I'm not in sudoers:
..... is not in the sudoers file. This incident will be reported.
How can I sudo in this terminal window, without switching user?
The well-known command
sudo -u administrator -i also gives the above message.
Say your admin account name is admin, then:
Then you are the admin user...
And Gordon Davisson has a good suggestion. When you're a user with admin rights, you can use sudo to get root rights even if there is no root user. And you can use "sudo john" to become user John without knowing his password.
You will once have to become an Admin-user with
There you can scroll down to the end and add a line for yourself like
Oh, and when you use
Make sure your account is an admin user, not just a regular user. Go to system preferences, users, and check the box labelled "Allow user to administer computer".