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In this guide, you’ll learn how to install, reinstall, and configure the GRUB Legacy bootloader on your Linux system. We cover both methods—installing from a running system and from the GRUB shell on a rescue disk—plus how to edit your menu.lst and chainload Windows.

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Table of Contents

  1. Overview
  2. Installing from a Running System
  3. Reinstalling via the GRUB Shell
  4. Editing /boot/grub/menu.lst
  5. Chainloading Windows
  6. Command Reference
  7. Links and References

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Overview

GRUB Legacy (version 0.9x) remains a popular choice for legacy hardware or minimal setups. You’ll install its core files to /boot/grub and write stage1 into the Master Boot Record (MBR).
Always double-check your target device (e.g., /dev/sda) before running grub-install or setup. Installing to the wrong disk can overwrite critical data.

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Installing from a Running System

Use the grub-install utility to deploy GRUB Legacy without rebooting: 
sudo grub-install <device>
Example: install to the first disk (/dev/sda): 
sudo grub-install /dev/sda
By default, GRUB places its core files under /boot/grub. To change this directory, pass: 
sudo grub-install --boot-directory=/custom/boot /dev/sda
The --boot-directory option is helpful if you’re using a custom EFI or boot partition layout.

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Reinstalling via the GRUB Shell

When your system fails to boot, use a GRUB Legacy rescue disk:
  1. Boot from the rescue media and press c to open the grub> prompt.
  2. Identify and mount your boot partition (where /boot/grub resides): 
    grub> root (hd0,0)
  3. If unsure, locate stage1 with find: 
    grub> find /boot/grub/stage1
(hd0,0)
  4. Write GRUB’s stage1 into the MBR of the first disk: 
    grub> setup (hd0)
  5. Reboot—the GRUB menu should appear.

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Editing /boot/grub/menu.lst

The GRUB Legacy configuration file is a simple plain-text list of menu entries. Open it with your favorite editor: 
sudo vi /boot/grub/menu.lst
Lines starting with # and blank lines are ignored.

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Basic Linux Entry

title   My Linux Distribution
root    (hd0,0)
kernel  /vmlinuz root=/dev/sda1 ro quiet splash
DirectiveDescriptionExample
titleLabel shown in the GRUB menuMy Linux Distribution
rootGRUB device containing kernel & modules (disks/partitions start at 0)(hd0,0)
kernelPath to kernel (relative to root) plus boot parameters/vmlinuz root=/dev/sda1 ro quiet
initrdInitial RAM disk (if required)/initrd.img
moduleGRUB module to load (e.g., filesystem support, framebuffer)/boot/grub/i386-pc/915resolution.mod

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Omitting the root Directive

You can embed the device specifier within the kernel path: 
title   Alt Linux Entry
kernel  (hd0,0)/vmlinuz root=/dev/sda1 ro

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Chainloading Windows

To boot Windows or another OS via chainloading: 
title   Windows XP
root    (hd0,1)
makeactive
chainload +1
boot
  • root (hd0,1): Second partition of the first disk.
  • makeactive: Marks this partition as active (necessary for DOS/Windows).
  • chainload +1: Loads its first sector.
  • boot: Handoffs control to the loaded bootloader.

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Command Reference

CommandPurpose
grub-install <device>Install GRUB from a running Linux system
--boot-directory=<path>Specify custom location for GRUB files
root (hdX,Y)Set the GRUB root device in rescue shell
find /boot/grub/stage1Search for the stage1 file to identify correct partition
setup (hdX)Write stage1 into the MBR
title / kernel / initrd / moduleDefine menu entries in menu.lst
makeactive / chainloadChainload another bootloader (e.g., Windows)

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