@reboot cronjob not executing

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http://stackoverflow.com – I have a Python script which simply writes some text and saves it to a file #! /usr/bin/python3 def main(): filename = '/home/user/testHello.txt' openfile = open(filename,"w") print("Hello CRON", file = openfile) if __name__ == "__main__": main(); I want to execute this script at startup via CRON. So I edit the crontab listing by using >crontab -e Next I add : @reboot /home/user/tester.py This is the location of the file, and the file has permissions to execute. I can run the file no problem as a script from the commandline. Yet when I restart the machine, no (HowTos)