title: How to pass Windows host env into Vagrantfile?
body: <p>I have a Windows-7 host running Vagrant (1.9.1), from which I start a CentOS guest VM</p>
  
  <p>I want to pass a Windows environment variable into the guest via the Vagrantfile.</p>
  
  <p>Let's call the environment variable ABC</p>
  
  <p><code>&gt;echo %ABC%
  123</code></p>
  
  <p>I know I can pass static values in as:</p>
  
  <p><code>config.vm.provision :shell, path: "scripts/bootstrap.sh", env: {"MYVAR" =&gt; "123"}</code></p>
  
  <p>But I don't know how to translate the env var - this doesn't work (passes literal: %ABC%):</p>
  
  <p><code>config.vm.provision :shell, path: "scripts/bootstrap.sh", env: {"MYVAR" =&gt; "%ABC%"}</code></p>
  
  <p>Any help appreciated</p>