Introduction to Linux User management

Linux User Management is one of the good features of Linux, this article explains the login process of Linux users and the type of logged-in users.

One, the Linux user logon process

To use a Linux system, users must log in first. The logon process for Linux is similar to the logon process for Windows, and user logons include the following steps:

1. When the Linux system is booted properly, the system can accept the user's login. This is the user terminal display login： prompt, if it is a graphical interface, the user Login window will be displayed, then you can enter the user name and password.

2. After the user enters the user name, the system checks to see if the/etc/passwd has the user, or exits if it does not exist, and then proceed to the next step.

3. The user ID and the group ID in the/etc/passwd are read first, and other information from the account (such as the user's home directory) is also read.

4. After the user enters the password, the system checks the/etc/shadow to determine if the password is correct. If the password verification passes, then enters the system and starts the system shell, the system startup shell type is determined by the information in the/etc/passwd. Linux can be manipulated through a system-provided shell interface.

Ii. Types of Linux users

Linux user types are divided into 3 categories: Superuser, System user, and normal user.

1. Superuser: An account with a username of root or user ID (UID) of 0, with all permissions, all resources available in the operating system. Root can be used for basic file operation and special file management, in addition to network management, you can modify any file on the system. You should avoid using such accounts in your daily work and use the root login system only when necessary.

2. System User: The account used to run the system normally. Each process runs in the system with a corresponding owner, such as the identity of a process running, which is the corresponding user account in the system. Note that the system account cannot be used to log in, such as bin, daemon, mail, etc.

3. Ordinary User: Ordinary users, can use most of the Linux resources, some specific permissions are controlled. Users only have write permission to their own directory, read and write permissions are limited, thereby effectively ensuring the Linux system security, most of the users belong to this category.

Introduction to Linux User management