Linux user login

Linux is a truly multi-user operating system. To use the system, users must first log in. After using the system, they must log out. When the user logs in to the system, in order for the system to recognize the user, the user name and password must be entered, and the system can be used to log in to the system after being verified by the system. There are two kinds of users under Linux: 1) root user: super privilege, system owner, there is only one root user in the Linux system, it can operate in the system. The password set during system installation is the password of the root user. 2) Ordinary users: Linux systems can create many ordinary users and assign them the appropriate permissions to make limited use of Linux systems. Regarding the management of the user, we will explain in detail later. The user login is performed in two steps: 1) Enter the login name of the user, and the system identifies the user according to the login name; 2) Enter the password of the user, which is a string selected by the user, completely confidential to other users, is a login The system only recognizes the user's unique basis, so each user should protect their password! At the beginning of the system, only the root user was created, and other users were created by the root user. Because the root user's permissions are too large, if the root user misuses, it may cause a lot of damage. Therefore, it is recommended that the system administrator create a new user for himself. Only when you need to perform system maintenance and management tasks, log in as the root user. Here is a login example: (where the boldface is the input) Red Hat Linux release 7.1 (Seawolf) Kernerl 2.4.2-2 on an i686 Home login:root Password: In the above example, we found that the password is empty after the password In fact, it is not without entering a password, but when inputting, the Linux system will not display it, so as to protect the password! If the login is successful, we will get the Shell (Shell is a program used to interact with the user, it is like COMMAND.COM in DOS, but there are many shells available for selection under Linux, such as bash, csh, ksh, etc.) At the prompt, if you log in as the root user, the prompt obtained is “#”, otherwise it will be “$”. Tip: If you enter the graphical interface at the time of installation, the user login screen will be graphical, like Windows, and when you enter the correct username and password, it will be directly Enter the X Window. This setting can be modified: There is an inittab file in the /etc directory, which has a line configuration: id:3:default where the number 3 is a boot into the character terminal, if it is changed to 5, it represents a boot into the X Window .