/*! \file
Documentation for getting and building netCDF

\page getting Getting NetCDF

The easiest way to get netCDF is through a package management program,
such as rpm, yum, adept, and others. NetCDF is available from many
different repositories, including the default Red Hat and Ubuntu
repositories.

When getting netCDF from a software repository, you will wish to get
the development version of the package ("netcdf-devel"). This includes
the netcdf.h header file.

Unfortunately, you may not be able to get a recent version of netCDF
from a package management system, in which case you must build from
source code. Get the <a
href=ftp://ftp.unidata.ucar.edu/pub/netcdf/netcdf.tar.gz>source
distribution for the latest full release</a>. It is the latest,
fully-tested release.

Alternatively, you may wish to try the <a
href=ftp://ftp.unidata.ucar.edu/pub/netcdf/snapshot/netcdf-4-daily.tar.gz>daily
snapshot</a>. It is generated nightly at the Unidata Program
Center. It has passed all tests on our (Linux) test machine, but not
necessarily all platform compatibility tests.

\warning The daily snapshot release contains bug-fixes and new features
added since the last full release. It may also contain portability
bugs.

Once you have downloaded and unpacked the distribution, see \ref
building.

\page building Building NetCDF

The netCDF-C library and utilities requires 3rd party libraries for
full functionality. (See \ref architecture).
- \ref build_default
- \ref build_classic
- \ref build_hdf4
- \ref build_parallel

\page build_default Building with NetCDF-4 and the Remote Data Client

The usual way of building netCDF requires the HDF5, zlib, and curl
libraries. (And, optionally, the szlib library). 

Get the HDF5 1.8.7 release. You must also have the zlib compression
library, version 1.2.5. Both of these packages are available from the
<a href="ftp://ftp.unidata.ucar.edu/pub/netcdf/netcdf-4">netCDF-4 ftp
site</a>.

Make sure you run ``make check'' for the HDF5 and zlib
distributions. They are very well-behaved distributions, but sometimes
the build doesn't work (perhaps because of something subtly
misconfigured on the target machine). If one of these libraries is not
working, netCDF will have serious problems.

Optionally, you can also build netCDF-4 with the szip 2.0 library
(a.k.a. szlib). NetCDF cannot create szipped data files, but can read
HDF5 data files that have used szip.

There are license restrictions on the use of szip, see
the <a href="http://www.hdfgroup.org/HDF5/">HDF5 web page</a>. These
license restrictions seem to apply to commercial users who are writing
data. (Data readers are not restricted.) But here at NetCDF World
Headquarters, in Sunny Boulder, Colorado, there are no lawyers, only
programmers, so please read the szip documents for the license
agreement to see how it applies to your situation.

If ``make check'' fails for either zlib or HDF5, the problem must be
resolved before the netCDF-4 installation can continue. For HDF5
problems, send email to the HDF5 help desk:
help@hdfgroup.org.

Build zlib like this:

<code>
./configure --prefix=/home/ed/local
make check install
</code>

Then you build HDF5, specifying the location of the zlib library:

<code>
./configure --with-zlib=/home/ed/local --prefix=/home/ed/local 
make check install
</code>

Note that for shared libraries, you may need to add the install
directory to the LD_LIBRARY_PATH environment variable. See
the <a href="http://www.unidata.ucar.edu/software/netcdf/docs/faq.html#Shared%20Libraries">netCDF
FAQ</a> for more details on using shared libraries.

If you are building HDF5 with szip, then include the --with-szlib=
option, with the directory holding the szip library.

After HDF5 is done, build netcdf, specifying the location of the
HDF5, zlib, and (if built into HDF5) the szip header files and
libraries in the CPPFLAGS and LDFLAGS environment variables.

<code>
CPPFLAGS=-I/home/ed/local/include LDFLAGS=-L/home/ed/local/lib ./configure --prefix=/home/ed/local
make check install
</code>

The configure script will try to find necessary tools in your
path. When you run configure you may optionally use the --prefix
argument to change the default installation directory. The above
examples install the zlib, HDF5, and netCDF-4 libraries in
/home/ed/local/lib, the header file in /home/ed/local/include, and the
utilities in /home/ed/local/bin.

\page build_classic Building NetCDF with Classic Library Only

It is possible to build the netCDF C libraries and utilities so that
only the netCDF classic and 64-bit offset formats are support (see
\ref netcdf_format), and the remote data access client is not built
(see \ref remote_client).

<code>
./configure --prefix=/home/ed/local --disable-netcdf-4 --disable-dap
make check install
</code>

(Replace ``/home/ed/local'' with the name of the directory where
netCDF is to be installed.) 

If you get the message that netCDF installed correctly, then you are
done!

\page build_hdf4 Building with HDF4 Support

The netCDF-4 library can (since version 4.1) read HDF4 data files, if
they were created with the SD (Scientific Data) API. To enable this
feature, use the --enable-hdf4 option. The location for the HDF4
header files and library must be set in the CPPFLAGS and LDFLAGS
options.

For HDF4 access to work, the library must be build with netCDF-4
features.

\page build_parallel Building with Parallel I/O Support

For parallel I/O to work, HDF5 must be installed with
–enable-parallel, and an MPI library (and related libraries) must be
made available to the HDF5 configure. This can be accomplished with
the mpicc wrapper script, in the case of MPICH2.

The following works to build HDF5 with parallel I/O on our netCDF
testing system:

<code>
     CC=mpicc ./configure --enable-parallel --prefix=/shecky/local_par --with-zlib=/shecky/local_par && make check install
</code>

If the HDF5 used by netCDF has been built with parallel I/O, then
netCDF will also be built with support for parallel I/O. This allows
parallel I/O access to netCDF-4/HDF5 files (see /ref netcdf_formats).

If parallel I/O access to netCDF classic and 64-bit offset files is
also needed, the parallel-netcdf library should also be installed,
(and the <a
href=ftp://ftp.unidata.ucar.edu/pub/netcdf/contrib/pnetcdf.h>replacement
pnetcdf.h</a> must be used). Then configure netCDF with the
--enable-pnetcdf flag.

\page linking Linking to NetCDF

For static build, to use netCDF-4 you must link to all the libraries,
netCDF, HDF5, zlib, and (if used with HDF5 build) szip. This will mean
-L options to your build for the locations of the libraries, and -l
(lower-case L) for the names of the libraries.

For example, one user reports that she can build other applications
with netCDF-4 by setting the LIBS envoronment variable:

<code>
LIBS='-L/X/netcdf-4.0/lib -lnetcdf -L/X/hdf5-1.8.6/lib -lhdf5_hl -lhdf5 -lz -lm -L/X/szip-2.1/lib -lsz'
</code>

For shared builds, only -lnetcdf is needed. All other libraries will
be found automatically.

The nc-config command can be used to learn what options are needed for
the local netCDF installation.

*/