Beginners • Re: Safely turn off Raspberry Pi 4 Model B whilst not attached to a monitor

Code:

#!/usr/bin/env python# BUTTON_ACTION.PY - Display Status of PI & Provide manual reboot/shutdown button# This is based on the project at https://gist.github.com/lbussy/9e81cbcc617952f1250e353bd42e7775# I chose to implement the 'scripted method' since the project was# going to run 24x7 and I only needed to provide some way for# someone else to reboot/shutdown the PI.# There are print statements since the service definition I used# included specs for capturing out/err to a log file.# This program needs to be run with the -u Python3 option so as not# to buffer output.# Here is the meaning of the led# BLINKING - Running, waiting for reboot/shutdown button to be pushed# ON has 2 meanings#    BUTTON HELD - Waiting x seconds to ensure reboot/shutdown requested#    BUTTON RELEASED - An error has occurred. This is likely short#                      lived since the service will restart and#                      the light will start blinking again.# OFF - PI is shutting down or starting up.__version__ = "V2.7"__program__ = "BUTTON_ACTION"__status__ = "Production"__success__ = 0__failure__ = 1from gpiozero import LED, Buttonfrom datetime import datetimefrom subprocess import callimport subprocessimport argparsefrom time import sleepimport datetime as dttmfrom sys import exc_infoimport sysfrom sys import exit as sys_exit # Named so to avoid confusion with Pt exit()from traceback import extract_tbimport traceback#************************************************************************************************# PDT_FUNCTION - Print standard date/time to precede line for WC programs# V1.0 - Initialdef pdt():    now = dttm.datetime.now()    return "["+now.strftime("%m-%d %H:%M:%S")+"] "#************************************************************************************************# https://docs.python.org/3/library/argparse.htmldef doArgs():    # parser will print errors. Only need to trap to return failure    try:        parser = argparse.ArgumentParser()        parser.add_argument("--shutdown", action="store_true",\                            help="Shutdown instead of rebooting", default=False)        args = parser.parse_args()            except:        return False   # --debug Provide information using for debugging    global shutdown     shutdown = args.shutdown        return True# End of doArgs()# Mainlinedef main():    print(pdt(),__program__,__version__)        # Parse Arguements    if not doArgs():        return False        if shutdown: print(pdt()+"Will shutdown instead of rebooting")        led = LED(19) # GPIO 19    led.blink() # Indicates running and waiting for button push    button = Button(6) # GPIO6 # Loop checking every few seconds to see if the button has been# pressed and held. When the button is first pressed, the led# changes from blinking to on. This is visual feedback to the# operator. If the button is held down, the led is turned off to# indicate the PI is rebooting/shutting down.# If the led is left on, a problem has occurred.    loop_sleep_time = 2 # Time to wait between checking for button pressed    next_check_net_cnt = net_check_after + 1 # For check on first pass    print_net_info_once = True    try:        # ***** MAIN LOOP ****        while True: # Ends only with a reboot/shutdown or exception exit                            if button.is_pressed:                print(pdt()+__program__+": Button pressed")                led.on() # Led user know the button pressed detected                sleep(5) # User has to hold the button down                if button.is_pressed:                    led.off() # Let user know reboot/shutdown in progress                    sleep(1)                    if shutdown:                        print(pdt()+"Shutting down")                        call(["sudo","shutdown","-h","now"])                    else:                        print(pdt(),"Rebooting")                        call(["sudo","reboot"])                    return __failure__ # Should never get here                else:                    led.blink() # Let user know reboot/shutdown was not initiated                                sleep(loop_sleep_time) # Don't make too short or higher CPU is used.            # There should not be exceptions# If there is, make sure we log it nicely    except:        led.on() # Keep light on to say there is a problem.        exc_type, exc_value, exc_traceback = exc_info()        type=exc_type.__name__        summ = str(extract_tb(exc_traceback))        print (pdt()+__program__+": Exception '"+type+"="+str(exc_value)+"'. Traceback: "+summ)        return __failure__ # Return error#    return __success__ # We should never get here.      # MAIN  if __name__ == "__main__":    rtn=main()    sys_exit(rtn)