$ sudo visudo
Hit the “I” key, to switch the vi editor into INSERT mode
Add user “foo” to the list of sudoers, by adding a new line:
foo ALL=(ALL) ALL
Hit the “ESC” key, to leave the INSERT mode
Hit the “:” key, to switch to “COMMAND” mode
Enter “wq” at the prompt to save and exit – or –
Enter “qa!” at the prompt to exit without saving
:wq
