Error: QGIS standalone script in crontab

Question

I am trying to automate QGIS (2.18.4) standalone scripts in ubuntu using crontab. My scripts execute well when running from command, but fail if I put in crontab.

from qgis.core import *
from PyQt4.QtGui import *
from PyQt4.QtCore import *
from qgis.gui import *
app = QApplication([])
QgsApplication.setPrefixPath("/usr", True)
QgsApplication.initQgis()

In crontab, it fails at app = QApplication([]). Crontab gives error as

: cannot connect to X server

How to make my QGIS standalone script run in crontab?

Answer 1

This problem is actually not related to this community, you should ask in unix.stackexchange.com to get better answers.

To run a GUI command with a cronjob, you'll have to tell cron what display the program should use:

export DISPLAY=:0

:0 is the default Display. If you like the program to run on other display, please change the number accordingly (e.g. :1, :2, etc).

Your cron command will look like this:

* * * * * export DISPLAY=:0 && python /path/to/your/command.py