The su command

4.4.3.1. The su Command

Upon typing the su command, the user is prompted for the root password and, after authentication, given a root shell prompt.

Once logged in via the su command, the user is the root user and has absolute administrative access to the system. In addition, once a user has attained root, it is possible in some cases for them to use the su command to change to any other user on the system without being prompted for a password.

Because this program is so powerful, administrators within an organization may wish to limit who has access to the command.

One of the simplest ways to do this is to add users to the special administrative group called wheel. To do this, type the following command as root:

usermod -G wheel <username>