5.5:     GRUB bootloader

Introduction

GRUB is the default boot loader used by MEPIS Linux 7.0. A boot loader is software that tells your computer where to find operating systems to boot. When you start your computer, GRUB will provide you with a menu of choices. It is a very powerful boot loader that can load a wide variety of free operating systems, as well as proprietary operating systems with an indirect boot technique known as chainloading.

Overview

The typical default GRUB screen in MEPIS Linux 7.0 shows 3 kernel entries for MEPIS, any other detected OS, and a MEMTEST entry. It looks something like this (here for a dual_boot with Windows XP on a system with a single hard drive):

timeout 15
color cyan/blue white/blue
foreground ffffff
background 0639a1

gfxmenu /boot/grub/message

title MEPIS 6.9.51 at sda2, newest kernel
root (hd0,1)
kernel /boot/vmlinuz root=/dev/sda2 nomce quiet splash vga=791 
boot

title MEPIS at sda2, previous kernel (if any)
root (hd0,1)
kernel /boot/vmlinuz.old root=/dev/sda2 nomce quiet splash vga=791 
boot

title MEPIS at sda2, kernel 2.6.22-1-mepis-smp
root (hd0,1)
kernel /boot/vmlinuz-2.6.22-1-mepis-smp root=/dev/sda2
boot

title Microsoft Windows XP Professional at sda1
rootnoverify (hd0,0)
chainloader +1

title MEMTEST
kernel /boot/memtest86+.bin

Three kernel entries are listed for technical reasons: details in the Wiki discussion of GRUB under Links and Guides below.

The final entry, Memtest is a thorough, stand-alone memory test for 386, 486 and Pentium systems. It writes a series of test patterns to every memory address, then reads back the data written and compares it for errors. See Section 8.7.

Configuring GRUB

After successfully installing a dual-boot system, many people want to adapt it to their environment.

Configuring the boot menu timeout

It is possible to change the length of time for which the boot menu is shown. This is useful if you would like the computer to start up faster (without the delay of showing the menu) or would like more time to choose which operating system to start.

  1. Click KMenu --> System --> File System --> File Manager--Super User Mode, and supply the root password.
  2. In the navigation bar, type /boot/grub/menu.lst and hit return. This will open the configuration file for GRUB (menu.lst) that you can now edit.
  3. The first line contains text similar to the following:
    timeout 30
    
    This line determines the time, in seconds, during which the boot menu will be shown. Change the number on this line to the number of seconds you would like. Use 0 if you would not like the menu to be shown at all.
  4. Click File --> Save to save your changes and then Exit. Your changes should take effect the next time you restart your computer.

Changing the default operating system to boot

You can decide which operating system will be started automatically if you have not chosen one from the boot menu within a certain time.

Open the boot/grub/menu.lst file as root using the method indicated above, and add the following option just above the first “title” entry:

default n

Change the variable n to “0” to boot from the first entry in the menu, “1” for the second, and so forth. Save the file and exit. The changes will take effect the next time the computer boots.

An alternative method is to cut the entry for the OS you want to boot by default and paste it in first title position.


Troubleshooting

See the MEPIS Wiki links below for troubleshooting help.