I have a notebook which is now dual boot: It has Windows XP as well as Redhat loaded, and the bootloader is grub. I might add that there are two stange other partitions,
one the ominous Windows "hidden partition" and the other a small "Dell Utility partition"
The boot loader is grub.

Here is what I want to do: I would like to shrink the existing Redhat partition by
50% (7Gb) and then install Debian 3.0 (Woody). (I'll settle for Knoppix-Debian
if necessary) Here are the issues:

(0) If I shrink the Redhat partition, will the grub get confused? How about the swap space?
Do I have to tell Redhat where it is after shrinking?

(1) How do I make it that at the end of everything I have all three Operating Systems availabel through grub?

BTW, I am keeping Windows around not because I want o keep it in the long run. Once I have found the distribution that I like the most, Windows will be happily deleted. (I already
removed the little Windows plaque ("designed for XP') and pasted it only a certain utility in my bathroom.) But I want to learn how to set up triple boot (with Windows still around) just to learn.

I cannot answer all of your questions, but I know some of it.

GRUB knows about partitions and filesystems, so you don't have to worry about resizing partitions, GRUB will still find its way. This is in distinction to LILO, which you would have to recompile to get it to work (although simply reducing the size of a partition shouldn't be a problem either, I would think.)

As for 3 partitions, or 4, you just need to change the GRUB menu with the new OS installed on the new partition.

The Linux Documentation Project (www.tldp.org) has good documentation on GRUB that you should look at when configuring GRUB.

As for the Redhat swap partition, before you do anything, you should really do an inventory of what partitions you already have and are using. Check out the /etc/fstab file in your RedHat distro for a start. Oh, and as the old saw goes, if you have anything you really need or want to keep on your PC, you should do a backup before messing around with partitions and installing another OS. There is always the possibility that you or the software will screw something up.

Good luck!

I've used three different distros which are rpm-based, with grub as the bootloader: OpenLinux, RedHat, and Suse. I can tell you this, with limited qualification: you can have as many distros as you want, up to the limit of bootable partitions (whatever that is), if you follow a few simple rules:
Rule 1) choose which distro will be the master, with grub installed and working (installed to the MBR is included in this rule).
Rule 2) install anything from microsoft first, then install Linux (microsoft will commandier the MBR and render it unusable by Linux. Install Linux after microsoft, then configure grub and have both systems bootable).
Rule 3) All subsequent Linux distros you choose to add, install grub to the root partition of the subsequent distro, NOT TO THE MBR (you've already done that with the one you chose to be Master).
Rule 4) after installing each distro (one at a time, please), copy the relevant entries from /boot/grub/menu.lst (or /boot/grub/grub.conf) to the same file in the master grub config file.

If you follow these simple rules, you will have a multi-distro system, with a working grub menu, from which you can select a distro to boot.

Please notice that I've left out the parts about mounting partitions to get at files not otherwise available when running a particular distro. That is your homework. That is how you will learn to be your own sysadmin. (That's pretty much a requirement in this Linux world: Learn How To Be Your Own Sysadmin).

The four rules above pretty much lay it out for you. The only limit is the number of bootable partitions you are alloowed. As far as I know, you can easily have one primary bootable partition, one extended partition, with several bootable partitions within that extended partition.

Do what I did. Experiment, learn, grow.

Best of luck; best wishes. Hope to hear about your accomplishments.

Thanks for the nice HOWTO.

Quck follow-up:
How does one install grub to a root partition? Where shoudl I look?

Most distros have an installer - that will do it for you. Some don't give you a choice, but Debian should be better than that.

If the install is command based, there will be instructions - not a concern in your case.

As an aside, the only reason to install grub at all after the first ("master" as bigrigdriver called it), is to get the format of the grub.conf/menu.lst entry. Other than that it is not required - you can just point straight to the kernel image.
Does no damage if installed to a partition, so I'd also advise you do install it for each distro.

Hm... what does that mean "point straight to the kernel" (what points the MBR, GRUB,...)?

Isn't chainloading bootloaders enough to be going on with?

I can vouch for that. The "new" debian-installer, introduced with 3.1/Sarge, explicitly gives you the option of installing Grub to the MBR (or not), as you desire.

I have heard of someone with 32 different Operating Systems installed on one computer and that is the max that can be done.

theory_prof, hold on one second. Do you have just one hard drive? If so, you might need to make an extended partition so you can have more primary partitions, which you will need. You'll need / partitions for 2 more OSs, right? I believe you can share the swap space, but still....