Linux Ubuntu16.04 I got a little scary error when I ran a command using sudo

Purpose

--I will summarize the story that solved the error that occurred when logging in to the created user and executing the command with sudo immediately after creating the user.

Conclusion

--The newly created user was not added to the sudo group.

What happened

--When I executed the command with sudo, the following error occurred. The user of the execution environment is miriwo.

```terminal
$ sudo su
[sudo] password for miriwo:
>miriwo is not in the sudoers file. This incident will be reported. (Japanese translation:miriwo is not registered in the sudoers file. This incident was reported.)
```

Work done

1. Log in to the Linux machine as a user with administrator privileges and execute the following command to create user miriwo.

   $ sudo adduser -a miriwo
   

2. Log in to user miriwo and execute the following command.

   $ sudo su
   

3. I got the following error after entering the password for user miriwo.

   miriwo is not in the sudoers file. This is incident will be reported
   

Solution

1. Log in to the Linux machine as a user with administrator privileges and execute the following command.

   $ sudo gpasswd -a ookawa sudo
   

2. For confirmation, log in to the Linux machine again as user miriwo and execute the following command.

   $ sudo su
   

3. Confirmed that the error disappeared.