When I cancel gradle it showing following line.
Information:Gradle tasks [:app:generateDebugSources, :app:generateDebugAndroidTestSources, :app:mockableAndroidJar, :app:compileDebugAndroidTestSources, :app:compileDebugUnitTestSources, :app:compileDebugSources]
Error:java.io.IOException: error=13, Permission denied
just go to /home/suUs12/Android/Sdk/build-tools/21.1.2/
and then right click on aapt
file , properties -> permissions
and check Allow executing file as program
. then close the window.
Hope so this Helps