passwd command is used in Linux and UNIX to change user password.
The passwd is used to update a user authentication token (password) stored in shadow file.
The passwd changes passwords for user and group accounts.
Super user (or root) can change the password for any user account where as A normal user can change the password for his/her own account.
The administrator of a group may change the password for the group.
With passwd command we can change the account information’s of an user. Such as User’s full name, User’s login shell, User’s password, User’s expiry date.
Q. Set or Change User Password
Type passwd command to change the user password:
Changing password for User Rajeev
(current) UNIX password: XXXXXX
Enter new UNIX password: XXXXXX
Retype new UNIX password: XXXXXX
passwd: password updated successfully
The user is first prompted for his/her old password, if one is present. This password is then encrypted and compared against the stored password. The user has only one chance to enter the correct password.
The super user is permitted to bypass above steps so that forgotten passwords may be changed.
A new password is tested for complexity. As a general guideline, passwords should consist of 6 to 8 characters including one or more from each of following sets:
Lower case alphabetic, Upper case alphabetic, Digits 0 thru 9 and Punctuation marks