I write a script by Python as a reminder, and want it to run every half an hour. So I use crontab to complete the task.
0,30 * * * * /path/to/reminder.py
but it did not work.
I want to know what the problem is. So change it to
0,30 * * * * /path/to/reminder.py 2> /path/to/err
and I got it
GtkWarning: could not open display
The problem was that cron has not the environment variable DISPLAY.
The way is to set it on the script
import os os.environ['DISPLAY'] = ':0.0'
and problem solved.