To change your password on UNIX systems, follow these steps:
Courtesy : unix-mauals website

1. Log into the system using your old password, if you are not already logged in.

2. At the prompt, use the command:

$ passwd

3. Usually, you will be asked to enter your old password first. This is a security measure, designed to help prevent someone else from changing your password:

$ passwd

Enter old password:

Note that when you enter your old password, it will not be displayed.

4. (Note that, if you are being forced to change your password as part of logging in, you will come straight to this stage). You will be asked to enter your new password:

$ passwd

Enter old password:

Enter new password:

Note that when you enter your new password, it will not be displayed.

5. You will then be asked to re-enter your new password. This is designed to make sure that you...