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For a single user, grib_api might be installed in your home directory. For a multi-user environment, say a cluster or High Performance Computing Facility (HPCF), we suggest installing the grib_api package centrally once only is probably best and pointing your build configuration to this location.

In the walk-through example that follows, we assume a single-user download and install is assumed.

Download and unpack

In this example, we assume you have created create a directory called $HOME/ecmwf in which you will download and compile grib_apigrib-api will be downloaded and compiled.

If you haven't already obtained the grib_api package, get it from the grib-api web site.

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mkdir bld
mkdir grib-api
cd bld
export CC=gcc
export FC=gfortran
cmake ../grib_api-1.14.0-Source   \
      -DCMAKE_BUILD_TYPE=Bit          \
      -DCMAKE_INSTALL_PREFIX="../grib-api"   \
      -DENABLE_NETCDF=ON              \
      -DENABLE_JPG=OFF                \
      -DENABLE_PNG=OFF                \
      -DENABLE_PYTHON=ON              \
      -DENABLE_FORTRAN=ON             \
      -DENABLE_GRIB_THREADS=ON

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Available options

To get additional help on the available options (similar to the 'configure --help' command) run the command:

cmake -LH grib_api-1.14.0-Source

Configuring using configure

Grib_api compilation can also be made using the GNU configure tool to ease building and compilation. It is tested on different platforms and compilers and should not cause any problems. If however, you do have a problem installing grib_api, please email: openifs-support@ecmwf.int.

Other build types

CMake supports several standard 'build types'. These are:

Available options

To get additional help on the available options (similar to the 'configure --help' command) run the command:

cmake -LH grib_api-1.14.0-Source

Configuring using configure

Grib_api compilation can also be made using the GNU configure tool.

The configure The configure command is contained in the grib_api directory you have just unpacked. We will use the command with a . A few options are needed to suit OpenIFS and assume we'll use the gcc & gfortran compilers are assumed in the example below. If you use different compilers, see below.

cd grib_api_1.914.180-Source
./configure --prefix=$HOME/ecmwf/grib_api --enable-pthread --enable-python --disable-jpeg

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A quick description of what these options are for:

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grib_api will build both shared and static libraries by default. Shared libraries may need to be built if the python interface is used, depending on your installation.

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By default, cmake and configure will use the preferred compiler and set appropriate compiler options accordingly (for cmake, this depends on the build type).

(by searching your PATH environment variable). This may not be what you need if you have multiple compilers available . As in and want to direct cmake/configure to the most appropriate one to use. In the above example, we enforce the use of the GNU C and Fortran compilers (as this is the default compiler for OpenIFS). If you intend to use other compilers with OpenIFS you will need to set these appropriately.

Recommended options are conservative to ensure stability and bit-reproducibility. The cmake and configure commands usually chooses choose a sensible set of optimized compiler flags for the choice of supported compiler .for the 'Bit' build type.

Although it is not normally necessary to specify them, the The following examples show the recommended compiler options and how to set them for the cmake and configure commands.

For the IBM xlc compiler we recommend disabling the creation of 'shared libraries' which is known to cause problems with some versions of grib_api.

export CC=gcc
export FC=gfortran
export CCFLAGS="-g -O2"
export FCFLAGS="-g -O2"

export CC=icc
export FC=ifort
export CFLAGS="-g -O1 -fp-model precise"
export FCFLAGS="-g -O1 -fp-model precise"

export CC=cc
export FC=ftn
export CFLAGS="-O1 -G2 -hflex_mp=conservative -hadd_paren -hfp1"
export FCFLAGS="-O1 -G2

 -hflex_mp=conservative -hadd_paren -hfp1"

export CC=xlc_r
export FC=xlf90_r
export CFLAGS="-g -O2 -qstrict -qarch=auto -qtune=auto"
export FCFLAGS="-g -O2 -qstrict -qarch=auto -qtune=auto"

export CC=

gcc
export FC=

gfortran
cmake .... -DCMAKE_C_FLAGS="-g -O2"

 -DCMAKE_Fortran_FLAGS="-g -O2"

export CC

=icc
export FC=ifort
export CFLAGS="-g -

O1 -fp-model precise"
export FCFLAGS="-g -O1 -fp-model precise"

Compiling, checks and installing

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