I am trying to install rgdal on a Linux cluster, but am running into some issues. I have successfully installed gdal and proj4, but when I try to build rgdal, I receive the message that "proj_api.h not found in standard or given locations". proj_api.h is located at /bin/proj4/include/proj_api.h. I have added the path to $PATH, however I still can't compile it.
How can I specify the path so that I can install rgdal?