Introduction to the File System Overview

Conceptual information and guidelines describing the structure and usage of the Mac OS X file system.

Organization of This Document

The Mac OS X File System contains the following articles:

File-System Domains describes the high-level organization of the file system in Mac OS X.
The Library Directory describes the standard subdirectories that are used to configure the system and user environments.
The Developer Directory describes the developer-specific directories that are installed with the Xcode Tools.
Where to Put Application Files provides guidelines on where applications should place non-essential configuration and support files.
Files and the Finder describes the role of the Finder in managing the file system. It also explains some of the techniques the Finder uses to associate files with applications.
Sorting Rules explains the rules for ordering file and directory names in Finder windows.
File System Guidelines offers tips and advice on how best to support Mac OS X file system features.
Filename Extensions describes the Mac OS X support for filename extensions and how to support them in your applications.
Display Names explains the difference between file names in the file system and the file names that users see. It also explains when your application should use display names.
BSD Permissions and Ownership describes the principles behind file permissions and their implications for file management in Mac OS X.
Access Control Lists provides an overview of access control lists and how they are used to supplement BSD permissions.
File System Comparisons offers a comparison of features between HFS+ and UFS volume formats.
Aliases and Symbolic Links describes the differences between aliases and symbolic links.