How do I change password under Redhat Enterprise Linux?

You need to use the passwd command to update a user’s authentication token(s) i.e. password. When you change your own password or other users password, remember the following two principles:

1. Don’t write down your password – memorize it. In particular, don’t write it down and leave it anywhere, and don’t place it in an unencrypted file! Use unrelated passwords for systems controlled by different organizations.
2. Don’t give or share your password, in particular to someone claiming to be from computer support or a vendor.
3. Don’t let anyone watch you enter your password.
4. Don’t enter your password to a computer you don’t trust or if things Use the password for a limited time and change it periodically.
5. Choose a hard-to-guess password.

The passwd command will try to prevent you from choosing a really bad password, but it isn’t foolproof; create your password wisely.

Example

To change your own password, enter:
$ passwd
To change other users password, you must login as root:
# passwd userName
# passwd vivek
To lock user account, enter (must be root user to type the following):
# passwd -l username
To unlock the account password, enter:
# passwd -u username