How To Create initrd Image Temporary File System initrd

1)initrd is a image file.
2)initialize Ram Disk Image.
3)initrd is temporary file system used in the boot Process of the Linux Kernel.
4)initrd contain basic executable files utilities and Essential Drivers, that leads kernel to mount root File system.
5)In these temporary file system it contain directory, bin,etc,init,dev,lib,loopfs,proc,sys,sysroot File is init.
6)This initrd image Contain the Same version & Number of kernel
Example
initrd Image initrd-2.6.9-5.EL.img
kernel vmlinuz-2.6.9-5.EL


How To Extract Initrd File.
#gunzip < /boot/initrd.img | cpio -i
cpio -i It will Extract the Image.
-o Create the Image
-v Verbose.
1) Copying files from Archive
2) Extracting Files from Archive
#ls /etc/*.conf | cpio -o --forma=tar > conf.tar