How to view the contents of an initrd image

Linux uses the initrd or initial ram-disk during the boot process. Linux kernel is very modular as you know. While the kernel main file contains only the most needed stuff, rest of the kernel, drivers included, reside in separate files – the kernel modules.

It would be impossible to create a single kernel binary image that would suit all the hardware configurations out there. Instead, kernel supports the initrd. initrd is a virtual file-system that contains drivers (kernel modules) needed to boot the system. For instance, very often a SCSI controllers drivers reside inside of the initrd. Kernel needs a SCSI controller driver to boot the operating system, but it does not include it, nor it can read it from hard-disk (you’d need a driver for the hard-disk, right?). And this is when the initrd becomes very handy.

To extract the content of initrd file, use the following command:

gunzip < initrd-2.6.31.5-0.1-desktop | cpio -i --make-directories