my first post, so apologize if i do something wrong.
I wrote a python script using tkinter in python3, which works fine with IDLE3. I wanted this script to run when I started Pi, so I followed the following procedure to run @reboot using the cron job. http://www.instructables.com/id/Raspberry-Pi-Launch-Python-script-on-startup/step4/Add-to-your-crontab/
I initially received an initialization error, so I added 120 /; to '/ bin / sleep;' to the @reboot line, so now it reads as follows and seems to wait long enough for everything to initialize after loading. @ reboot / bin / sleep 120; sh / home / pi / launcher.sh> / home / pi / logs / cronlog 2> & 1
But after that, my cronlog shows the following error:
Traceback (last last call): File "walk.py", line 29, in MyGUI = Tk () File "/usr/lib/python3.2/tkinter/ init .py", line 1701, in init self.tk = _tkinter.create (screenName, baseName, className, interactive, wantobjects, useTk, sync, use) _tkinter.TclError: there is no display name and there is no environment variable $ DISPLAY
Now I saw this error for other threads, and many seem to relate to initializing libraries that I don't use. I want to add that my code works different from downtime, different from the terminal, I made launcher.sh and made it executable, and if I ran "sh launcher.sh" from the terminal, it works fine, so the launcher.sh script looks like not bad. but when I download, I get the above error, and I have no idea why? Please, help.
I do not have a copy of the code on this computer, but I will try to copy it and send it as a comment if anyone thinks this will help.
Thanks in advance Paul
FULL CODE BELOW
import sys import tkinter #might not be needed from tkinter import * import pymysql import os.path import datetime import json #Define local database connection try: localdb = pymysql.connect(host="localhost", user="root", passwd="p054169q", db="walk") except Exception as e: sys.exit('Can not locate localdb') lcur = localdb.cursor() #Define web database connection (Maybe add later for easy sync) #Initialise GUI using Tkinter MyGUI = Tk() #Remove title bar from GUI window #(BUG: Causes window not to have focus for scanning) #MyGUI.overrideredirect(1) #Doing it this way works but disable until working on small screen, this just sets window as fullscreen #MyGUI.attributes('-fullscreen', True) #Set window to resolution of screen 800x420 pixels MyGUI.geometry('800x420') #Set window title (Perhaps later remove title bar if possible) MyGUI.title('Island Walk Tracker') #Set window background colour to black MyGUI.configure(background='black') ##GLOBAL VARIABLES ## #Create variable for RFID code global RFIDcode RFIDcode = '' #Create variable for checkpoint number global checkpoint_number checkpoint_number = 2 #Create variable for photo filepath global photo_path photo_path = '' ## DECLARE ALL TKINTER VARIABLES ## #Declare like this for a tkinter variable to update dynamically on GUI (A global var will not do this) rfid_codeTK = StringVar() rfid_codeTK.set('') walk_numberTK = IntVar() walk_numberTK.set(0) fullnameTK = StringVar() fullnameTK.set('') classTK = StringVar() classTK.set('') ## DEFINE LABELS AND HOW/WHERE THEY APPEAR ON THE SCREEN ## #USE 'textvariable' instead of text for labels below to link to a live variable (See info here http://www.tutorialspoint.com/python/tk_label.htm) #Spacer label just adds blank label of fixed width to set width of column and space down one row from top of page lblSpacer = Label (text = ' ',fg='white',bg='black',font = 'Helvetica 8 bold') lblSpacer.grid(row=0,column=0) #TEST CODE: Display variable RFIDcode in a label for testing. Comment out to hide rfid code. #lblRFID = Label (MyGUI,textvariable = rfid_codeTK ,fg='white',bg='black',font = 'Helvetica 20 bold') #lblRFID.grid(row=3,column=1) #Display Walk number in a label lblWalkNumber = Label(MyGUI,textvariable = walk_numberTK ,fg='white',bg='black',font = 'Helvetica 115 bold') #Unlike other TK variables this is not placed in grid until after scan as this stops a big '0' appearing on screen #lblWalkNumber.grid(row=2,column=0) #Display Walker name in a label lblWalkerName = Label (MyGUI,textvariable = fullnameTK ,fg='white',bg='black',font = 'Helvetica 25 bold') lblWalkerName.grid(row=3,column=0) #Display class in a label lblWalkerClass = Label(MyGUI,textvariable = classTK ,fg='white',bg='black',font = 'Helvetica 25 bold') lblWalkerClass.grid(row=4,column=0) #Display photo on the screen #TEST CODE: later on change 'Blank' for the field in database that represents Student_ID #photo_path = 'WALK_PHOTOS/'+ 'Blank' +'.gif' #pic = PhotoImage(file= photo_path ) #ImgWalkerPhoto = Label(MyGUI,image = pic) #ImgWalkerPhoto.grid(row=2,column=1) ## EVENT OCCURS WHEN RFID CODE IS ENTERED (following 'enter' keypress) ## def Update_Walker_Screen(event): global RFIDcode global photo_path global checkpoint_number #Search database for matching RFIDcode from localdb and SELECT all data from that row lcur.execute("SELECT walk_number, forename, surname, class, student_id FROM walkers WHERE rfid_code = '"+ RFIDcode +"'") row = lcur.fetchall() ## SET POSITIONS OF THINGS ON THE TKINTER FORM ## #Display walker number in its label (done here after the scan event as if done above with other TK variables a big '0' appears on screen because it is an int so has a '0' not null value when initialised. lblWalkNumber.grid(row=2,column=0) pic = PhotoImage(file='WALK_PHOTOS/'+ 'Blank' +'.gif') ImgWalkerPhoto = Label(MyGUI,image = pic) #Hide image for testing #ImgWalkerPhoto.grid(row=2,column=1) ## SET VARIABLES TO DISPLAY ON SCREEN (WILL AUTO UPDATE SCREEN WHEN TK VARIABLES CHANGE) ## #Set rfid_codeTK variable to be RFIDcode from the code entered from scan. rfid_codeTK.set(RFIDcode) #Set walk_numberTK variable to be walk_number from the fetched database record walk_numberTK.set(row[0][0]) #Set fullnameTK variable to be forename + surname from the fetched database record fullnameTK.set(row[0][1] + ' ' + row[0][2]) #Set classTK variable to be class from the fetched database record classTK.set(row[0][3]) #Display photo on the screen after scan photo_path = 'WALK_PHOTOS/'+ row[0][4] +'.gif' if os.path.isfile(photo_path) == True: #show photo with filename as photo_path = 'WALK_PHOTOS/'+ row[0][4] +'.gif' else: #show blank photo photo_path = 'WALK_PHOTOS/Blank.gif' #Display image #ImgWalkerPhoto.grid(row=2,column=1) #This should update screen items (does flash picture up but not sure if its any use) #MyGUI.update_idletasks() #Look up current time walkers_time = datetime.datetime.now().strftime("%H:%M:%S") #Log time into database in correct checkpoint column if checkpoint_number == 1: #sqlquery = """INSERT INTO walkers('ckpt_1') VALUES({0})""".format(json.dumps(walkers_time)) #lcur.execute("INSERT INTO walkers('ckpt_1') VALUES () print('Checkpoint 1 selected') elif checkpoint_number == 2: sqlquery = "INSERT INTO walkers('ckpt_1') VALUES({0})".format(json.dumps(walkers_time)) print(sqlquery) print('Checkpoint 2 selected') elif checkpoint_number == 3: print('Checkpoint 3 selected') elif checkpoint_number == 4: print('Checkpoint 4 selected') elif checkpoint_number == 5: print('Checkpoint 5 selected') elif checkpoint_number == 6: print('Checkpoint 6 selected') elif checkpoint_number == 7: print('Checkpoint 7 selected') elif checkpoint_number == 8: print('Checkpoint 8 selected') elif checkpoint_number == 9: print('Checkpoint 9 selected') elif checkpoint_number == 10: print('Checkpoint 10 selected') elif checkpoint_number == 11: print('Checkpoint 11 selected') elif checkpoint_number == 12: print('Checkpoint 12 selected') else: #Checkpoint not correctly selected so ask them to restart and select a new checkpoint number print('Please select a checkpoint number') #Write the scanned walker details into text file ready to email. If file does not exist then create it, else append to existing file. #file = open('emaildata.txt', 'a') with open('emaildata.txt', 'a') as myfile: myfile.write(str(row[0][0]) + ',' + str(walkers_time) + ',' + 'Y' + '|')#walk_numberTK.get()) #Clear global variable RFIDcode ready for next scan. RFIDcode = '' #This function detects any keypresses and then adds them intothe RFIDcode global string variable #(Ignores Enter key as thats handled earlier in code so never reaches it. Add extra ignores if needed above.) def keypress(event): global RFIDcode RFIDcode = RFIDcode + str(event.char) #Bind any key press to run the keypress function. MyGUI.bind('<Key>',keypress) #Bind an 'Enter' key press to run the Update_Walker_Screen function. MyGUI.bind('<Return>',Update_Walker_Screen) MyGUI.mainloop()