Mac OS X: The Missing Manual, Second Edition

Fixing the Disk

As noted in the introduction of this book, the beauty of Mac OS X’s design is that the operating system itself is frozen in its perfect, pristine state, impervious to conflicting system extensions, clueless Mac users, and other sources of disaster.

That’s the theory, anyway. But what happens if something goes wrong with the complex software that operates the hard drive itself?

Fortunately, Mac OS X comes with its own disk-repair program. In the familiar Mac universe of icons and menus, it takes the form of a program in Applications→Utilities called Disk Utility. In the barren world of Terminal and the command line interface, there’s a utility that works just as well but bears a different name: fsck (for file system check).

In any case, running Disk Utility or its alter ego fsck is a powerful and useful troubleshooting tool that can cure all kinds of strange ills, including these problems, among others:

• Your Mac freezes during startup, either before or after the Login screen.

• The startup process interrupts itself with the appearance of the text-only command line.

• You get the “applications showing up as folders” problem (see Section B.9).

Method 1: Disk Utility

The easiest way to check your disk is to use the Disk Utility program. Use this method if your Mac can, indeed, start up. (See Method 2 if you can’t even get that far.)

Disk Utility can’t check the disk it’s on. That’s why you have to restart the computer from the Mac OS X CD-ROM (or another startup disk), and run Disk ...