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Basic

§ 2.B: Changing Your Password

It it fairly standard, the first time you log onto a Unix system, to be asked to change your password.

Before picking a password, it is important to consider security. A good password is easy for you to remember and hard for someone else to guess. Here is some good advice from A Scientist's and Engineer's Guide to Workstations and Supercomputers (an excellent paper-based book for scientists and engineers, which, incidently, was written by one of the directors of this project):

Passwords should be at least five characters long. They can be up to eight characters long, including numbers and special characters. Using eight characters makes your password more secure. Try not to use a word in a dictonary or a proper noun because they are so easy to guess just by going through the dictonary. Personal information, like your social security number, phone number or birthday is also easy to guess (as you know from all those spy movies you have been seeing). In particular, do not use your username. Mix letters, numbers, and punctuation. Mix lower and upper case letters, too.

A good way of getting a secure password is to think of a phrase and then take the initial letters of the words in the phrase, randomly capitalizing and adding punctuation. License plate combinations like 10sne1 also work well. Keep several passwords in mind, so you can change your password regularly (every few months or any time you think someone else knows it).

Keep in mind that your password is your own. No one else should know it. Do not share your account with other users by giving your password to them. Depending on the conditions under which your account was given to you, sharing it may be like sharing your driver's license, it is often grounds for revocation. Please do not do it.

Keep your password secure. Do not keep it in a computer file or send it by email.

If you wish to change your password, issue the command:

followed by the return key. (Remember, the > is the computer's prompt, and it may be different on your system.) If your password has expired, Unix may automatically start this command for you. Either way, you will be prompted first for your old password and then for your new password. In fact, you will be prompted several times to enter your new password just to make sure you and Unix got it right.

Be sure to notice if the Num Lock or Caps Lock key has been activated. Unix is case-sensitive, so while both are acceptable, "10sne1" is not the same as "10SNE1".

Ask your system administrator for help when you forget your password.

We will look briefly at logging out, before looking at some basic Unix commands.

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Comments and questions to CP-unix@physics.orst.edu.