System User's Guide: Operating System and Devices

Login and Logout Overview

To use the operating system, your system must be running and you must be logged in. When you log in to the operating system, you identify yourself to the system and allow the system to set up your environment.

This section describes the following procedures:

Logging In to the Operating System

Your system might be set up so that you can only log in during certain hours of the day and on certain days of the week. If you attempt to log in at a time other than the time allowed, your access will be denied. Your system administrator can verify your login times.

You log in at the login prompt. When you log in to the operating system, you are automatically placed into your home directory (also called your login directory).

After your system is turned on, log in to the system to start a session.

Type your login name following the login: prompt and press Enter:
```
login: LoginName
```
For example, if your login name is denise:
```
login: denise
```
If the password: prompt appears, type your password and press Enter. (The screen does not display your password as you type it in.)
```
password: [your password] 
```

If the password prompt does not appear, you have no password defined; you can begin working in the operating system.

If your machine is not turned on, do the following before you log in:

Set the power switches of each attached device to On.
Start the system unit by setting the power switch to On (I).
Look at the three-digit display. When the self-tests complete without error, the three-digit display is blank.

If an error requiring attention occurs, a three-digit code remains, and the system unit stops. See your system administrator for information about error codes and recovery.

When the self-tests complete successfully, a login prompt similar to the following displays on your screen:

login:

After you have logged in, depending on how your operating system is set up, your system will start up in either a command line interface (shell) or a graphical interface (for example, AIXwindows or Common Desktop Environment (CDE)).

If you have questions concerning the configuration of your password or user name, please consult your system administrator.

Logging in More Than One Time (login Command)

If you are working on more than one project and want to maintain separate accounts, you can have more than one concurrent login.You do this by using the same login name or by using different login names to log in to your system.

Note: Each system has a maximum number of login names that can be active at any given time. This number is determined by your license agreement and varies among installations.

For example, if you are already logged on as denise1 and your other login name is denise2, at the prompt, type:

login denise2

If the password: prompt displays, type your password and press Enter. (The screen does not display your password as you type it.) You now have two logins running on your system.

See the login command in the AIX 5L Version 5.2 Commands Reference for the complete syntax.

Becoming Another User on a System (su Command)

You can change the user ID associated with a session (if you know that user's login name)by using the su (switch user) command.

For example, if you want to switch and become user joyce, at the prompt, type:

su joyce

If the password: prompt displays, type joyce's password and press Enter. Your user ID is now joyce. If you do not know the password, the request is denied.

To verify that your user ID is joyce, use the id command. For more information on the id command, see Displaying User IDs (id Command).

See the su command in the AIX 5L Version 5.2 Commands Reference for the complete syntax.

Suppressing Login Messages

After a successful login, the login command displays the message of the day, the date and time of the last successful and unsuccessful login attempts for this user, and the total number of unsuccessful login attempts for this user since the last change of authentication information (usually a password). You can suppress these messages by including a .hushlogin file in your home directory.

At the prompt in your home directory, type:

touch .hushlogin

The touch command creates the empty file named .hushlogin if it does not already exist. The next time you log in, all login messages will be suppressed. You can instruct the system to retain only the message of the day, while suppressing other login messages.

See the touch command in the AIX 5L Version 5.2 Commands Reference for the complete syntax.

Logging Out of the Operating System (exit and logout Commands)

To log out of the operating system, do one of the following at the system prompt:

Press the end-of-file control-key sequence (Ctrl-D keys).

Type exit and press Enter.

Type logout and press Enter.

After you log out, the system displays the login: prompt.

Stopping the Operating System (shutdown Command)

Attention: Do not turn off the system without first shutting down. Turning off the system ends all processes running on the system. If other users are working on the system, or if jobs are running in the background, data might be lost. Perform proper shutdown procedures before you stop the system.

If you have root user authority, you can use the shutdown command to stop the system. If you are not authorized to use the shutdown command, simply log out of the operating system and leave it running.

At the prompt, type:

shutdown

When the shutdown command completes and the operating system stops running, you receive the following message:

....Shutdown completed....

See the shutdown command in the AIX 5L Version 5.2 Commands Reference for the complete syntax.