Проблема с автозапуском программы на Raspberry Pi

sudo nano /etc/init.d/autostart.sh

Пишу скрипт:
#!/bin/bash
### BEGIN INIT INFO
# Provides:          autostart.sh
# Required-Start:
# Required-Stop:
# Default-Start:     2 3 4 5
# Default-Stop:      1 0 6
# Short-Description: simple description.
### END INIT INFO
export USER='pi'
sudo python /home/pi/prog21.py
exit 0

sudo chmod 755 /etc/init.d/autostart.sh

sudo update-rc.d autostart.sh defaults

Ответ:update-rc.d: using dependency based boot sequencing

insserv myscript

#import
import RPi.GPIO as GPIO
import os
import socket
import fcntl
import struct
import time
from time import gmtime, strftime, sleep

directory = '/media/TRANSCEND'
files = os.listdir(directory) 
images = filter(lambda x: x.endswith('.jpg'), files)  

# Define GPIO to LCD mapping
LCD_RS = 7
LCD_E  = 8
LCD_D4 = 25
LCD_D5 = 24
LCD_D6 = 23
LCD_D7 = 18


# Define some device constants
LCD_WIDTH = 16    # Maximum characters per line
LCD_CHR = True
LCD_CMD = False

LCD_LINE_1 = 0x80 # LCD RAM address for the 1st line
LCD_LINE_2 = 0xC0 # LCD RAM address for the 2nd line

# Timing constants
E_PULSE = 0.0005
E_DELAY = 0.0005

def main():
  # Main program block
  
  GPIO.setwarnings(False)
  GPIO.setmode(GPIO.BCM)       # Use BCM GPIO numbers
  GPIO.setup(LCD_E, GPIO.OUT)  # E
  GPIO.setup(LCD_RS, GPIO.OUT) # RS
  GPIO.setup(LCD_D4, GPIO.OUT) # DB4
  GPIO.setup(LCD_D5, GPIO.OUT) # DB5
  GPIO.setup(LCD_D6, GPIO.OUT) # DB6
  GPIO.setup(LCD_D7, GPIO.OUT) # DB7


  # Initialise display
  lcd_init()
  i=0
  GPIO.setmode(GPIO.BCM)
  GPIO.setup(21, GPIO.IN, pull_up_down=GPIO.PUD_UP)
  GPIO.setup(16, GPIO.IN, pull_up_down=GPIO.PUD_UP)
  while True:
    try:
        if GPIO.input(21) == False:
          i=i+1
          j=i+1
          g=8
          if j < g:
            lcd_string(images[i], LCD_LINE_1)
            lcd_string(images[j], LCD_LINE_2)
          else:
            i = g - 2
            j = g - 1
            lcd_string(images[i], LCD_LINE_1)
            lcd_string(images[j], LCD_LINE_2)
        if GPIO.input(16) == False:
			i=i-1
			j=i+1
			k=abs(i)
				if k == i:
					lcd_string(images[i], LCD_LINE_1)
					lcd_string(images[j], LCD_LINE_2)
				else:
					i=0
					j=1
					lcd_string(images[i], LCD_LINE_1)
					lcd_string(images[j], LCD_LINE_2)
        sleep(0.2)
    except KeyboardInterrupt:
        exit()
		  
def lcd_init():
  # Initialise display
  lcd_byte(0x33,LCD_CMD) # 110011 Initialise
  lcd_byte(0x32,LCD_CMD) # 110010 Initialise
  lcd_byte(0x06,LCD_CMD) # 000110 Cursor move direction
  lcd_byte(0x0C,LCD_CMD) # 001100 Display On,Cursor Off, Blink Off
  lcd_byte(0x28,LCD_CMD) # 101000 Data length, number of lines, font size
  lcd_byte(0x01,LCD_CMD) # 000001 Clear display
  time.sleep(E_DELAY)

def lcd_byte(bits, mode):
  # Send byte to data pins
  # bits = data
  # mode = True  for character
  #        False for command

  GPIO.output(LCD_RS, mode) # RS

  # High bits
  GPIO.output(LCD_D4, False)
  GPIO.output(LCD_D5, False)
  GPIO.output(LCD_D6, False)
  GPIO.output(LCD_D7, False)
  if bits&0x10==0x10:
    GPIO.output(LCD_D4, True)
  if bits&0x20==0x20:
    GPIO.output(LCD_D5, True)
  if bits&0x40==0x40:
    GPIO.output(LCD_D6, True)
  if bits&0x80==0x80:
    GPIO.output(LCD_D7, True)

  # Toggle 'Enable' pin
  lcd_toggle_enable()

  # Low bits
  GPIO.output(LCD_D4, False)
  GPIO.output(LCD_D5, False)
  GPIO.output(LCD_D6, False)
  GPIO.output(LCD_D7, False)
  if bits&0x01==0x01:
    GPIO.output(LCD_D4, True)
  if bits&0x02==0x02:
    GPIO.output(LCD_D5, True)
  if bits&0x04==0x04:
    GPIO.output(LCD_D6, True)
  if bits&0x08==0x08:
    GPIO.output(LCD_D7, True)

  # Toggle 'Enable' pin
  lcd_toggle_enable()

def lcd_toggle_enable():
  # Toggle enable
  time.sleep(E_DELAY)
  GPIO.output(LCD_E, True)
  time.sleep(E_PULSE)
  GPIO.output(LCD_E, False)
  time.sleep(E_DELAY)

def lcd_string(message,line):
  # Send string to display


  message = message.ljust(LCD_WIDTH," ")

  lcd_byte(line, LCD_CMD)

  for i in range(LCD_WIDTH):
    lcd_byte(ord(message[i]),LCD_CHR)

if __name__ == '__main__':

  try:
    main()
  except KeyboardInterrupt:
    pass
  finally:
    lcd_byte(0x01, LCD_CMD)
    lcd_string("Goodbye!",LCD_LINE_1)
    GPIO.cleanup()