Using Windows Batch File (.bat) for executing QGIS Python program without opening QGIS Software

Question

I have a Python Program for doing some geoprocessing in QGIS. The starting of the Python program is given below.

import sys
from qgis.core import *
import qgis.utils
from qgis.gui import *
from PyQt4.QtGui import *
from PyQt4.QtCore import Qt
from qgis.core import QgsApplication
from PyQt4.QtGui import QApplication
QgsApplication.setPrefixPath("C:/OSGeo4W/apps/qgis", True)
QgsApplication.initQgis()
sys.path.append('C:/OSGeo4W/apps/qgis/plugins')
from processing.core.Processing import Processing
Processing.initialize()
from processing.tools import *
from PyQt4.QtCore import QFileInfo
import processing
import os
import ogr
from osgeo import ogr, gdal
import math
import xlrd

..............................many other lines.................

I want to execute this python program from a Windows Batch File, that is .bat file; even without opening QGIS software.

For that, I created a .bat file as given below.

SET QGIS_PREFIX_PATH=C:\OSGeo4W\apps\qgis
call "C:/OSGeo4W/bin/o4w_env.bat"
SET PYTHONPATH=C:\OSGeo4W\apps\qgis\python;%PYTHONPATH%
SET PATH=%PATH%;C:\OSGeo4W\apps\qgis\bin

cmd /c python "C:/Users/Sreeraj/.qgis2/processing/scripts/Task3.py" 

Unfortunately, when I am executing this .bat file, in C:\WINDOWS\system32\cmd.exe , I am getting an error:

python.exe has stopped working 
A problem caused the program to stop working correctly. 
Windows will close the program and notify you if a solution is available.  

What modification do I have to make in .bat file or in my Python program, in order to solve this issue ?

Answer 1

I found the issue and solved it. Actually, the issue was with the line (in the python script) :

sys.path.append('C:/OSGeo4W/apps/qgis/plugins')

The 'processing' functionalities will be stored in the location C:/OSGeo4W/apps/qgis/python/plugins and not in C:/OSGeo4W/apps/qgis/plugins . But, the other core plugins will be stored in the location C:/OSGeo4W/apps/qgis/plugins .

So, for solving this issue, I have changed the line :

sys.path.append('C:/OSGeo4W/apps/qgis/plugins')

as :

sys.path.append('C:/OSGeo4W/apps/qgis/python/plugins') .

This is the simple solution for this tricky error.

Answer 2

I tried for long and found the following points are important

1. Always use the OSGEO4W-Shell to execute an osgeo-program, don't use cmd.exe directly. (The shell executes all batch files in %OSGEO4W_ROOT%/etc/ini where a lot of environment variables are set)

2. To start python with full qgis support, so you can run standalone python qgis apps, use the following environment settings:

   SET QGIS_PREFIX_PATH=%OSGEO4W_ROOT:\=/%/apps/qgis SET PYTHONPATH=%OSGEO4W_ROOT%\apps\qgis\python SET PYTHONHOME=%OSGEO4W_ROOT%\apps\Python27 SET PATH=%PATH%;%OSGEO4W_ROOT%\apps\Python27\Scripts;%OSGEO4W_ROOT%\apps\qgis\bin

most of it you have already set, but mine is slightly different, as you can see. Plus the batch-files called by the osgeo4w-shell fill the %PATH% correctly.