ipsrlinuxforum.com

Company: Piserve technologies

Date: Thursday, 13th August 2015

Time: 10:00 AM

Designation: Linux System Administrator

Eligibility Criteria: BE/BTech
RHCE

Cut off Percentage: 80% for 10th & Plus Two, 70% for BTech

Experience: Fresher

How do I set or change Linux system password for any user account?

Both Linux and UNIX use the passwd command to change user password. The passwd is used to update a user’s authentication token password stored in shadow file.

The passwd changes passwords for user and group accounts. A normal user may only change the password for his/her own account, the super user or root may change the password for any account. The administrator of a group may change the password for the group. passwd also changes account information, such as the full name of the user, user's login shell, or password expiry date and interval.

Task: Set or Change User Password
Type passwd command as follows to change your own password:
passwd
Output:

Changing password for vivek
current UNIX password:
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfullyThe 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 this step 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 alphabetics
Upper case alphabetics
Digits 0 thru 9
Punctuation marks
Task: Change Password For Other User Account
You must login as root user, type the following command to change password for user vivek:
# passwd vivek
Output:

Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfullyWhere,

vivek - is username or account name.
Task: Change Group Password
When the -g option is used, the password for the named group is changed. In this example, change password for group sales:
# passwd -g sales
The current group password is not prompted for. The -r option is used with the -g option to remove the current password from the named group. This allows group access to all members. The -R option is used with the -g option to restrict the named group for all users.