Crontab not executing Python script on Ubuntu

Question

I have a Python script with the following code:

import subprocess
import sys

default = "Take a 20 second break - look at least 20 feet away!"
message = sys.argv[1] if len(sys.argv) > 1 else default

def sendmessage(message):
    subprocess.Popen(['notify-send', message])
    return

sendmessage(message)

called takebreak.py , which will send a system notification.

When I try to automate it using crontab like so:

* * * * * /usr/bin/python /home/polo/git-repositories/takebreak/takebreak.py

It doesn't work. Running the command

/usr/bin/python /home/polo/git-repositories/takebreak/takebreak.py

in the terminal does work, which means it's not a file location problem, but rather something to do with cron . Any ideas?

EDIT1:

After debugging and looking at the logs, I can verify that cron is actually executing the commmand export DISPLAY=:0; /usr/bin/python /home/polo/git-repositories/takebreak/takebreak.py export DISPLAY=:0; /usr/bin/python /home/polo/git-repositories/takebreak/takebreak.py every minute like I set it to do, but for some reason this command, while it should send a system notification, is not doing so. Any ideas?

EDIT2:

The solution was to add some address bus thing (forget the exact code) that I found in another post, that ended up fixing it. Unfortunately, none of the answers or comments here helped with solving the problem, but thanks regardless!

Answer 1

Most likely, the problem is that notify-send is not in your $PATH when running from crontab . First, figure out where it's stored:

$ which notify-send
/usr/bin/notify-send

For me, it's in /usr/bin .

At the top of your crontab file ( crontab -e ), set $PATH :

PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

If you want to include whatever $PATH may have already been set before (safer), do this instead:

PATH="${PATH}:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

Make sure this includes the directory where your command is installed, if it's not installed in /usr/bin .

Of course, the other option, is to simply specify the full command path in your Python script:

subprocess.Popen(['/usr/bin/notify-send', message])