Caution: Installing GRUB's stage1 in this manner will erase the
normal boot-sector used by an OS.
GRUB can currently boot GNU Mach, Linux, FreeBSD, NetBSD, and OpenBSD
directly, so using it on a boot sector (the first sector of a
partition) should be okay. But generally, it would be a good idea to
back up the first sector of the partition on which you are installing
GRUB's stage1. This isn't as important if you are installing GRUB on
the first sector of a hard disk, since it's easy to reinitialize it
(e.g. by running `FDISK /MBR' from DOS).
If you decide to install GRUB in the native environment, which is
definitely desirable, you'll need to create a GRUB boot disk, and
reboot your computer with it. Otherwise, see Installing GRUB using grub-install.
Once started, GRUB will show the command-line interface
(see Command-line interface). First, set the GRUB's root
device1 to the
partition containing the boot directory, like this:
grub> root (hd0,0)
If you are not sure which partition actually holds this directory, use the
command find (see find), like this:
grub> find /boot/grub/stage1
This will search for the file name /boot/grub/stage1 and show the
devices which contain the file.
Once you've set the root device correctly, run the command
setup (see setup):
grub> setup (hd0)
This command will install the GRUB boot loader on the Master Boot
Record (MBR) of the first drive. If you want to put GRUB into the boot
sector of a partition instead of putting it in the MBR, specify the
partition into which you want to install GRUB:
grub> setup (hd0,0)
If you install GRUB into a partition or a drive other than the first
one, you must chain-load GRUB from another boot loader. Refer to the
manual for the boot loader to know how to chain-load GRUB.
After using the setup command, you will boot into GRUB without the
GRUB floppy. See the chapter Booting to find out how to boot
your operating systems from GRUB.
 Note that GRUB's root device doesn't necessarily mean
your OS's root partition; if you need to specify a root partition for
your OS, add the argument into the command kernel.
Published under the terms of the GNU General Public License