Reinstalling grub from single user mode

1. Boot the system from an installation boot medium.

2. Type linux rescue at the installation boot prompt to enter the rescue environment.

3. Type chroot /mnt/sysimage to mount the root partition.

4. Type /sbin/grub-install /dev/hda to reinstall the GRUB boot loader, where /dev/hda is the boot partition
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5. Review the /boot/grub/grub.conf file, as additional entries may be needed for GRUB to control additional operating systems.

6. Reboot the system.