Linux - Arduino key : Arduino part

int buttonPin = 2;
int ledPin =  13;
int buttonState = 0;
int lastState = 0;

void setup() {
    Serial.begin(9600);
    pinMode(ledPin, OUTPUT);
    pinMode(buttonPin, INPUT);
}

void loop(){
    buttonState = digitalRead(buttonPin);
    if (buttonState == HIGH) {
        digitalWrite(ledPin, HIGH);
        if(lastState == LOW)
        {
            Serial.print(1);
        }
    }else {
        digitalWrite(ledPin, LOW);
    }
    lastState = buttonState;
}