A unique feature of the Silicon Graphics IRIX operating system is support for simultaneous multiple users on the same system. This means:

 
Two or more people can be using the same system at the same time. Although only one person can be physically seated in front of the system, others can use it via the network that connects many computers in an office environment.


To keep this situation manageable, each person who uses the system has to "log in" to it under a special identity, called their "user" or "login" name. Once this identity is created, you have your own user account.

Your workstation is like a shared house with personal rooms. If you think of the workstation as a home, your login name is your own personal door into the home, and your user account is the room you enter through that door.

 

What are the guest and the root accounts for?

When you turn on your system, you typically see something like the image above. This is called the login screen. The icons at the top represent different login accounts. You'll notice that even if you are the only person with an account on your system you still have at least two other accounts in addition to your own: the guest account and root account.

 

Guest is for casual use

The guest account provides a way for you to log in when you do not yet have your own account. It also provides remote users (people logging in from other systems) or casual users limited access to your system. However, you can protect any files you have by putting a password on your account (you'll learn about this in Figure Out How to Become Secure With System Security and "Permissions"). The guest account is actually one way of providing you some security. Someone who only needs to use the system temporarily to do a limited task like create a document, could log in as guest instead of logging in to your own account. As guest, they would not be working in the area where you keep your files on the system.

 

Root is for system administration

If your user account is equivalent to your own room in the house, the root account is like full-house access. However, the root account is not for everyday use. When you log in as "root," you can act as a system administrator to the workstation. For example, you can add, delete, and modify essential system files, install software, or add a disk drive to your system. You must use the "root" account in order to perform these tasks.

You'll find that you don't necessarily need to log out of your personal account and then log in to the "root" account in order to perform some functions with "root" privilege. Often the system administration programs on your system will prompt you for a root password to allow you to temporarily act as the root user for the duration of a specific task.