A Simple Python script to blink a Raspberry Pi LED.

import RPi.GPIO as GPIO
from time import sleep

GPIO.setwarnings(False)
GPIO.setmode(GPIO.BOARD)  # Uses the physical pin numbering
GPIO.setup(7, initial=GPIO.LOW)  # Set GPIO pin to off

while True:
    GPIO.output(7, GPIO.HIGH)
    sleep(0.2)
    GPIO.output(7, GPIO.LOW)
    sleep(0.2)

Change pin numbers as needed.

We can also do this with BASH.