title: How can I get my C code to automatically print out its Git version hash?
body: <p>Is there an easy way to write C code that can access its Git version hash? </p>
  
  <p>I wrote software in C to collect scientific data in a laboratory setting. My code records the data it collects in a .yaml file for later analysis. My experiments change from day-to-day and I often have to modify the code. To keep track of  revisions, I use a git repository. </p>
  
  <p>I would like to be able to include the Git revision hash as a comment in my .yaml data files. That way, I could look at the .yaml file and know exactly what code was used to generate the data shown in that file. Is there an easy way to do this automatically? </p>