Multiple Users 
How to let a family work on one Mac.
Working together on one computer has its advantages:
- everyone has his own home folder with his own files
- everyone has is own program settings, Email, music files, movies et-cetera
- those files are separate, so no issues with altered or missing files
- of course you can share files also
- you only have to buy one computer (and make a very good schedule...)
Resume: when you log on, the Mac is adapted to your needs. When your fiancée logs on, the Mac fits hers/his.
How does this work?
All users reside in the 'Users' folder on the first level of your hard disk. In a schematic way, it looks like this:
The sharing of files goes through a folder "Shared". In this case, the folder is for two users, 'macmiep' and 'macmiepcursus':
So, if you want to work on a Mac with more than one person, you need to configure another user account.
To add a new user.
Go to System Preferences and choose 'Users'. Hit the '+' button and choose a log on name and a password.
Next, you tell the Mac what this user is or isn't allowed to do:
For example: you'd like your children to use the Mac for games, but not to surf the internet or e-mail: you can configure this here. As long as you keep your Administrator password to yourself, they won't be able to.
Users and their privileges
In a multi user system, it is wise to determine what users can and cannot do on the computer. Who is allowed to change critical system preferences, use certain programs, and look into certain folders? There are two kinds of users.
Note: in fact: there are three, more about that later
The user called 'Administrator'
This user has the right to change all System Preferences, make new user accounts and use all programs. The lock symbol you can see in the lower left of most System Preferences give the Administrator the opportunity to protect these preferences against unauthorized changes. Is the lock closed (click on it to close or open it) an administrator user name and password has to be provided before any changes can be made:
The user called 'User'
The User is allowed to work with the Mac and do anything the Administrator has allowed him to do, in any detail. This can be useful with young children. If you want to allow them to play games but not to go on the Internet or Email, it can be done easily.
As long as the Administrator keeps his password to himself, the Mac always remains in the condition you want it to!
How do I know what I can or cannot do on my Mac?
When you start up a forbidden program, the Mac will tell you that you do not have the privileges to do so and won't start up the program. Folders that are forbidden have a 'wrong way' road sign on them:
Choose 'Info' from the 'Archive' Menu to see what you are or aren't allowed to do with a folder, file or Program:
TIP
Background information on the User subject
On a Unix system, every file has a code attached to it which tells who is allowed to use or change it. Normally, you won't see that code at all, only when you are a Unix geek or interested in the command user interface in the Terminal program. For those geeks, it is possible to work at the Mac with only typing text commands. The normal Mac user won't need them ever, but it is useful to know of its existence.
A die-hard Unix or Linux user can eat his heart out:
Switching from one user account to another
It is possible to be logged on with more users at a time. To switch from one user to another, go to the upper right corner of your screen and click on your username (here: 'MacMiep)
The Mac asks for a password:
After typing it correctly the screen will turn to the next user like it’s a cube:
You can switch back and forth with users without changing anything. All open files and programs stay open. It's like there are two computers at work on only one screen!
You can also log out at the Apple Menu and log on again with another user name.
TIP
Removing users.
At System Preferences => Users it is possible to remove a user easily. This can only be done from an Administrators account and the user cannot be logged on at the time of removal:
However, it is more difficult to remove an Administrator account. The best way to do it is first to make an other Administrator account, log on with it and remove the old one.
NetinfoManager
More experienced administrators can also use the NetInfoManager to edit users. You can find this in Programs => Utilities.
Note: This is a dangerous program. Beware you know what you're doing in case you use it!
Open the lock and select 'users'. Choose the user you want to edit or remove.
Playing God?
In every Unix-port, so also in Mac OS X, you can find the so-called 'root' user. With the user name 'root' and its password you can do ANYTHING in a Unix System. "Anything" really means anything!
The Root User is the most powerful person at the machine. This means that you can destroy the Operating System totally and look into any file or folder!
This is why Apple disables the Root account in the standard Mac OS X configuration, for security reasons. But sometimes it can be necessary or useful to activate the root account and log on as 'root'.
When you are not familiar with Unix or Linux: KEEP AWAY FROM THE ROOT ACCOUNT!
For the Power User or the brave ones among you: The root-account can be activated this way:
Go to Programs => Utilities and open NetInfoManager. Confirm your Administrator identity at the 'Security' menu. Then choose 'Enable Root User'.
Now go to System Preferences => Users and make a new user account. User name: root. Choose you password very, very well.
Now log out and log on with the root account.
When you're done with working as Root, log out immediately. Log on again in your administrator account. Go immediately to 'NetInfoManager' and de-activate the root account.
Never use the root account as a standard user account!
It is better never to activate the root account. You can work as a root for five minutes at a time when you use the 'sudo' command in Terminal. In the chapter Unix and X11 you'll see how.
ANYTHING YOU DO AS 'ROOT' IS AT YOUR OWN RISK!
(Apple doesn't support it at its help-desk either)
Disclaimer: Use of the information and data contained within this site is at your sole risk. If you rely on the information on this Site you are responsible for ensuring by independent verification its accuracy, currency or completeness. Copyright of all screenshots: Apple Computer Inc.