Explain About Grub.conf file in Redhat Linux Server

Grub.conf file it has 7 lines. there default file format.

timeout=5

splashimage=(hd0,0)/grub/splash.xpm.

title Red Hat Enterprise Linux Server (2.6.18-53.el5)

root (hd0,0)

kernel /vmlinuz-2.6.18-53.el5 roroot=/dev/VolGroup00/LogVol00

initrd /initrd-2.6.18-53.el5.img

FIRST LINE: timeout=5
while the system boot it will wait up to 5 second user to select the kernel.

SECOND LINE: splashimage=(hd0,0)/grub/splash.xpm.
it will load the (hd0,0)/grub/splash.xpm.  image as the background when we were booting the OS
How to create teh splash.xpm.gz Image
#convert imagelocation.png -resize 640x480 -colors 14 splash.xpm
#gzip splash.xpm

THIRD LINE:title Red Hat Enterprise Linux Server (2.6.18-53.el5)
It will give the kernel label as the “title Red Hat Enterprise Linux Server (2.6.18-53.el5)”

FOURTH LINE:root (hd0,0)
Here (hdx,y) x -> Hard Drive y-> Partition
we need to give the Correct partition
otherwise it will through following error message
Error 22: No such partition

FIFTH LINE:kernel /vmlinuz-2.6.18-53.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
it will load the kernel image and mount root file system as mention in root=
/dev/VolGroup00/LogVol00 refer to the logical volume root file system located in these logical volume.
And kernal execute /sbin/init process it is parent process PID is 1.

SIX LINE:initrd /initrd-2.6.18-53.el5.img
initrd it has executable driver module.
initrd Intilize the Ram Disk
if we face the any problem to load initrd we need to reinstall by using mkinitrd.