Can't run python script on startup. Raspberry Pi 4

Question

I am trying to run a python script when my Raspberry pi 4 boots. THis python script works when I run it directly, with no errors. I have edited the crontab file to do this as can be seen below:

# Notice that tasks will be started based on the cron's system # daemon's notion of time and timezones. # # Output of the crontab jobs (including errors) is sent through # email to the user the crontab file belongs to (unless redirected). # # For example, you can run a backup of all your user accounts # at 5 a.m every week with: # 0 5 * * 1 tar -zcf /var/backups/home.tgz /home/ # # For more information see the manual pages of crontab(5) and cron(8) # # m h dom mon dow command @reboot python /home/pi/FUZEGUI.py > /home/pi/FUZEGUIlog.txt 

The log file has no information in it. I have tried a different method, rc.local;

# By default this script does nothing. # Print the IP address _IP=$(hostname -I) || true if [ "$_IP" ]; then printf "My IP address is %s\n" "$_IP" fi printf "Launching FUZE GUI" sudo python home/pi/FUZEGUI.py & exit 0 

But that doesn't work either. Script

#!/usr/bin/env python try: import Tkinter as tk except: import tkinter as tk from PIL import Image, ImageTk import time import threading root = tk.Tk() root.attributes('-fullscreen', True) root.geometry("800x800") # Define Canvas canvas = tk.Canvas(root, width=800, height=800) canvas.grid(row=0, column=0) # translates an rgb tuple of int to a tkinter friendly color code def _from_rgb(rgb): return "#%02x%02x%02x" % rgb # Called when user presses View Log button def viewLogRaise(): # Hide Previous Windows canvas.itemconfigure(logButtonWindow, state="hidden") canvas.itemconfigure(titleLabelWindow, state="hidden") # Open Closed Windows canvas.itemconfigure(backButtonWindow, state="normal") canvas.itemconfigure(logTextWindow, state="normal") canvas.itemconfigure(scrollbarWindow, state="normal") #I want to read the file continuously at this point. t =threading.Thread(target=readFile) t.start() def backToMenu(): # Hide Previous Windows canvas.itemconfigure(backButtonWindow, state="hidden") canvas.itemconfigure(logTextWindow, state="hidden") canvas.itemconfigure(scrollbarWindow, state="hidden") # Open Closed Windows canvas.itemconfigure(logButtonWindow, state="normal") canvas.itemconfigure(titleLabelWindow, state="normal") def follow(thefile,reading): count= 0 thefile.seek(0, 2) count += 1 while reading == True: line = thefile.readline() if not line: time.sleep(0.1) continue yield line def readFile(): logfile = open("fast.log", "r") loglines = follow(logfile,True) for line in loglines: logText.insert(tk.END, line) # Background pathToGif = "redpoly4.jpg" # red_background=Image.open("redBackground.gif") backgroundImage = ImageTk.PhotoImage(file=pathToGif) canvas.background = backgroundImage bg = canvas.create_image(0, 0, anchor=tk.NW, image=backgroundImage) titleLabel = tk.Label(root, fg="white", text="FUZE", borderwidth=2, relief="solid", bg=_from_rgb((239, 36, 37)), font=("Courier", 100)) titleLabelWindow = canvas.create_window(400, 120, window=titleLabel) logButton = tk.Button(root, fg="white", text="View Log", command=viewLogRaise, borderwidth=2, relief="raised", bg=_from_rgb((239, 36, 37)), font=("Courier", 46)) logButtonWindow = canvas.create_window(400, 320, window=logButton) backButton = tk.Button(root, fg="white", text="Back", command=backToMenu, borderwidth=2, relief="raised", bg=_from_rgb((239, 36, 37)), font=("Courier", 20)) backButtonWindow = canvas.create_window(70, 360, window=backButton) canvas.itemconfigure(backButtonWindow, state="hidden") logText = tk.Text(root, bg="white", height=22, width=60, borderwidth=2, relief="solid") logTextWindow = canvas.create_window(450, 208, window=logText) # attach text widget to scrollbar scrollbar = tk.Scrollbar(root) scrollbar.grid(row=1,column=3) scrollbarWindow = canvas.create_window(710,200, window=scrollbar) logText.config(yscrollcommand=scrollbar.set) scrollbar.config(command=logText.yview) canvas.itemconfigure(scrollbarWindow,state="hidden") canvas.itemconfigure(logTextWindow, state="hidden") root.mainloop() 

Answer 1

You've run into a well-known limitation with cron. The question has been asked and answered here many times. This recent example highlights the two (at least two) choices you have:

1. use cron (older, simpler)
2. use systemd (newer, more complex)

The answer to your question in the context of cron usage is this:

If your script runs from the command line, but fails to run from @reboot in your crontab, then put a sleep command before your other command; e.g.:

@reboot (sleep 15; <your command here>) 

You can also help yourself by redirecting your stderr stream to a file - otherwise any error messages encountered will go to the "bit bucket":

@reboot (sleep 15; <your command here>) >> /home/pi/cronjoblog.txt 2>&1 

>> /home/pi/cronjoblog.txt is a "redirection"; what goes to the screen, is re-directed to the specified file.

stderr is the "error stream" & is numbered "2" by convention

stdout is the "normal output", numbered "1" by convention

2>&1 is an obtuse way of telling your system that you want your error messages to be "merged" with your normal output.

Answer 2

If my understanding is correct, since you want this to occur prior to logging in (on boot) you will not have input your password to determine user/root, so i would remove the sudo in the argument.

In rc.local, instead of sudo python ... & try inputting the full path to python. I had a similar issue, and this worked for me: sudo /usr/bin/python [PATH TO SCRIPT.py] &