How to use Linux for user and permission management

How to use Linux for user and permission management

Introduction:
In the Linux operating system, user and permission management is a very important part. Properly managing users and permissions can ensure the security and stability of the system. This article will introduce how to use Linux for user and permission management, and attach some code examples for reference.

1. Create a user
To create a user in Linux, you can use the useradd command. The following is sample code to create a user named user1:

sudo useradd user1

This command creates a new user user1. If you want to create the user's home directory at the same time, you can use the -m option:

sudo useradd -m user1

In addition, you can also set the default shell for the user, for example, set the user's default shell to bash:

sudo useradd -m -s /bin/bash user1

When creating a user, you can also set the user's password, which is achieved through the passwd command:

sudo passwd user1

After executing the above command, the system will ask for input Enter the password twice to confirm the password.

2. Delete users
To delete users in Linux, you can use the userdel command. The following is a sample code to delete user user1:

sudo userdel user1

This command will delete user user1. If the user's home directory needs to be deleted at the same time, you can use -rOption:

sudo userdel -r user1

After executing the above command, the user and the user's home directory will be completely deleted.

3. Modify users
In Linux, you can modify user attributes through the usermod command. The following is a sample code to modify the default shell of user user1 to bash:

sudo usermod -s /bin/bash user1

This command will modify the default shell of user user1 to bash.

4. User Group Management
In Linux, users can belong to one or more user groups. User group management can be achieved through commands such as groupadd, groupdel, and groupmod.

1. Create user group
   The following is a sample code to create a user group named group1:

   sudo groupadd group1

   This command creates A user group named group1.

2. Delete user group
   The following is a sample code to delete user group group1:

   sudo groupdel group1

   This command will delete user group group1 is deleted from the system.

3. Modify user group
   The following is a sample code to add user user1 to user group group1:

   sudo usermod -a -G group1 user1

   This command adds user user1 to user group group1.

5. Permission management
In Linux, the permissions of files and directories are determined by the user (owner), user group (group) and other users (others). There are three permissions: read (r), write (w) and execute (x).

1. Modify permissions
   The following is a sample code to set the owner user permissions of file file1 to read-only:

   chmod u=r file1

   This The command sets the owner user permissions of file file1 to read-only.

2. Modify user group permissions
   The following is a sample code to set the user group permissions of file file1 to read and write:

   chmod g=rw file1

   This This command sets the user group permissions of file file1 to read and write.

3. Modify other user permissions
   The following is a sample code to set other user permissions of file file1 to execution:

   chmod o=x file1

   This The command sets other user permissions for file file1 to execute.

6. Summary
Through this article we have learned how to use Linux for user and permission management. We learned how to create users, delete users, modify user attributes, as well as user group management and permission management. Proper use of these commands can improve system security and stability.

Reference:

1. Linux Commands - useradd(8) Manual Page.
2. Linux Commands - userdel(8) Manual Page.
3. Linux Commands - usermod(8) Manual Page.
4. Linux Commands - groupadd(8) Manual Page.
5. Linux Commands - groupdel(8) Manual Page.
6. Linux Commands - groupmod(8) Manual Page.
7. Linux Commands - chmod(1) Manual Page.

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