Unix Third Edition: Visual Quickstart Guide

Understanding File Ownership and Permissions

Unix provides three levels of file ownership:

• User. Refers to the single userid that’s primarily in charge of the file. You have this level of ownership for the files you create.

• Group. Refers to the group (of users) associated with a specific file. All users within a group have the same permissions for interacting with a file.

• Other. Refers to any users not identified with either the group or user for a file.

Within these groups, you can specify permissions for file access and rights in three categories:

• Read. Users with read permission can only view a file; they cannot make changes to it.

• Write. Users with write permission can make changes to or delete a file.

• Execute. Users with execute permission ...