How to use access control lists (ACLs) in CentOS systems to restrict access to files and directories

How to use the access control list (ACL) in the CentOS system to restrict access permissions to files and directories

Overview:
In the CentOS system, we can use the access control list (ACL) to more Granular control of file and directory access permissions. It allows us to set specific permissions for specific users or user groups. In this article, we will learn how to use ACLs to restrict file and directory access in CentOS systems and provide some practical code examples.

What is an access control list (ACL)?
Access control list (ACL) is a technology for controlling permissions on the operating system, allowing us to set specific permissions for specific users or user groups in addition to standard user and group permissions. By using ACL, we can control access permissions of files and directories more flexibly.

Note:
Before you start, please make sure that your system has ACL installed and the file system has been mounted with the ACL option. You can use the mount command to confirm whether the file system has been mounted with the ACL option. If it is mounted, you will see an acl option.

Code examples:
The following are some common operations and sample code for using ACLs to restrict file and directory access permissions:

1. Use the setfacl command to Add ACL to a file or directory:

$ setfacl -m u:jdoe:rwx file.txt

The above command will set the read, write, and execute permissions of file.txt to user jdoe.

2. Use the getfacl command to view the ACL information of a file or directory:

$ getfacl file.txt

The above command will display the ACL information of file.txt ACL information, including user and user group permissions.

3. Use the setfacl command to remove the ACL of a file or directory:

$ setfacl -x u:jdoe file.txt

The above command will remove the user jdoe pair ACL permissions for file.txt.

4. Use the setfacl command to set the default ACL:

$ setfacl -d -m u:jdoe:rwx directory

The above command will set the default ACL of the directory directory to the userjdoeRead, write, and execute permissions.

Summary:
By using access control lists (ACLs), we can more finely control access permissions to files and directories. In the CentOS system, we can use the setfacl and getfacl commands to set and view ACL permissions. I hope this article can help you understand and use ACL to improve system security and file access control.

The above is an introduction and sample code on how to use access control lists (ACL) to restrict access permissions to files and directories in CentOS systems. Hope this helps!

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