netcdf-c/docs/install-fortran.md

Building the NetCDF-4.2 and later Fortran libraries {#building_netcdf_fortran}
===================================================

[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, <I>${DIR1}</I> is the value of the environment variable <I>DIR1</I>.

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 {#building_fortran_shared_libraries}
==============================

1.  First make sure the netCDF C library has been built, tested, and
    installed under directory <I>${DIR1}</I>, as specified by
    --prefix=<I>${DIR1}</I> to the C library configure script, or under
    directory /usr/local by default.
2.  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.
3.  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}

4.  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.
5.  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}

6.  If that succeeds, run "make check".
7.  If that succeeds, run "make install" or "sudo make install".

Building with static libraries {#building_fortran_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.

1.  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}*).
2.  Use the same C compiler as used to create the netCDF C library,
    specified with the CC environment variable, if necessary.
3.  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".

4.  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.
5.  If that succeeds, run "make check".
6.  If that succeeds, run "make install" or "sudo make install".

Linking your programs with netCDF Fortran libraries {#linking_against_netcdf_fortran}
==============================

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`