Mac OS X Tiger in a Nutshell

Exploring root

The root directory of a Mac OS X boot disk has the most to hide, from the Finder’s point of view; it may play root to as many as three separate operating systems’ filesystems, all at once! Beyond holding the lowest-level directories of the Mac OS X filesystem, such as the /System and /Library folders, the root directory also contains the basic directories that Darwin—the pure Unix system running at Mac OS X’s core—needs. These include the directories that any Unix user would recognize, such as /etc and /tmp. Compare Figure 9-3 with Figure 9-4.

Furthermore, if Mac OS 9 is installed on the boot disk, its System Folder appears under the root directory, as do several Mac OS 9 configuration files. Other arbitrary files and folders created by the Mac OS 9 application might also exist at root because that operating system lacks Mac OS X’s permission system and doesn’t view the root directory as “sacred ground.” For example, many Mac OS 9 software installers create new folders directly under root; Mac OS X installers place their software in locations such as /Applications/Library.

Mac OS X’s Finder, when displaying the boot disk’s root folder, will show most of the low-level Mac OS X and Mac OS 9 filesystems’ folders, but keep several special files hidden from sight, and it won’t show any of Darwin’s directories.

Hidden Mac OS 9 files

This isn’t a book about Mac OS 9, so we won’t go into detail about these files’ functions. However, it’s worthwhile to point out their presence ...