Most administrative tasks such as adding users require that you log in as root (UID=0) first. The root account is also known as the superuser account because it's used to make system changes and can override user file protection in emergency situations.
The superuser account should be used only to perform administrative tasks to prevent indiscriminate changes to the system.
You can either log into the system as superuser or use the su(1M) command to change to the superuser account.
If you are using role-based access control, you must assume a role (either superuser or some other role) to perform administrative tasks. Roles are assumed by using the su command; you cannot log in to a role directly. See "Role-Based Access Control" in System Administration Guide, Volume 2 for more information.
Become superuser by one of the following methods. Both methods require that you know the root password.
Change to the superuser account by using the su command.
% su Password: root_password #
The pound sign (#) is the Bourne shell prompt for the superuser account.
Log in as superuser on the system console.
hostname console: root Password: root_password #
This method is not enabled by default. You must modify the /etc/default/login file to log in as superuser on the system console. See "Securing Systems (Tasks)" in System Administration Guide, Volume 2 for information on modifying this file.