The owner and group attributes

Each file on the system has an owner. Generally, the creator of the file is also the owner. However, a file owner can generally reassign ownership rights using the chown(C) command.

If you own a file, you can decide who has the right to read it, write to it, or, if it is a program, to execute it. You can also restrict permissions for directories. When you grant execute permission for a directory, you allow the specified users to change directory to it and list its contents with the ls(C) command. Only the owner or a privileged user can define the following:

• which users have permission to access data

• which types of permission they have (that is, how they are allowed to use the data)

Each file is also assigned to a particular group. A group is a collection of users. Each user may be assigned to one or more groups. The users in a file's group may have special DAC permissions set.