In order to login to a system a user has to authenticate with his/her credentials:
user name and password.
local (password/shadow/group) and
For local authentication, a user should have an account on the system.
Domain based (NIS, Kerberos, LDAP).
Entry in /etc/passwd:
Entry in /etc/shadow:
Entry in /etc/group:
Accounts can be created only by a superuser (root).
Commands to create user accounts:
adduser (interactive command)
useradd (can be included in a script).
Create a new user account by following the instructor.
Create a new user account, mike
Verify the account existence:
Change password of the user
Reference: User accounts and Ownerships