kazulog@sv1:~$ sudo usermod -aG sudo taro
kazulog@sv1:~$ id taro
uid=1001(taro) gid=1001(taro) groups=1001(taro),27(sudo),100(users)
kazulog@sv1:~$ su - taro
Password: 
taro@sv1:~$ id
uid=1001(taro) gid=1001(taro) groups=1001(taro),27(sudo),100(users)
taro@sv1:~$ sudo -l
[sudo: authenticate] Password: **************              
User taro may run the following commands on sv1:
    (ALL : ALL) ALL
taro@sv1:~$ sudo whoami
root
taro@sv1:~$ exit
logout