I have been given a Mac to repair after a failed update, and may not be able to get reliable information about which update was being applied, or, indeed, to which operating system. If the system would boot, it'd be obvious which OS it was running, and could easily be confirmed by running sw_vers or going to "About This Mac".

How can I determine which version of OS X this box has on it, by looking at the filesystem in target disk mode?


man sw_vers | tail shows you the file you need to look at, namely:


When you cat those files, you learn what you need to know.


I'm hoping it boots with the hardware but that the software is the only thing that's fubared...in that case you should find some hints if you boot the system in Firewire Target Disk Mode and browse the files for a version. You might find a text string in something in the configuration file /System/Library/Coreservices/SystemVersion.plist.

MacTracker is a free program that can also list the default OS that came with various Macs, if you absolutely have to fall back to what it was last supporting. It's a wonderful reference for everything from types of RAM systems use to what ports they have and can support; it should list the minimum (and maximum) OS X versions your Mac supports.

  • I believe the hardware is is fine, and that the system is just in an inconsistent state from an interrupted software updated. The hardware boots fine, and the system boots through a couple of screens but doesn't get to the login window. Booting in verbose mode didn't make the problem obvious, and I never actually checked if I could log in in single-user mode. – Clinton Blackmore Aug 16 '09 at 5:19
  • I've had this happen to me on a MacBook...if you know the update that went awry, you can download the combo updater, boot to target disk mode, and run the updater then point the update to the firewire disk (unbootable computer). I managed to fix my system doing that from a second MacBook. The combo updater apparently overwrote and completed the previous update's failed attempt. – Bart Silverstrim Aug 16 '09 at 12:40
  • That's funny. It is exactly what I did -- applied the latest combo update for that OS. [I'm not sure that it was the update that had failed]. I've had this restore computers, and I've had it fail. This time it failed :( So, I images the HDD, will re-install the OS, and migrate the user data back from the disk image. – Clinton Blackmore Aug 16 '09 at 15:35

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