This file describes the command line arguments which can be passed during installation of the RNetCDF package and gives some further hints. Software Requirements ===================== NetCDF library version 4.1.3 or greater. UDUNITS library version 2.0.4 or greater (optional, for calendar functions). On platforms that support both 32- and 64-bit executables, ensure that the above libraries and the R executable are compatible. Mixing 32-bit and 64-bit software will generally not work. R CMD INSTALL Options ===================== Libraries and include files are usually detected automatically by nc-config, which is part of most netcdf4 installations. If this causes problems, you can disable nc-config using --without-nc-config. The configure script can accept variables to define extra paths or libraries: CPPFLAGS='-I [-I ...]' extra directories of header files LDFLAGS='-L [-L ...]' extra directories for libraries LIBS='-l [-l ...]' libraries to link Definitions for the above variables may be appended to the configure command line. Note that libraries may be specified in LIBS in a few different ways. The most common way is '-l' as shown above, and the compiler will typically search for a library called lib.so and then lib.a. But you can also specify the full pathname of a library if necessary, perhaps to force the use of a particular netcdf or udunits library on systems with multiple versions available. R CMD INSTALL Example ===================== R CMD INSTALL --configure-args="CPPFLAGS=-I/sw/include \ LDFLAGS=-L/sw/lib LIBS=-lhdf5" RNetCDF_2.5-2.tar.gz LD_LIBRARY_PATH =============== If a runtime error occurs indicating that shared libraries cannot be found, you may need to set or modify the library search path to include directories where NetCDF, HDF5 and/or UDUNITS libraries are stored. This is sometimes necessary for custom installations of the libraries. The library search path is typically influenced by the environment variable LD_LIBRARY_PATH (or DYLD_LIBRARY_PATH for Mac OSX). For example: export LD_LIBRARY_PATH=/sw/lib:$LD_LIBRARY_PATH On some systems, it is possible to build R packages so that dependencies are found automatically at runtime. For example, some linkers provide an option such as '-rpath', which embeds the library search path when creating an executable or shared library. It may also be possible to avoid runtime dependencies by building your R package against static libraries (*.a), but this will only work if the functions in the libraries were compiled as position independent code (e.g. using the -fPIC option of gcc). R CMD check Example =================== R CMD check --install-args="--configure-args='CPPFLAGS=-I/sw/include \ LDFLAGS=-L/sw/lib'" RNetCDF_2.5-2.tar.gz Time units ========== Common udunits databases are distributed with RNetCDF, and these are used by default when RNetCDF is loaded by R. However, a different units database may be used by specifying the appropriate file in environment variable UDUNITS2_XML_PATH.