1.login
Function: Use login allows users to log into the system. If no argument prompted for a user name at login. If the user is not root, and if the contents of the file / etc / nologin file exists is displayed on the screen, the login is terminated
Command syntax: login [options] [username]
Option Meaning:
-h use other server to deliver the name of the remote host to login so that it can be placed in utmp and wtmp
-p login does not destroy the environment
-f used to skip a second login authentication
2.logout
Features: Log shell
Command Syntax: logout
3.nologin
Function: to restrict certain users log into the system by Shell. /Etc/nologin.txt If the file exists, its contents are displayed to the user, instead of the default news
Command syntax: nologin