What Are Linux File Permissions?
Setuid, Setgid and Sticky Bits are special types of Unix/Linux file permission sets that permit certain users to run specific programs with elevated privileges. Ultimately the permissions that are set on a file determine what users can read, write or execute the file. Linux provides more advanced file permissions that allow you to do more specific things with a file, or directory. Typically, these file permissions are used to allow a user to do certain tasks with elevated privileges (allow them to do things they normally are not permitted to do). This is accomplished with three distinct permission settings. They are setuid, setgid, and the sticky bit.