Section 3: Logging In and Logging Out
To ensure security and organization on a system with many users,
UNIX machines employ a system of user accounts. The user accounting
features of UNIX provide a basis for analysis and control of system
resources, preventing any user from taking up more than his or her
share, and preventing unauthorized people from accessing the system.
Every user of a UNIX system must get permission by some access control
mechanism.
Logging in
Logging in to a UNIX system requires two pieces of
information: A username, and a password. When you sit down for a UNIX
session, you are given a login prompt that looks like this:
- login:
Type your username at the login prompt,
and press the return key. The system will then ask you for your
password. When you type your password, the screen will not display
what you type.
Your username
Your username is assigned by the person who creates your account. Your
username must be unique on the system where your account exists
since it is the means by which you are identified on the system.
Your password
When your account is created, you are promted to choose a password.
If you need to change your password, you must contact the system
administrater in room 409 CB. Efforts are being made that will soon
enable users to update their passwords on their own.
Some guidlines to follow when selecting a password are:
- Do not use any part of your name, your spouse's name, your
child's name, your pet's name, or anybody's name. Do not use any
backward spellings of any name, either.
- Do not use any number that can be easily guessed, like your phone number,
your social security number, your address, license plate number, etc.
- Do not use any word that can be found in an English or
foreign-language dictionary.
- Do not use all the same letter, or a simple sequence of keys
on the keyboard, like "qwerty".
- Do use a mix of upper-case and lower-case letters,
numbers, and control characters.
- Do use at least six characters.
If you have accounts on multiple machines, use a different password on
each machine. Do not choose a password that is so difficult to
remember that you must write it down.
Logging Out
When you're ready to quit, type the command - exit
Before you leave your terminal, make sure that you see the
login prompt, indicating that you have successfully logged out. If
you have left any unresolved processes, the UNIX system will require
you to resolve them before it will let you log out.