AppleJack

Why do we like Macs? “We just do.” Also, they rarely breakdown. But if you experience disk trouble, AppleJack can help. It’s the Mac freeware we hope you never have to use.

Once installed, AppleJack is accessible from the Single-User Mode command prompt. (Hold down Apple-S while booting.) AppleJack can repair your startup volume, repair permissions, cleanup cache files, and validate preference files. It has a simple text menu so you don’t have to remember commands.

Also see the Macfixit article on AppleJack and read the cautions.

This could be a life saver in case of trouble.

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