You need to read the help while in rdshell. For some obscure reason, there doesn't seem to be a man page, at least on the first page of googling, and that after trying a man on it. Try looking at http://tuxers.com/main/instigating-a-manual-boot-from-the-grub-prompt/ Yes, I know he's ubuntu, but down here, there's not much difference. The tab is *very* useful, since it will try autocomplete.
Hope this helps some.
mark
Ok - so I am looking at the GRUB stuff, I boot up, hit c for command type ls and I get "unrecognized command". Not off to a good start...
Hit TAB and sure enough ls is not listed there. Perhaps that is part of grub2?
Anyway still looking... Thanks
Jerry