Questions about: visudo

Who can execute ‘sudo’?We can run ‘/usr/sbin/visudo‘ to add/remove the list of users who can execute ‘sudo‘. $ sudo /usr/sbin/visudoA screen shot of ‘/usr/sbin/visudo‘ file, looks something like this: The sudo list looks like the below string, by def
I'm using ubuntu server 12. 04 LTS I want to know how to configure my sudoers file (obviously, using visudo), to permit an user to run commands like root (doing something like "sudo service x restart") but without the permission to be root (doing "su