Add exit code mgmt to modules

modules/exit.go

@@ -0,0 +1,16 @@
+package modules
+
+var (
+	exitStatusCode int
+)
+
+// SetExitStatusCode sets the exit code that the program shell return to the host after shutdown.
+func SetExitStatusCode(n int) {
+	exitStatusCode = n
+}
+
+// GetExitStatusCode waits for the shutdown to complete and then returns the exit code
+func GetExitStatusCode() int {
+	<-shutdownCompleteSignal
+	return exitStatusCode
+}