SingleUserMode
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"Utility of last resort" AppleJack updated for Leopard compatibility
You may sincerely wish never to need it, but if you run into a situation where your Mac refuses to boot fully to the Finder and you don't have any boot-capable utilities to tackle the problem, Kristofer Widholm's AppleJack is probably your best friend in the trenches. The single-user-mode tool is only available if you start your machine while holding down Cmd-S to boot to the command line (as per Dave's tip from yesterday), but once there it streamlines the process of checking your disk for errors, repairing permissions, cleaning caches, zapping corrupt preference files, and deleting leftover virtual memory swap data. You could do most of this yourself via a series of commands, but AppleJack is a) much, much simpler and b) completely free and open source.For a long while it didn't look as though AppleJack would make the leap from Tiger to Leopard, as Mac OS X 10.5 made some key changes that broke AppleJack's functionality (specifically, the 'id' command didn't work, and the /etc/rc file was removed). Developer Steve Anthony jumped into the project this summer and was able to code around the Leopard-specific problems, finally giving us back our beloved AppleJack in version 1.5. Let's all raise a glass of the original Jersey Lightning to Kristofer and Steve for their work on behalf of Mac troubleshooters everywhere.
iPhone Tales of Woe: Booting to Single User
A short while back, Digg hosted a link to this crashed iPhone showing single user mode. In that case, the error message stated that the iPhone couldn't "exec /bin/sh for single user: No such file or directory." Now that the iPhone has been thoroughly hacked, this error has evolved somewhat. Last night, TUAW friend DrunkDwarf crashed his iPhone but since he'd actually installed a copy of /bin/sh his error was somewhat different. Instead of complaining that it couldn't find /bin/sh, his iPhone simply... ran it. Not that this was much better news. Without a keyboard and no way to attach one, DrunkDwarf was a bit out of luck. He ended up having to do a restore.
AppleJack 1.4.3rc3 adds Intel support
AppleJack, the wildly popular open source, single user mode troubleshooting tool for Macs, has finally been updated to support Intel-based Macs. Version 1.4.3rc3, a release candidate, is downloadable now on sourceforge and the final version is expected within the week.Besides Intel compatibility, the following tweaks have been made to the new version: Added an automated uninstaller routine, to enable easy and almost foolproof uninstallation of AppleJack. Added /var/root/Library/Caches to the system cache cleanup routine. Experimental expert mode exists, but is currently hidden until it can be tested further. (see Appendix B of the Read Me). The only well-tested options at this point are the memory test using the included Memtest utility, and the option to disable auto login. Improved the internal coding of user-input prompts. Uses a standardized interface for these functions now. The preference file check now uses a null byte character to separate files rather than an arbitrary "improbable" string. I'm just giddy about this. Integrating Memtest is a nice bonus since I use it all the time. Instead of launching Rember, which is a graphical interface for Memtest (proving my command-line phobia once again), I can just add it to my AppleJack routine. Thanks, Apotek, for your continued development of the troubleshooting tool I use the most!
