What are the linux user groups?

In Linux, a user group is a logical collection of users with the same characteristics; a user group is a means for the system to uniformly manage objects of the same type. Users of the same type are put into a group to encapsulate them into one For a larger whole, using user groups helps organize and manage users according to their characteristics.

#The operating environment of this tutorial: linux7.3 system, Dell G3 computer.

What is the user group of Linux

Linux is a multi-user, multi-tasking time-sharing operating system. If you want to use system resources, you must apply for an account from the system administrator, and then use this The account enters the system. This account and user are the same concept. By establishing users with different attributes, on the one hand, system resources can be reasonably utilized and controlled. On the other hand, it can also help users organize files and provide security protection for user files.

Each user uses a unique username and password. When logging in to the system, only if the username and password are entered correctly can the system and their own home directory be entered.

A user group is a logical collection of users with the same characteristics. Sometimes we need to allow multiple users to have the same permissions.

For example, to view and modify the permissions of a certain file, one way is to authorize file access to multiple users respectively. If there are 10 users, they need to authorize 10 times. Obviously this method is not reasonable. .

Another method is to create a group, let this group have the permission to view and modify this file, and then put all users who need to access this file into this group, then all users will have the permissions and group Same permissions. This is the user group. Grouping users is a means of managing users and controlling access rights in the Linux system. By defining user groups, management work is simplified to a great extent.

To put it bluntly, user groups are a technical means for unified management of the same type of objects in Linux. They put the same type of users into a group and encapsulate them into a larger whole;

It's like encapsulating the same type of students into a class, the students are the users, and the class is the group; operating on the class is actually operating on all students in the class;

1.4 Relationship between users and groups

The corresponding relationships between users and user groups are: one-to-one, one-to-many, many-to-one and many-to-many; the following figure shows this relationship:

One-to-one : That is, a user can exist in a group or be the only member of the group.

One-to-many: that is, one user can exist in multiple user groups. Then this user has common permissions for multiple groups.

Many-to-one: Multiple users can exist in a group, and these users have the same permissions as the group.

Many-to-many: Multiple users can exist in multiple groups. In fact, it is an expansion of the above three corresponding relationships.

1.5 The impact of users and groups on linux

Suppose we now have several users: zwm, sjg, wxh

Suppose zwm and sjg The user is the g1 group, wxh is the g2 group

We used the zwm user to create a file file1

Then for this file1, there are three permission settings

1 . User --> File owner Full permissions Read Write Execute 4 2 1 = 7

The user (zwm) who directly created this file has very high permissions on this file

2 . Group --> File owner same group permissions Read

The group this user belongs to (g1 group), what kind of operation permissions do users in the same group as the above user have on this file

3. Others --> In addition to the file owner and owner group, those users (wxh) who use 0

, what do other people except the above user and the above group have on this file? Permission operation

Related recommendations: "Linux Video Tutorial"

The above is the detailed content of What are the linux user groups?. For more information, please follow other related articles on the PHP Chinese website!