File Permissions#
Linux file systems allow a simple permission scheme for each file. There are only three coarse types of file access defined and each can be granted or denied for three types of (user) classes. Moreover there are three special permissions to be granted, but these are only relevant for file execution. In total each file has \(3 \times 3\) matrix (9 bits) of basic permissions.
However there are ways to extend this very basic permission scheme using access control lists.