DAC is also known as user-dictated access control. You may already be familiar with the classic permissions in Linux and ACLs. These combine to form DAC. Classic permissions check the user ID (UID) and group ID (GID) of the current process. Classic permissions match the UID and GID of the user trying to access the file with the UID and GID set to the file. Let's see how DAC was introduced and what level of permission you have in Linux. However, we will not be discussing this in detail as the main intention is to get you familiarized with permissions in Linux.

Introduction to DAC

The majority of operating systems, such as Linux, macOS, flavors of Unix, and even Windows, are based on DAC. MAC and DAC were defined in the Trusted Computer System Evaluation Criteria (TCSEC), also known as the Orange Book, published by the US DoD (Department of Defense). We'll be discussing MAC in the next section. As the name suggests, DAC allows the owners or creators of files to decide...