Building the NetCDF-4.2 and later Fortran libraries

[TOC]

In versions before 4.2, the Fortran netCDF library source was bundled with the C library source in one distribution, and it was possible to combine the libraries in a single library file. With version 4.2, the Fortran netCDF library for Fortran77 and Fortran90 APIs has been separated into its own source distribution, and should now be built as a separate library, after the C library is built and installed. This separation simplifies the building and use of the C and Fortran netCDF libraries and allows them to evolve independently.

Please note that in the example commands below, we assume use of a POSIX-standard shell, such as sh, bash, ksh, or zsh. If you are using csh instead, you will have to use the

   setenv ENV_VARIABLE  value

syntax to set environment variables instead of the

   ENV_VARIABLE=value

syntax used in the examples that use a POSIX-standard shell. In either case, ${DIR1} is the value of the environment variable DIR1.

It will be easier to build the netCDF Fortran library if the C (and if needed, HDF5) libraries are built as shared libraries (the default), but you can also use static libraries, as described in a later section.

Building with shared libraries

First make sure the netCDF C library has been built, tested, and installed under directory ${DIR1}, as specified by --prefix=${DIR1} to the C library configure script, or under directory /usr/local by default.
For the Fortran netCDF library, use the same C compiler as used to create the netCDF C library, specified with the CC environment variable, if necessary.
If the netCDF C library was installed as a shared library in a location that is not searched by default, you will need to set the LD_LIBRARY_PATH environment variable (or DYLD_LIBRARY_PATH on OSX) to specify that directory before running the configure script, for example:
```
export LD_LIBRARY_PATH=${DIR1}/lib:${LD_LIBRARY_PATH}
```
If you set the LD_LIBRARY_PATH (or DYLD_LIBRARY_PATH) environment variable in the previous step, don't use the "sudo" command before the following "configure" or "make check" commands. Using "sudo" causes the LD_* environment variables to be ignored, as a security precaution. You can use "sudo make install" as the last step, but you shouldn't need to use "sudo" before that.
For the configure script, set CPPFLAGS and LDFLAGS variables to specify the include and lib directories for the netCDF C library. For example, to install the Fortran libraries in the same directory ${DIR1} where the C netCDF library is installed:
```
  CPPFLAGS=-I${DIR1}/include LDFLAGS=-L${DIR1}/lib ./configure --prefix=${DIR1}
```
If you are cross-compiling, you should also include the configure option "--disable-fortran-type-check", as in:
```
  CPPFLAGS=-I${DIR1}/include LDFLAGS=-L${DIR1}/lib \
    ./configure --disable-fortran-type-check --prefix=${DIR1}
```
If that succeeds, run "make check".
If that succeeds, run "make install" or "sudo make install".

Building with static libraries

If you can't build the C netCDF library as a shared library or if it has already been installed by someone else only as a static library (which means there are no libnetcdf.so files in the library directory where the netCDF C library was installed), then building and installing the Fortran netCDF libraries will be somewhat more complicated.

If you need to set the LD_LIBRARY_PATH (or DYLD_LIBRARY_PATH) environment variable, don't use the "sudo" command before the following "configure" or "make check" commands. Using "sudo" causes the LD_* environment variables to be ignored. You can use "sudo make install" as the last step, but you shouldn't need to use "sudo" before that.

Assume the static netCDF C library is installed under ${DIR1}, and the other needed shared libraries for HDF5, zlib, and curl are installed under ${DIR2} (which might be the same as ${DIR1}).
Use the same C compiler as used to create the netCDF C library, specified with the CC environment variable, if necessary.
Set the CPPFLAGS, LDFLAGS, and LD_LIBRARY_PATH environment variables to specify where the netCDF C library is installed and where the other shared libraries may be found, before running the configure script. For example:
```
  CPPFLAGS="-I${DIR1}/include -I${DIR2}/include" \
  LD_LIBRARY_PATH=${DIR1}/lib:${DIR2}/lib:${LD_LIBRARY_PATH} \
  LDFLAGS="-L${DIR1}/lib -L${DIR2}/lib" \
  LIBS="-lnetcdf -lhdf5_hl -lhdf5 -lz -lcurl" \
  ./configure --disable-shared --prefix=${DIR1}
```
If you are cross-compiling, you should also include the configure option "--disable-fortran-type-check".
For parallel I/O: The configure script sets CFLAGS appropriately for standard compilers, but if you are building with parallel I/O using wrappers such as mpicc and mpif90, you sometimes have to set CFLAGS to indicate which Fortran compiler is wrapped by mpif90. For example, if "mpicc --show" and "mpif90 --show" indicate gcc and gfortran are being used, then set CFLAGS=-DgFortran, and similarly set CFLAGS=-DpgiFortran for Portland Group compilers.
If that succeeds, run "make check".
If that succeeds, run "make install" or "sudo make install".

