echo "MAIN_LOOP: sleeping $INTERVAL seconds." >&2
  sleep "$INTERVAL" & SLEEP_PID=$!
  while kill -0 $SLEEP_PID; do
    echo "MAIN_LOOP: sleeping..." >&2
    while read -r -t 1 CLIENT_ID CLIENT_COMMAND CLIENT_PARAMETERS; do
      echo "COMMAND_CHANNEL: got $CLIENT_ID $CLIENT_COMMAND $CLIENT_PARAMETERS" >&2
    done <"$FIFONAME"
  done
  echo "MAIN_LOOP: continuing with next iteration" >&2