title: Modify PATH for gitlab-runner
body: <p>I want to install a <code>gitlab-runner</code> (executor <code>shaell</code>) on my Windows 10 box. I start the job on the gitlab server and it always ends up with the message <code>the command "git" cannot be found</code> (roughly translated into english).
  As a matter of fact <code>git</code> is not part of my path.
  How can I modify my <code>PATH</code> variable for the shell the <code>gitlab-runner</code> starts?</p>
  
  <p>To use git on the command line in windows I usually set it with the statement: <code>PATH %PATH%C:\Program Files\Git\bin</code>.</p>
  
  <p>Is it documented somewhere, <code>git</code> has to be available to the runner?
  How can I see the command line the runner invokes (i.e. the call to git)?</p>