9.1 "Linux learning is not difficult" user management ( 1 ): Linux user account classification
User accounts are divided into roles in the Linux system. Due to different roles, each user has different permissions and tasks that can be performed. In actual management, a user's role is identified by a UID (user ID number), and each user's UID is different. There are three types of users in Linux system, namely root user, system user and ordinary user.
1 . root user
In the Linux system, the root user UID is 0 , the root user has the highest authority, and the root user can perform operations that cannot be performed by ordinary users, so it is also called a super user. Every file, directory and process in the Linux system belongs to a certain user. Without user permission, other ordinary users cannot operate, except for the root user. The privilege of the root user is also reflected in the fact that the root user can read, modify and delete files or directories beyond any user and group (within the normal permission scope of the system); can control the execution and termination of executable programs; can Perform operations such as adding, creating and removing hardware devices; you can also modify the attributes and permissions of files and directories to suit the needs of system management.
2 . system user
System users are also called virtual users, pseudo users or fake users. Such users do not have the ability to log in to the Linux system, but are indispensable users for system operation, such as bin , daemon , adm , ftp , mail , etc. Users are owned by the system itself. The UID of the system user is 1~999 .
3 . general user
Ordinary users can log in to the system, perform common operations on the Linux system, and operate the contents of their own directories. Their permissions to use the system are limited. These users are created by the system administrator, and their UIDs are between 1000 and 60000 .
Notice:
In different versions of Linux systems, the UID ranges are different when creating system users and ordinary users .
This article is excerpted from the textbook " Linux Learning Is Not Difficult" , which is the most practical and practical Linux introductory textbook. To read the entire book, please visit Linux Operators ( www.linuxywz.com) website .