PHP Exec sudo mount抛出花哨的错误消息

Question

I'm using Centos7 OS, I have this script that mount a folder from windows PC

exec('sudo mount -t cifs -o username="'.$user.'",password="'.$pass.'",dir_mode=0777,file_mode=0777 
//'.$ip_address.'/c/kitpos/update /mnt 2>&1',   $output, $results);

And I got this fancy error message that looks like a permission issue.

Array
(
    [0] => 
    [1] => We trust you have received the usual lecture from the local System
    [2] => Administrator. It usually boils down to these three things:
    [3] => 
    [4] =>     #1) Respect the privacy of others.
    [5] =>     #2) Think before you type.
    [6] =>     #3) With great power comes great responsibility.
    [7] => 
    [8] => sudo: no tty present and no askpass program specified
)

My /mnt folder ownership and permission is root and 777 but even if I change it www-data:www-data which is my php running as, still got the same error.

777 drwxrwxrwx 2 root root 4096 mnt

I also have an Ubuntu server but it works fine in their with that same code. Does anyone have an Idea?