sending unix date to lcd

Any suggestions?

Now i have this but it sends it out as hex and after it has been displayed lcd shows some number starting with a minus (-)

#include <LiquidCrystal.h>
LiquidCrystal lcd(12, 11, 5, 4, 3, 2);


long txt = 0;


void setup() {         
  lcd.begin(16, 2);         
  Serial.begin(9600);      

lcd.setCursor(0, 0);
  lcd.print("time");
delay(1000);
lcd.clear();
                          
}

void loop() {
  txt = Serial.read();

lcd.setCursor(0, 0);
lcd.print(txt);

delay(100);

}

The time should state until it changes or is send again via serial.

  txt = Serial.read();

Why are you storing a byte in a long variable? Why are you not checking that there is data to read before reading it?

delay(100);

If you are not going to do anything, why not not do it right away? This delay call is absolutely useless.

Why are you storing a byte in a long variable?

I want it to be text? I have no clue how to do this

If you are not going to do anything, why not not do it right away? This delay call is absolutely useless.

If there is no delay the lcd will flicker

The time should state until it changes or is send again via serial.

The LCD won't flicker if you don't write to it, unless you get serial data.

I want it to be text? I have no clue how to do this

Is that a question or a statement? Perhaps you should start with defining what is sending data to the Arduino, via the serial port, and HOW.