You can configure the Login window and process in several ways:
Control how user accounts appear in the window.
Enable/disable the Automatic Login mode.
Show/hide the Sleep, Restart, and Shut Down buttons.
Enable fast user switching.
You can configure several aspects of how user accounts appear in the Login window:
Log in under an administrator account and open the Accounts pane of the System Preferences utility.
Click the Login Options button (see Figure 2.8). On the right side of the window, you will see the Login Options tools.
To display empty Name and Password fields in the Login window instead of a list of the user accounts you have configured, click the "Name and password" radio button.
When this button is selected, you have to type the name or the short name and password for an account to log in to it. To display the list of user accounts, click the "List of users" radio button instead. With this option, each account (and its image) appears onscreen. To log in, the user clicks her account, enters her password, and clicks the Login button.
Quit the System Preferences utility. The next time the Login window appears, it will reflect the changes you made.
When you started Mac OS X for the first time, you were in the Automatic Login mode. In this mode, you don't have to enter login information; Mac OS X does it for you. This means that you don't have to enter a username and password each time you start or restart your machine; by default, the first user account (created during the Mac OS X installation process) is used.
You should enable Automatic Login mode only if you are the only person who uses your Mac. If you enable Automatic Login mode with the administrator account, you provide access to many of your system's resources, which is an unsecure way to operate. However, if you have a Mac in a secure location and are the only person who uses it, the Automatic Login mode eliminates the need to log in every time you start or restart the machine.
If you are going to enable Automatic Login mode, create a nonadministrator account to use. That way, even if someone does get access to your Mac, he won't be able to use the administrator account. Of course, you might have to log out and then log back in as the administrator, but this strategy provides a good compromise between security and convenience.
To configure the Automatic Login mode, use the following steps:
Open the Accounts pane of the System Preferences utility.
Click the Login Options button.
To enable automatic login mode, check the "Automatically log in as" check box and select the user account that should automatically be logged in on the pop-up menu. The password prompt sheet appears, and the user account you selected on the pop-up menu is selected in the sheet.
Enter the password for the account that you want to be automatically logged in when the Mac starts up.
The next time you start or restart your Mac, the account you specified is automatically logged in and you move directly to the desktop for that account.
This setting affects only the start or restart sequence. When you log out instead of shutting down or restarting, you still see the Login window again and have to log in to resume using the Mac.
To disable automatic login, uncheck the "Automatically log in as" check box.
If you enable Automatic Login mode, you might run into trouble if you leave the Restart and Shut Down buttons enabled. Here's how that could happen. Say you are using your Mac and decide that you want to take a break for a while, but there are people in your area whom you don't want to be able to use the machine while you step away. You log out, and your machine is protected, right? Not necessarily. If the Restart and Shut Down buttons are enabled, someone can restart the Mac from the Login window and then it would start up in the automatic account, giving the person access to the machine. Disabling these buttons prevents someone from using them to access an account that is automatically logged into.
The previous scenario might make you pause to ask a question before you enable Automatic Login mode. If you do disable the Restart and Shut Down buttons and then log out, can someone simply press the hardware Restart or Reset button on the CPU to start up the Mac to automatically log in to the automatic login account? This would bypass the protection offered by disabling the buttons, right? Nope; when the Mac is not shut down properly (by using the Shut Down command), the automatic login feature is disabled when the machine is started or restarted the next time. So, if you have to use one of those buttons, you must log in the next time you start or restart the machine.
To disable the Sleep, Restart, and Shut Down buttons, do the following:
Open the System Preferences utility and then the Accounts pane, and then click the Login Options button.
Check the "Hide the Sleep, Restart, and Shut Down buttons" check box.
Quit the System Preferences utility.
When the Login window appears, these buttons are hidden and the only way to use the Mac is to log in under a valid account.
When a user logs out of his account, all documents are closed and all applications and processes are quit. When a user logs in again, any of these must be restarted to get back to where the user was when he logged out. Prior to Mac OS X version 10.3, this process had to be suffered every time users changed. Under Mac OS X 10.3, you can take advantage of fast user switching. What this means is that you can log in to another user account without logging out of the accounts that are currently logged in. This is very nice because you can leave applications and documents open in an account and log out to prevent someone from using those items. And, another user can log in and work with his account. When he is done, you can log back in to your account and everything will be as it was when you left it. This saves a lot of time and hassle reopening items, and processes you are running can continue to run while another user is logged in to the machine.
To enable this feature, do the following steps:
Open the Accounts pane of the System Preferences application and click the Login Options button.
Check the "Enable fast user switching" check box. A new menu appears in the upper-right corner of the screen, and the account name under which you are currently logged in appears as the menu name.
Quit the System Preferences application.
Logging in and out of accounts can be done with the User Switching menu (see Figure 2.9).
To log in under another account, select it on the menu. You will see the Login window with the account you selected (see Figure 2.10). Enter the password for the account and click the Log In button. After a cool, 3D spinning effect, that user is logged in and his desktop appears.
Sadly, not all hadware can handle the spinning 3-D effect. If you use an older Mac, you might not get to enjoy this cool effect.
If you create a user account without a password and enable the Fast User Swtiching feature, you can log in to the account without a password immediately by choosing it on the user list. You bypass the login window altogether.
To temporarily block access to the current user account without logging out, open the User Switching menu and select Login Window. The Standard Login window appears. You can leave the machine without worries that someone will be able to access your account. When you are ready to log in?or when anyone else is, for that matter?select the user account, enter a password, and click Login (you get to see the cool 3D spin again, too).
On the User Switching menu and in the Login window, users who are currently logged in have a check mark next to them.
If another user account is logged in and you attempt to restart or shut down the machine, a warning dialog box appears that explains that other users are logged in and the action you are taking could cause them to lose data. If you enter an administrator username and password and click Shut Down or Restart, the other users are logged out and the action you want is performed.