Library
From Mac Guides
The Library in Mac OS X is a special folder in which many system and applications resources are stored. There are separate Library folders for each file-system domain; the system domain, the local domain (resources shared by all users) and the user domain.
Contents |
Libraries
System Library
The System Library, located at /System/Library/, stores the operating system. It is read only, to protect the system (although changes can be made by superusers), and so does not store any preferences files like other Library folders.
Notable items inside the System Library include:
- Menu Extras- If you navigate to /System/Library/CoreServices/Menu Extras/, you can see a full list of menu extras. Open one to add it to your menu bar.
- The Dock is located at /System/Library/CoreServices/Dock. If you control-click on it and choose "Show Package Contents", then navigate to Contents/Resources/, you will find several interesting files. The "Widgets" Dashboard widget, introduced in Mac OS X 10.4.2, is located here, as well as the Dock's "poof" animation (stored in poof.png), which can be replaced by an alternative animation provided you have an image with suitable dimensions (these can be found on various websites) and superuser privileges.
- The Tiger introduction movie, shown when the operating system is first booted, can be found in two separate files, intro-sound.mp3 and intro.mov, both located in
/System/Library/CoreServices/Setup Assistant/Contents/Resources/TransitionSection.bundle/Contents/Resources/
Local Library
The local Library (located at /Library/) is shared by all users on the system and stores a variety of resources. These include preferences for System processes, desktop pictures, dictionaries (for Tiger), receipts (used for repairing permissions, system logs, caches and more. It can also store Dashboard widgets, screen savers and other resources shared by all users.
User Library
The user Library (located at ~/Library/) is the one which you are most likely to need to be familiar with. It is the most frequently updated, as it stores application preferences, application support files, caches and much more. If you encounter problems with applications, a common source is a corrupt file in your user's Library folder. For more information about troubleshooting these problems, see the article on troubleshooting software problems.
Subdirectories
Each Library folder has a number of subdirectories. The following table lists some of these subdirectories, with a brief description and whether each Library folder can include it.
| Subdirectory | Description | User | Local | System |
|---|---|---|---|---|
| Application Support | Application specific support files such as plug-ins and helper applications. This is only used by some applications. Each application that uses this folder has its own subdirectory. | Yes | Yes | No |
| Audio | Audio plug-ins and device drivers. | Yes | Yes | No |
| Caches | Cached data to speed up future operations. | Yes | Yes | Yes |
| Audio | Audio plug-ins and device drivers. | Yes | Yes | No |
| Components | System bundles and extensions. | No | Yes | Yes |
| CoreServices | Essential system files. | No | No | Yes |
| Documentation | Documentation files intended for users and administrators. Not much useful data is contained in these, as most help files are stored in other places. | No | Yes | Yes |
| Extensions | Device drivers and other kernel extensions. | No | No | Yes |
| Fonts | Font files for display and printing. | Yes | Yes | Yes |
| Frameworks | Frameworks and shared libraries. | Yes | Yes | Yes |
| Logs | Log files for the system and applications, viewable with the Console application. Crash reports are stored here, which can be sent to Apple or application developers in order to fix bugs. | Yes | Yes | No |
| Your email stored in Mail. | Yes | No | No | |
| PreferencePanes | Plug-ins from System Preferences, also known as preference panes. | Yes | Yes | Yes |
| Preferences | Application settings. | Yes | Yes | No |
| Printers | Printer drivers (for system and local domains) or printer configurations (for the user domain). | Yes | Yes | Yes |
| QuickTime | QuickTime components and extensions. | Yes | Yes | Yes |
| Receipts | Information about application and system installations. Used for repairing permissions. | No | Yes | No |
| Screen Savers | Screen Savers used in the Desktop & Screen Saver preference pane. | Yes | Yes | Yes |
| Scripts | AppleScript scripts. | Yes | Yes | No |
| Sounds | System alert sounds. | Yes | Yes | Yes |
| StartupItems | System and third-party processes to be run at boot time. You should not modify this folder yourself, use the Accounts preference pane to setup applications to startup when you log in. | No | Yes | Yes |
| Widgets | Dashboard Widgets. | Yes | Yes | Yes |
Links
The Library Directory (Apple Developer Connection Documentation)
