How to grant a user to run “sudo sh” without having to typing password?

Question

I want to grant it to a specific user A only, how to do that?

Answer 1

Put:

A ALL=NOPASSWD: ALL

in /etc/sudoers. If you only want to allow sh, change the second ALL to /bin/sh.

Answer 2

Put this in the sudoers:

username ALL=NOPASSWD:/bin/sh

And for the sake of teaching a man how to fish, this info is found in the man file for sudo. Just type in 'man sudo' and you'll get all the info you need.