Most Ubuntu users never have a problem here, but sometimes, people who like to experiment break things, especially while learning. This section exists to help you first understand more completely how
sudo works and also how to restore
sudo access to a specific user when, for some reason, it has ceased to function for that user.
You will usually know a problem has occurred because an error message like this will appear when a user tries to issue a command using
matthew@seymour:~$ sudo shutdown -h now[sudo] password for matthew:matthew is not in the sudoers file. This incident will be reported.
Sometimes, you might not even receive an error message, but the command issued simply ...