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2006年04月09日

Command Shell from OS X Install CD

I have been trying to help my friend Paige recover her Mac that died after an attempted upgrade to OS X version 10.4.6. In Linux, I often boot to single user mode to troubleshoot hairy problems. In OS X, this can be achieved by holding down Apple-S. (The "Apple" key is really called the "command" key, so the shortcut is usually abbreviated to cmd-s). Magical Macintosh Key Sequences is a good reference for keyboard shortcuts.

Unfortunately, the system would still hang (apparently at launchd) when booting to single user mode with the message:

 Load of /sbin/launchd, errno 88, trying /sbin/mach_init
 Load of /sbin/launchd failed, errno 88

It seems perhaps an important part of the filesystem is screwed up. I ran the disk repair utility included on a borrowed OS X installation CD. Well, we would have tried a re-install but unfortunately the installer only applies to a couple of Powerbook models and not the one Paige has. It refuses to install, but still boots and lets you run the utilities.

The repair utility fixed some errors, but will not fix the error it describes as:

 Invalid leaf record count
 (It should be 9 instead of 2923)

If I were using Linux, I would boot to a command shell using the (kernel image on the) install CD to explore further options. However, the OS X install CD in all its glorious user friendliness would not dare suggest the user venture to the dark territories of the fearsome OS X Shell. There is no "boot to command prompt" option in the menu and google would not tell me how to acheive this either.

So extensive research on the boot process and Open Firmware led me to this idea to boot to a command prompt from the CD:

• Boot to an Open Firmware prompt by powering on with cmd-opt-o-f.
• Set the boot device to the cd with the command setenv boot-device cd:,\\:tbxi
• Skip the gui and go straight to the prompt by setting the boot arguments to specify single user mode setenv boot-args -s
• Boot the mac with the command mac-boot
• (If you get a memory allocation error, type reset-all to restart and it will boot straight to the command shell off the CD)

If you follow those directions, you should get to a shell prompt and be able to muck around. Enjoy! Whether or not I can use it to solve the main problem remains to be seen. =/

Posted by William at 2006年04月09日 03:13

Comments

Posted by: Taizo at 2006年04月09日 14:50

Posted by: Jason at 2006年04月10日 01:58