Permissions are one of several good features that make Linux more secure when applied properly. Since Linux is a multi-user OS, different users will be working with multiple programs and files, and so on. Permissions help keep things secure and organized. In this chapter, you will learn how to manage access controls on files using basic read, write, and execute permissions and user or group ownership. You will also learn to apply special permissions and the access control list (ACL).

In this chapter, we will cover the following topics:

• Understanding Linux filesystem permissions
• Managing file permissions 
• Managing file ownership
• Special permissions
• Managing default permissions
• Managing ACL on files