Working with Boot Loader
Wednesday, May 13, 2009
Let us know, how we can configure our boot loader.In linux the file is
/boot/grub/grub.conf. You will find a soft link of this file in /etc directory.
The boot loader file specifies the computer where the system files exist in our system so that the computer can boot perfectly. The grub.conf understands Microsoft’s boot loader file also. If we have multiboot system, we can configure the linux boot loader file, /boot/grub/grub.conf to set the default operating system and how long the computer can wait before booting the system with the default operating system.
Let us have a look at the screen shot below for /boot/grub/grub.conf file.
According to the above example, there is only one operating system loaded – the Red Hat Enterprise Linux, see the title section here. You are open to change the contents of the title . The default=0 tells the system to boot using the OS referred by the first title. The timeout=5 defines that the system will wait for 5 seconds before booting with the default Operating system. The splashimage is nothing but the image you see in the boot loader screen. Here, considering you have a dual booting system, you may choose which Operating System will be loaded. The hiddenmenu does what its name implies – it hides the menu. The root (hd0,0) indicates where the system will find the root of the booting related files. In Red Hat linux, the name of the directory is /boot. The hd0,0 section could be different in accordance with the partition information in your hard disk. Here hd0,0 indicates the first partition in the first hard disk. The next two lines defines the kernel and initrd image file name.Let us check another grub.conf file below –
# grub.conf generated by anaconda
#
#boot=/dev/hda
default=0
timeout=10
splashimage=(hd0,1)/grub/splash.xpm.gz
title Red Hat Linux (2.4.18-14)
root (hd0,1)
kernel /vmlinuz-2.4.18-14 ro root=LABEL=/
initrd /initrd-2.4.18-14.img
title DOS
rootnoverify (hd0,0)
chainloader +1
# end of file
According to the above file the computer’s default operating system is Red Hat Linux. You
know, why !!. If you want to set DOS as the default, what we can do is just change the
value for ‘default’. Replace 0 with 1.
At this point if you reboot the computer you will see at the top Red Hat Linux exists though the DOS has been selected. If you interchange the title directives, you will see at the top DOS exists and it has also been selected.
Here is the modified /boot/grub/grub.conf file....
# grub.conf generated by anaconda
#
#boot=/dev/hda
default=0
timeout=20
splashimage=(hd0,1)/grub/splash.xpm.gz
title DOS
rootnoverify (hd0,0)
chainloader +1
title Red Hat Linux (2.4.18-14)
root (hd0,1)
kernel /vmlinuz-2.4.18-14 ro root=LABEL=/
initrd /initrd-2.4.18-14.img
# end of file
Please note that, there is no need to run any command to make the change effective.
/boot/grub/grub.conf. You will find a soft link of this file in /etc directory.
The boot loader file specifies the computer where the system files exist in our system so that the computer can boot perfectly. The grub.conf understands Microsoft’s boot loader file also. If we have multiboot system, we can configure the linux boot loader file, /boot/grub/grub.conf to set the default operating system and how long the computer can wait before booting the system with the default operating system.
Let us have a look at the screen shot below for /boot/grub/grub.conf file.
According to the above example, there is only one operating system loaded – the Red Hat Enterprise Linux, see the title section here. You are open to change the contents of the title . The default=0 tells the system to boot using the OS referred by the first title. The timeout=5 defines that the system will wait for 5 seconds before booting with the default Operating system. The splashimage is nothing but the image you see in the boot loader screen. Here, considering you have a dual booting system, you may choose which Operating System will be loaded. The hiddenmenu does what its name implies – it hides the menu. The root (hd0,0) indicates where the system will find the root of the booting related files. In Red Hat linux, the name of the directory is /boot. The hd0,0 section could be different in accordance with the partition information in your hard disk. Here hd0,0 indicates the first partition in the first hard disk. The next two lines defines the kernel and initrd image file name.Let us check another grub.conf file below –# grub.conf generated by anaconda
#
#boot=/dev/hda
default=0
timeout=10
splashimage=(hd0,1)/grub/splash.xpm.gz
title Red Hat Linux (2.4.18-14)
root (hd0,1)
kernel /vmlinuz-2.4.18-14 ro root=LABEL=/
initrd /initrd-2.4.18-14.img
title DOS
rootnoverify (hd0,0)
chainloader +1
# end of file
According to the above file the computer’s default operating system is Red Hat Linux. You
know, why !!. If you want to set DOS as the default, what we can do is just change the
value for ‘default’. Replace 0 with 1.
At this point if you reboot the computer you will see at the top Red Hat Linux exists though the DOS has been selected. If you interchange the title directives, you will see at the top DOS exists and it has also been selected.
Here is the modified /boot/grub/grub.conf file....
# grub.conf generated by anaconda
#
#boot=/dev/hda
default=0
timeout=20
splashimage=(hd0,1)/grub/splash.xpm.gz
title DOS
rootnoverify (hd0,0)
chainloader +1
title Red Hat Linux (2.4.18-14)
root (hd0,1)
kernel /vmlinuz-2.4.18-14 ro root=LABEL=/
initrd /initrd-2.4.18-14.img
# end of file
Please note that, there is no need to run any command to make the change effective.
Labels: anaconda, boot, boot loader, chainloader, command, configuration, grub, grub.cong, Linux, linux boot loader, multiboot, unix
posted by Gautam at 11:30 PM, | 
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