RescueCD - what is this for?

[David Timms]

Timothy Murphy wrote:
> so I burned a Fedora-7 rescueCD and tried that,
> but it seems I was then supposed to insert the system DVD.
> 
> Actually, this machine didn't have a DVD reader, so that was out.
> But it left me wondering what the purpose of the Rescue CD is?
The rescue CD has the boot loader, and the stage2 installer taking only 
about 100MB.
The disk is actually multiuse:
- use it to start an install from network or hard disk
- use it to fix a broken system.
It uses the same kernel / boot that the dvd-iso would use to boot your 
system, and hence your system can be trashed but you can still get 
access to it to make fixes.

I forget how you get it to the rescue environment, but it is something like:
- edit the cd's boot command to be: linux rescue, hit enter
- wait for anaconda to load in rescue mode.
- answer Q on keyboard.
- answer question do you want to activate network and so-on
- environment tries to find the installed fedora system on the hard disk.
- answer mount|read only| dont mount
- if you mount it you can:
   - vi /mnt/sysimage/etc/whatever to fix your problem
   - ls -l /mnt/sysimage/etc/whatev*
   - if there's a backup of the corrupted file, mv / replace it.

> I had assumed it was a Knoppix-like CD, but it appears I was mistaken?
Sort of - no gui.
But if you wanted a gui, one of the live CD's gets you a running 
environment which you could mount the disk on, and edit files with.

> I would have thought if I had the Fedora DVD, and could read it,
> I could just enter rescue mode with that?
Yes. edit the boot menu to start the kernel with linux rescue; just like 
the rescue CD.

> I'm amazed that one word in that file can stop Fedora booting.]
You shouldn't be. Even a character would do it eg in 
/boot/grub/grub.conf or /etc/fstab. No better in windows for eg.

DaveT.