title: "Error: 'ANDROID_HOME' environment variable is set to non-existent path" on ubuntu
body: <p>I want to build an ionic app but when I run <code>ionic build android</code> on terminal it gives below error,</p>
  
  <pre><code>Running command: /home/shamil/learn/Ionic/myApp/hooks/after_prepare/010_add_platform_class.js /home/shamil/learn/Ionic/myApp
  add to body class: platform-android
  Running command: /home/shamil/learn/Ionic/myApp/platforms/android/cordova/build 
  [Error: 'ANDROID_HOME' environment variable is set to non-existent path: /Android/Sdk
  Try update it manually to point to valid SDK directory.]
  ERROR building one of the platforms: Error: /home/shamil/learn/Ionic/myApp/platforms/android/cordova/build: Command failed with exit code 2
  You may not have the required environment or OS to build this project
  Error: /home/shamil/learn/Ionic/myApp/platforms/android/cordova/build: Command failed with exit code 2
      at ChildProcess.whenDone (/usr/local/lib/node_modules/cordova/node_modules/cordova-lib/src/cordova/superspawn.js:139:23)
      at ChildProcess.emit (events.js:110:17)
      at maybeClose (child_process.js:1015:16)
      at Process.ChildProcess._handle.onexit (child_process.js:1087:5)
  </code></pre>
  
  <p>I have given the correct path where sdk exist, but why there such an error exist? I have searched enough to solve this matter, but it still gives the same error. </p>
  
  <p>Please help.</p>