To install the lastest stable QGIS and GRASS 6 I use:
sudo apt-get install python-software-properties
sudo add-apt-repository 'deb http://qgis.org/debian trusty main'
gpg --keyserver keyserver.ubuntu.com --recv DD45F6C3
gpg --export --armor DD45F6C3 | sudo apt-key add -
sudo apt-get update
sudo apt-get install qgis python-qgis qgis-plugin-grass grass-gui grass-doc
The keycodes are taken from the QGIS page. You'll then need to turn on the GRASS plugin in the QGIS plugins menu. You can wrap this up in an install script so each time you have a fresh install you can run the script you wrote previously, an example of my own is here.
If you are running a 64-bit machine, make sure that you are installing QGIS from the 64-bit network installer: http://download.osgeo.org/osgeo4w/osgeo4w-setup-x86_64.exe.
I am an OSGeo4W user, for both Windows 64 and 32 bit.
And I must say that the installation made from the network installer seems to me pretty stable. I don't see another reason for the stand-alone installer more than for a Portable GIS.
The standard installation was made only once, and all I do is keep it updated from the advanced mode.
When a tool does not work, 90% of the time is due to a problem with the data or the procedure used.
There is no need to install outdated packages, they will surely not solve the problem and they are even likely to generate some more. When a regression in a package is found, it is reported to the developers and (earlier than later) it is fixed.
These are my current packages for a qgis, grass and saga search in a Win10 64bit machine:
This is the QGIS Settings > Options > System view:
This is the C:\OSGeo4W64\bin\qgis-grass7.bat content:
@echo off
call "%~dp0\o4w_env.bat"
call "%OSGEO4W_ROOT%\apps\grass\grass-7.6.0\etc\env.bat"
call qt5_env.bat
call py3_env.bat
@echo off
path %OSGEO4W_ROOT%\apps\qgis\bin;%OSGEO4W_ROOT%\apps\grass\grass-7.6.0\lib;%OSGEO4W_ROOT%\apps\grass\grass-7.6.0\bin;%PATH%
set QGIS_PREFIX_PATH=%OSGEO4W_ROOT:\=/%/apps/qgis
set GDAL_FILENAME_IS_UTF8=YES
rem Set VSI cache to be used as buffer, see #6448
set VSI_CACHE=TRUE
set VSI_CACHE_SIZE=1000000
set QT_PLUGIN_PATH=%OSGEO4W_ROOT%\apps\qgis\qtplugins;%OSGEO4W_ROOT%\apps\qt5\plugins
start "QGIS" /B "%OSGEO4W_ROOT%\bin\qgis-bin-g7.exe" %*
This is the C:\OSGeo4W64\bin\o4w_env.bat content:
REM Make parent of this script location our current directory,
REM converting UNC path to drive letter if needed
pushd %~dp0
cd ..
REM set OSGEO4W_ROOT to short path version
for %%i in ("%CD%") do set OSGEO4W_ROOT=%%~fsi
REM start with clean path
set path=%OSGEO4W_ROOT%\bin;%WINDIR%\system32;%WINDIR%;%WINDIR%\system32\WBem
for %%f in ("%OSGEO4W_ROOT%\etc\ini\*.bat") do call "%%f"
popd
And this is the C:\OSGeo4W64\bin\qgis-bin-g7.env content:
PATH=C:\OSGEO4~1\apps\qgis\bin;C:\OSGEO4~1\apps\grass\grass-7.6.0\lib;C:\OSGEO4~1\apps\grass\grass-7.6.0\bin;C:\OSGEO4~1\apps\Python37;C:\OSGEO4~1\apps\Python37\Scripts;C:\OSGEO4~1\apps\qt5\bin;{app};C:\Program Files\MiKTeX 2.9\miktex\bin;C:\OSGEO4~1\apps\Python27\Scripts;C:\OSGEO4~1\bin;C:\WINDOWS\system32;C:\WINDOWS;C:\WINDOWS\system32\WBem;C:\Program Files\R\R-3.5.2\bin\x64
GDAL_DATA=C:\OSGEO4~1\share\gdal
GDAL_DRIVER_PATH=C:\OSGEO4~1\bin\gdalplugins
GDAL_FILENAME_IS_UTF8=YES
GEOTIFF_CSV=C:\OSGEO4~1\share\epsg_csv
GISBASE=C:\OSGEO4~1\apps\grass\grass-7.6.0
GRASS_PROJSHARE=C:\OSGEO4~1\share\proj
GRASS_PYTHON=C:\OSGEO4~1\bin\python.exe
JPEGMEM=1000000
OSGEO4W_ROOT=C:\OSGEO4~1
PROJ_LIB=C:\OSGEO4~1\share\proj
PYTHONHOME=C:\OSGEO4~1\apps\Python37
QGIS_PREFIX_PATH=C:/OSGEO4~1/apps/qgis
QT_PLUGIN_PATH=C:\OSGEO4~1\apps\qgis\qtplugins;C:\OSGEO4~1\apps\qt5\plugins
QT_RASTER_CLIP_LIMIT=4096
VSI_CACHE=TRUE
VSI_CACHE_SIZE=1000000
O4W_QT_PREFIX=C:/OSGEO4~1/apps/Qt5
O4W_QT_BINARIES=C:/OSGEO4~1/apps/Qt5/bin
O4W_QT_PLUGINS=C:/OSGEO4~1/apps/Qt5/plugins
O4W_QT_LIBRARIES=C:/OSGEO4~1/apps/Qt5/lib
O4W_QT_TRANSLATIONS=C:/OSGEO4~1/apps/Qt5/translations
O4W_QT_HEADERS=C:/OSGEO4~1/apps/Qt5/include
Reference links
Best Answer
In order to have grass acces using the OSgeo4w installer in windows you must use the express desktop install option. The other two options do install Qgis but you will not have a grass plugin (at least in my experience). Once the installation is finished you will have in the OSgeo4w menu folder
Qgis browser
Qgis browser with Grass 6.43
Qgis Desktop 2.12.0
Qgis Desktop 2.12.0 with grass 6.43
If you want to work with Grass you have to choose Qgis Desktop 2.12.0 with grass 6.43 Once the program is open you must check in Plugins/manage and install plugins/installed that the grass6 plugin is present and that is checked for use.
Now open the browser panel and also Grass tools panel in View/panels/. In the browser panel navigate to your map set folder right click on it and choose "open map set".
Now you can add layers by double clicking on them. Once the map set folder is open and have some layers displayed you can work with Grass with the Grass Tools panel that we activated before.