title: How can I know if `git gc --auto` has done something?
body: <p>I'm running <code>git gc --auto</code> as part of an automatic saves script. I'd like to run further cleanup if <code>git gc --auto</code> has done something, but I'd like to spare the hassle if <code>git gc --auto</code> doesn't feel like something need to be done. Is there a way to check the return value of <code>git gc --auto</code>, or to check beforehand if it is necessary to run it ?</p>