User Login Process

When the user is trying to logging into system then Kernel should know who is that user.

Kernel manage this user logging process by running below programs

1. getty    
2. loging 

       [getty is short for “get terminal”.]

• Kernel calls program ‘init’. ‘init’ calls program ‘getty’, which issues a login prompt in the monitor.

• User enters login and password.‘getty’ calls program ‘login’ which scans file /etc/passwd to match username and password. 

• After validation, control passes to session startup program /bin/sh .User gets a shell prompt. 

• If the user fails to provide valid password, the login program returns the control back to the getty program.