   setuid binaries.  The output of the "mount" command should tell you if
   the file system is mounted with the 'nosuid' option.  The other possible
   cause is that sudo is installed on an NFS-mounted file system that is
   exported without root privileges.  By default, NFS file systems are
   exported with uid 0 mapped to a non-privileged uid (usually -2).  You
   should be able to determine whether sudo is located on an NFS-mounted
   filesystem by running "df `which sudo'".