WORKING WITH UNIX

This section discusses the process of logging into the UNIX operating system and the prerequisites for the same.
LOGGING IN
The user needs to have a user name for logging into the UNIX operating system and using it.
USER ACCOUNT SETUP
After a UNIX system is booted, the user cannot simply start using it like any PC. Before the user can access the computer system, someone—usually the system administrator—must configure the computer for use.
The user must know two things before he can start using the system: his user name and password. The user name is a unique name that identifies the user to the system. The system administrator, before creating a user name, will verify that no one else on the system has the same name before allowing the new user to have it. The password that has been assigned to the user is a temporary string that allows him to initially access the computer system. The initial password isn't of any real importance because the user should change it to something of his choice the first time he logs in to the system.
Whenever a new user is created by the system administrator or the super user, the following details have to be entered in the /etc/passwd file:
User Name
User’s Password
User_Id
Group_Id
User Description
Home Directory



a /etc/passwd file
LOGGING IN TO THE SYSTEM
Once the system administrator has done the necessary groundwork required for a new user, the new user can log in. The system will prompt (ask) the new user for his user name by printing

Login:
The user should then enter his user name. Next, UNIX will prompt him for his password by printing
Password:
The user should enter his password. As the password is being typed, the user will not be able to see the characters he typed, for obvious security reasons so that no one else can get to know his password by looking at the screen when the user logs in.
If the user types everything correctly and the system administrator has everything set up correctly, the user should be able to log in and use the system. On logging in successfully, the system puts the user on to his home directory, the directory allotted by the super user for the user to work in. If the system displays a message saying Login Incorrect, then the user may have typed his user name or password incorrectly and hence the system rightfully denies access for working.