Can I get the original MAC address after it has been changed?

I am using some linux machines that have had their MAC address changed. I would like to be able to read it back with a shell script.

Is the original MAC address stored anywhere except the sticker on the box? How do I bring back the original hardware address?

you can check you dmesg logs it will report the hardware MAC address as seen on boot.

on one of my boxes the output looks like:

gbeech@ny-man01:~$ dmesg | grep eth0
[    6.533181] eth0: Broadcom NetXtreme II BCM5709 1000Base-T (C0) PCI Express found at mem d6000000, IRQ 36, node addr 00:21:9b:a0:b7:cc

what you are interested in is the node addr 00:21:9b:a0:b7:cc bit at the end

Might be on the physical card, or etched onto the motherboard. I doubt you can access it from a script however.