Five different ways to group user IDs in Linux

"Five different grouping methods of user IDs in Linux"

In the Linux operating system, user ID (User ID) is a number used to identify different users. . The user ID determines the user's permissions and access level in the system. In addition to ordinary users, system administrators can also group users to better manage and control user permissions. In Linux, there are many ways to group user IDs. Five common grouping methods will be introduced below, with specific code examples.

1. Basic User ID grouping method (Primary User ID):

In the Linux system, each user has a basic user ID, also called Primary User ID. This ID is the user's main identification in the system and determines the user's access rights and resource control. You can use the following command to view the basic user ID of the current user:

$ id -u

2. Additional User ID grouping method (Additional User ID):

In addition to the basic user ID, the Linux system also allows users to have Multiple additional user IDs, also known as Additional User IDs. By setting additional user IDs, users can access different resources in different environments. You can use the following command to view all user IDs of the current user (including basic user IDs and additional user IDs):

$ id

3. User group ID grouping method (Group ID):

User group ID (Group ID) is used to divide different users into different user groups to better manage and control user permissions. You can use the following command to view the user groups to which the current user belongs:

$ groups

4. Additional Group ID grouping method (Additional Group ID):

In addition to user group IDs, Linux also allows users to have multiple additional group ID, also known as Additional Group ID. By setting additional group IDs, users can have different permissions in different user groups. You can use the following command to view all group IDs of the current user (including user group IDs and additional group IDs):

$ id -G

5. Special User ID grouping method (Special User ID):

Special User ID (Special User ID) is a user ID that has special permissions when the user accesses the system. Among them, the super user (root) is the most special user and has the highest authority in the system. You can use the following command to check whether the current user is a super user:

$ sudo id

Summary:

The above are five different grouping methods of user IDs in Linux. Each method has its specific role and Applicable scene. By properly setting the grouping method of user IDs, users' permissions and resource access in the system can be better managed and controlled. I hope readers can learn more about Linux user IDs through this article and use them flexibly in practical applications.

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