Linking your programs with netCDF Fortran libraries

If you built the shared libraries, you can link with something like

   fortran_compiler my_prog.f -o my_prog -I${DIR1}/include -L${DIR1}/lib -lnetcdff

to link your Fortran software with the installed netCDF Fortran and C libraries. If you didn't install the shared libraries in a standard place, you may need to set LD_LIBRARY_PATH (or DYLD_LIBRARY_PATH for OSX) before running the resulting program.

If you built static libraries, you will need to use something like

   fortran_compiler my_prog.f -o my_prog -I${DIR1}/include \
    -L${DIR1}/lib -lnetcdff -lnetcdf -L${DIR2}/lib -lhdf5_hl -lhdf5 -lz -lcurl -lm

to link Fortran software with the installed Fortran library and the libraries on which it depends.

A simpler alternative that should work for either shared or static libraries is to use the "nf-config" utility installed in ${DIR1}/bin:

   `nf-config --fc` my_prog.f -o my_prog `nf-config --fflags --flibs`

or the more general "pkg-config" utility, if you have it:

   fortran_compiler my_prog.f -o my_prog `pkg-config --cflags --libs netcdf-fortran`

Specifying The Environment for Building

The netCDF configure script searches your path to find the compilers and tools it needed. To use compilers that can't be found in your path, set their environment variables.

The configure script will use gcc and associated GNU tools if they are found. Many users, especially those with performance concerns, will wish to use a vendor supplied compiler.

For example, on an AIX system, users may wish to use xlc (the AIX compiler) in one of its many flavors. Set environment variables before the build to achieve this.

For example, to change the C compiler, set CC to xlc (in sh: export CC=xlc). (But don't forget to also set CXX to xlC, or else configure will try to use g++, the GNU C++ compiler to build the netCDF C++ API. Similarly set FC to xlf90 so that the Fortran APIs are built properly.)

By default, the netCDF library is built with assertions turned on. If you wish to turn off assertions, set CPPFLAGS to -DNDEBUG (csh ex: setenv CPPFLAGS -DNDEBUG).

If GNU compilers are used, the configure script sets CPPFLAGS to “-g -O2”. If this is not desired, set CPPFLAGS to nothing, or to whatever other value you wish to use, before running configure.

For cross-compiles, the following environment variables can be used to override the default fortran/C type settings like this (in sh):

 export NCBYTE_T=''integer(selected_int_kind(2))''
 export NCSHORT_T=''integer*2''
 export NF_INT1_T=''integer(selected_int_kind(2))''
 export NF_INT2_T=''integer*2''
 export NF_INT1_IS_C_SHORT=1
 export NF_INT2_IS_C_SHORT=1
 export NF_INT_IS_C_INT=1
 export NF_REAL_IS_C_FLOAT=1
 export NF_DOUBLEPRECISION_IS_C_DOUBLE=1

In this case you will need to run configure with –disable-fortran-compiler-check and –disable-fortran-type-check.

Variable Description Notes

Variable	Usage	Description
CC	C compiler	If you don't specify this, the configure script will try to find a suitable C compiler. The default choice is gcc. If you wish to use a vendor compiler you must set CC to that compiler, and set other environment variables (as described below) to appropriate settings.
FC	Fortran compiler (if any)	If you don't specify this, the configure script will try to find a suitable Fortran and Fortran 77 compiler. Set FC to "" explicitly, or provide the –disable-f77 option to configure, if no Fortran interface (neither F90 nor F77) is desired. Use –disable-f90 to disable the netCDF Fortran 90 API, but build the netCDF Fortran 77 API.
F77	Fortran 77 compiler (if any)	Only specify this if your platform explicitly needs a different Fortran 77 compiler. Otherwise use FC to specify the Fortran compiler. If you don't specify this, the configure script will try to find a suitable Fortran compiler. For vendor compilers, make sure you're using the same vendor's Fortran 90 compiler. Using Fortran compilers from different vendors, or mixing vendor compilers with g77, the GNU F77 compiler, is not supported and may not work.
CXX	C++ compiler	If you don't specify this, the configure script will try to find a suitable C++ compiler. Set CXX to "" explicitly, or use the –disable-cxx configure option, if no C++ interface is desired. If using a vendor C++ compiler, use that vendor's C compiler to compile the C interface. Using different vendor compilers for C and C++ may not work.
CFLAGS	C compiler flags	"-O" or "-g", for example.
CPPFLAGS	C preprocessor options	"-DNDEBUG" to omit assertion checks, for example.
FCFLAGS	Fortran 90 compiler flags	"-O" or "-g", for example. These flags will be used for FORTRAN 90. If setting these you may also need to set FFLAGS for the FORTRAN 77 test programs.
FFLAGS	Fortran 77 compiler flags	"-O" or "-g", for example. If you need to pass the same arguments to the FORTRAN 90 build, also set FCFLAGS.
CXXFLAGS	C++ compiler flags	"-O" or "-g", for example.
ARFLAGS, NMFLAGS, FPP, M4FLAGS, LIBS, FLIBS, FLDFLAGS	Miscellaneous	One or more of these were needed for some platforms, as specified below. Unless specified, you should not set these environment variables, because that may interfere with the configure script.

11 KiB Raw Blame History Unescape Escape