1. User Access and User ID Commands in UNIX

2. Introduction
UNIX is a multiuser system, means more than one user can work on the UNIX machine at a time. Every user has his own user login and password. User access and id commands include command through which user can
Login into his account
Logout of his account
Change his login account password

3. Logging in the System
To login into the system user enters his login and password which is asked at the starting up of the system
LOGIN:
PASSWORD:
The super user login is root
Every user has a login password
If any of these goes wrong system says login wrong and user has to enter both the entries again

4. Logging out of the System
To logout of his login account user uses the command logout Or Ctrl + d Or types exit * Only user’s login account is closed but the system is still running

5. Changing password To change his login password user uses the command
passwd
enter old password:
enter new password:
reconfirm new password:
User can change password for his login account only
Super user can change password for other users also by using command
passwd user_login_name and the system will ask for the new password and then reconfirm it.
Even the superuser does not what users passwd is