A Gradle task for installing all application variants at once. Placed in the public domain.

build.gradle

def installAll = tasks.create('installAll')
installAll.description = 'Install all applications.'
android.applicationVariants.all { variant ->
  installAll.dependsOn(variant.install)
  // Ensure we end up in the same group as the other install tasks.
  installAll.group = variant.install.group
}