Linux grub

The default =0 line indicate that the first partition in this list

Time out =5 grub to pause for ten second before booting the default partition

Splashimage=(hd0,4) /grub/splash.xpm.gz. splash image line looks in the fifth partition on

the first disk(hd0,4) in this case /dev/hda5 grub loads splash.xpm.gz as the image on the splash screen ( /boot/grub/splash.xpm.gz) the splash screen appears as the background of the boot screen

Os name

This line means th following two files are stored in the (had,4) partition

[hd0,0]first hd0,1 partition

kernel image file location

initial RAM disk image

rootnoverify (hd0.0) line indicates that GRUB should not try to mount the partition

chainloader +1 

 This is different from the aforementioned root (hd0,0) directive, as rootnoverify

does not attempt to mount the noted partition in a Linux fashion.

Finally, the chainloader +1 directive points to the first sector of the noted

partition, where Microsoft Windows 7 continues the boot process:

chainloader +1

If you want to create an MD5 password for this file, run the grub-md5-crypt

command. You’ll be prompted for a password that is converted to an MD5 hash. You

can then copy this hash to the GRUB configuration file. If the password directive is

included before a stanza, it password-protects the entire menu. Users won’t be able

to edit the GRUB menu unless they know the password. If the password directive is

placed within a stanza, it prompts for the password before the option is selected.

             password –md5  (encrypted password)

·       Bios check the system and launch the first stage boot loader on the MBR of the primary   hard disk

·       First stage boot loader itself into memory and launch the second stage boot loader from boot partition

·       The second stage boot loader   load the kernel into memory, which in turn load any modules& mount root partition, read only

·       The kernel transfer control of the boot process to the /sbin/init program

·       /sbin/init program load all service and user interface tool and mount all partition listed in /etc/fstab

·       The user is presented with a login screen for freshly booted Linux system

                                                               

                                                                   System boot sequence

§  Grub stage one load MBR

§  Second stage  /boot/grub/stage1.5 (boot partition higher 1024 cylinder) 2

§  /boot/grub/grub.conf  ----- see selection os menu

§   /boot/vmlinux.2.6.18-5.elxen load to ram

§  initrd block device load (scsi)

§  /etc/rc.d/rc.sysinit

§  /etc/sysconfig/clock

§  /etc/rc.serial

§  /etc/inittab

§  init – run level 5

§  /etc/inittab run script called /etc/X11/prefdm (X display manger)

§  /etc/X11

§  gdm ,kdm or xdm

§  Depending on the content of the /etc/sysconfig/desktop file

§  /usr/X11R6/bin/xorg

§  /usr/X116/lib/modules

§  /etc/X11

§  /etc/X11/xorg.conf

Posted in: Basics,step by step