Users

UNIX is a multiuser operating system: it was designed to allow many users to work on the same computer, either simultaneously (using several terminals or network connections) or in turns. Under UNIX, to identify yourself to the system, you must log in, which entails entering your login name (the name the system uses to identify you) and your password, which is your personal key for logging in to your account. Because only you know your password, no one else can log in to the system under your user name. Usually people choose their first or last name or some variation of it as their login name, so that if your real name is Sasha Beilinson, your login might be sasha.

Each user has a separate place to keep his files (called his home directory). UNIX has a system of permissions (see the section called Permissions), so that on a properly configured UNIX system a user can't change other users' or system files. This also allows every user to customize various aspects of the system — in particular, GNOME behavior — for himself, without affecting other users.

On any UNIX system there is also a special user, called system administrator, with the login name root. He has full control over the system — including full access to all the system and users' files. He has the authority to change the passwords of existing users and add new users, install and uninstall software, and so on. The system administrator is usually the person responsible for proper functioning of the system, so if you have some problems, you should ask him.

IMPORTANT

Even if you are the only user on your computer (for example, if the computer is your personal workstation), so that you are also the system administrator, it is important that you create a user account and use it for daily work, logging in as root only when necessary for system maintenance. Because root can do anything, it is easy to make mistakes that have catastrophic consequences. Picture the root account as a magic hat that gives you lots of power, with which you can, by waving your hands, create or destroy entire cities. Because it is easy to wave your hands in a destructive manner, it is not a good idea to wear the magic hat when it is not needed, despite the wonderful feeling.