User Classes

For each file, there are three classes of users that specify the levels of security:

• The file or directory owner--usually the user who created the file. The owner of a file can decide who has the right to read it, to write to it (make changes to it), or, if it is a command, to execute it.

• Members of a group.

• All others who are not the file or group owner.

Only the owner of the file or root can assign or modify file permissions.