To use WRF model in WRF4G2.0 you have to configure app variable in the experiment.wrf4g file.
app: This is to define applications with the following format tag | type | value (advanced configuration):
tag: Name identifier. wrf_all_in_one tag is a special name that indicates which is a bundle that includes WRFV3 and WPS files, netcdf, ncos cdos and openmpi libraries. type: Either bundle or command. value: If type is bundle indicates the path of the bundle that can have the following formats zip, tar, tar.gz (or tgz), and tar.bz2 (or tbz2). If type is command, you can type shell commands to configure netcdf, openmpi or WRF.