1. To find the current visible (focused) activity via adb:
$ adb -s device_serial_number shell "dumpsys window windows" | grep "mFocusedApp"
2. Which activity life cycle method is called with persistent data when an app is force closed and restarted ?
3. How to make an android phone to call a number from commandline using adb ?
$ adb shell am start -a android.intent.action.CALL -d tel:9008174697