passwd command changes passwords for user accounts. A normal user may only change the password for his/her own account, while the super user may change the password for any account. passwd also changes account information, such as the full name of the user, the user’s login shell, or his/her password expiry date and interval.
If you wish to immediately expire an account's password, you can pass the -e option to passwd command. This in effect can force a user to change his/her password at the user's next login.
Let us assume user name is raj, then login as root user and type following command:
# passwd -e raj
Next time when raj tries to login
You are required to change your password immediately (root enforced)
Changing password for raj
(current) UNIX password:
Enter new UNIX password:
Retype new UNIX password:
Linux debian 2.6.13 #2 Sun Oct 2 20:07:57 IST 2005 i686 GNU/Linux
Last login: Thu Oct 6 01:24:15 2005