Mount external USB drive in Single User Mode

How can I mount an external USB drive when I'm in Single User Mode on my Mac?

I'm not able to see it in /dev/

Solution 1:

First, get full access to your boot volume:

fsck -yf
mount -uw /

Then, get kextd and notifyd running to load the needed device drivers and create /dev/ entries:

launchctl load /System/Library/LaunchDaemons/com.apple.notifyd.plist
launchctl load /System/Library/LaunchDaemons/com.apple.kextd.plist
ls /dev/disk*

Then, to mount the volume (assuming the /dev/ entry for it is /dev/disk1s2 and it's HFS/HFS+/HFSX format; adjust as needed...):

mkdir /tmp/usbvolume
mount_hfs /dev/disk1s2 /tmp/usbvolume

Edit: at least under 10.6.4, loading notifyd and configd seems to prevent the system from shutting down normally (i.e. the reboot command will hang). Loading configd and diskarbitrationd (using launchctl load ... as above) as well allows it to shut down normally.

Edit2: unloading kextd (launchctl unload ...) also allows shutdown (but you should probably wait 'till you're about to shut down).