I'm trying to repair my sister's iMac using single-user mode.

Since a recent power outage (no surge protector) it won't boot. I used verbose mode to see where it was hanging ("mDNSResponder: adding browse domain local") and found some advice online that said repairing the disk permissions might help.

So I booted into single user mode, ran fsck -fy a couple times until it stopped complaining, ran mount -uw / and autodiskmount -va fine, and got stuck at diskutil.

It just hangs (over an hour, no output).

Is there anything else I should try, or should I just revert to surgery and grab the hd?

2 Answers 2


Sounds like your filesystem took a serious beating (if you have to run fsck multiple times, it probably discarded a bunch of stuff in the process). Permission repair (diskutil repairPermissions disk<X>s<Y>) relies on the package receipts kept in /var/db/receipts and will not work successfully if these are damaged or missing (although it shouldn't hang, but who knows what else got blown up).

Assuming you don't have a recent backup of the system (if you do, restore from that), the next step would be to boot from the OS X DVD, launch Disk Utility from there and try it's permission repair. If that doesn't work either, exit Disk Utility and select Archive & Install, which basically moves all system files into /Previous System, reinstalls OS X and leaves the user files intact (or at least as intact as they are now). If you lack the disk space for that, you can also Install (without archiving the old system files). In either case you'll want to check the Preserve existing Users & Network Settings option.

  • I opted for surgery, but if I'd had an install disk to work with, I would have wanted to give this a shot.
    – rampion
    Aug 30, 2011 at 20:24

Diskutil won't start in single-user mode without starting the following five services first:

notifyd, configd, diskmanagementd, securityd and disarbitrationd.

Details and example-script here: http://www.system-fabrik.de/diskutil-single-user-mode/

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