Groovy script for capturing response header form 1st test st

HI,

I have following scenario:

Need to validate a file update for which I need to capture finger print of existing file through Fetch API's Response header "Fingerprint" and add it with XML as request header "Fingerprint" through PUT API

How can I do that with Groovy script e.g.

Step1: Fetch file -- "Fingerprint" Response header
Step2: Groovy script --> Capture "Fingerprint" Response header from Step1
Step3: Store file with "Fingerprint" from Step1 as Request Header

Its really urget...please Help