CHAPTER 2 -
LOGGING IN AND OUT

Logging In

When you have established contact with the Unix system, the login prompt will be displayed. You must give your username followed by your password:

login: lnp3jb

Password: secret1 -the password is not in fact displayed when you type it

The username can be up to 8 characters in length. Unix usernames contain only lowercase characters, and it is important that you type your username in lower case (if you don't you will be permitted to log in, and then the shell will not recognise case differences.) The password must normally contain between 6 and 8 characters. On some unix systems the password must contain at least 1 non-alphabetic character.

System messages

When you log in a number of system messages may be displayed. The more filter will be used to control the output if the file contains more than a screenful of information. Just press the space bar to see the next screenful if it says 'more' at the bottom of the screen.

The message:

You have new mail

indicates that electronic mail has been sent to your mailbox.

The prompt

When your login procedure is completed you should see the system prompt. This indicates that the shell is running and is awaiting instructions from the user. The prompt can take many forms, and you can change it later on if you want to. Often the prompt will contain the % character, and a number in brackets. This number will represent the number of a command, and can be used to recall commands already issued. It may also display the name of machine or system that you are logged onto. Some users prefer to have the name of the current working directory displayed in their prompt. For convenience, in this document, the % character will be used to represent the prompt.

Changing your password

Users will be assigned their username and initial password by the unix system administrator. You are advised to change the initial password to one that you will find easy to remember. Use the passwd command to change your password:

% passwd                     -where '%' is the prompt
Changing password for lnp5mw
Old password:                -type in your old password
New password:                -type in your new password
Retype new password:         -and again, to make sure
%

Notice that your passwords are not displayed.

Logging out

When you have finished your unix session you must log out from the system. To do this give the command:

% logout

You should always wait for the message confirming that you have logged out.

Problems?

On some unix systems you may receive the message:

logout: command not known

If this happens you should type:

exit

You may occasionally get the message:

There are stopped jobs

If this happens simply give the logout command again.

PRACTICE

Log in to the unix system using your username and password.Change your password using the passwd command. You may find that the system will not change your password immediately. In this case you may have to use your old password next time that you log on.