title: Where is the ANDROID_SDK_ROOT in ubuntu server?
body: <p>I run a build on a ubuntu 16.04 server with no xorg or GUI of any kind, and I am trying to run a simulator on it. this is what I get on the console</p>
  
  <pre><code>$ /opt/android//tools/emulator -engine classic -ports 5688,5689 -report-console tcp:5815,max=60 -avd Nexus_5X_API_25 -no-snapshot-load -no-snapshot-save -no-window
  PANIC: Cannot find AVD system path. Please define ANDROID_SDK_ROOT
  Build was aborted
  </code></pre>
  
  <p>How do I set the <code>ANDROID_SDK_ROOT</code> in ubuntu?</p>