Phase-1
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1. Tree structure of command hierarchy.
2. Unix user authentication.
3. Normal user belonging to opennop group can also log into to CLI.
4. Privilege based command execution.
5. In case user is logged in with su <other_user> then check the group credentials of new user and use it accordinly, in case if the new user
	is not the part of opennop group , then we ask for login .
6. It should have option of login with two ways, opennop and opennop -l <login_name> -p <password>
