title: Hex Dump Specific Parts of File - Bash
body: <p>I'm trying to write a bash script to audit hard drives that have been wiped to ensure the wiping system is working properly.  I would like to find a way to hex dump specific parts of a drive without having to hex dump the entire drive and extract the parts I'd like (as this seems to run for too long to make the script worth writing). Ideally, I'd be able to grab parts from the beginning, middle, and end of the drive. </p>
  
  <p>I would like to take the output of the hex dump and check it for the existence of only one character (indicating the drive has been successfully wiped).  This part, I can handle, but I thought it may affect any advice I may get.</p>
  
  <p>I've used head piped into xxd to get the beginning of the file which has worked, but I'm still stuck on the other parts.  I've tried using tail to just get the end of the drive, but that doesn't seem to work quickly either.  Is it possible to do this efficiently?  Possibly using dd or something else and pipe it into a hex editor?  I've looked through options for xxd as well as hexdump to no avail.  If someone could point me in the right direction, it would be greatly appreciated!</p>