Hi guys! Today, I post this topic for someone who have problem with mobile terminal. After jailbreak, Many people can not log in to mobile terminal. The message is: "su: cannot set groups: operation is not permitted".

Now, This is a solution:

Login as root using WinSCP (or any other ssh application) and go to root directory ( It is not the var/root)

Press Ctrl+T and type the following command:

chmod u+s /bin/su


now when you try su in mobile terminal it will work as it should be

credits go to systron from linuxquestions