Lesson 5. Permissions

Mac OS X is designed as a multiuser operating system, with a number of features that help multiple users work on the same computer while maintaining unique files and settings. In fact, with fast user switching and remote login, you can even have more than one user logged in simultaneously. In Mac OS X, to ensure internal security on your computer, the file system uses permissions to limit access.

Imagine that your computer is a set of filing cabinets in an office with a private filing cabinet for each employee. Each employee's private cabinet is locked, unless they specifically grant different access to drawers inside their cabinet. Each employee's private cabinet can have a public in box where coworkers can leave files and a public out box where coworkers can take files. An open "shared" cabinet that anyone can access is available to place files everyone can use.

There are three categories of users for each filing cabinet:

• The owner

• Group members and guests who have access to one or more drawers inside the cabinet

• Others who have access to the in box and out box, but no access to the owner's drawers

You use these categories to define permissions, such as Read & Write access, Read Only access, or No Access.

In this lesson you will learn about file access and permissions issues. The topics will include theoretical and practical information about the Mac OS X user-based permissions model, some examples of permissions in context, and how to troubleshoot file permissions issues.