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<h1>HDF5 Library Environment Variables and Configuration Parameters</h1>
<h2>1. Environment Variables</h2>
The HDF5 library uses UNIX environment variables to control
or adjust certain library features at runtime. The variables and
their defined effects are as follows:
<dir>
<dl>
<dt><tt>HDF5_DEBUG</tt>
<dd>Defines a list of debugging switches documented in the
<a href="Debugging.html">Debugging</a> section of the
<cite>HDF5 User's Guide</cite>.
<dt><tt>HDF5_NOCLEANUP</tt>
<dd>When set to a non-empty value, the programs in the test
directory do not remove temporary HDF5 data files.
The default is for each test to remove the files before exit.
<dt><tt>HDF5_MPI_OPT_TYPES</tt>
(for parallel beta version only)
<dd>When set to <code>1</code>, PHDF5 will use the MPI optimized
code to perform parallel read/write accesses to datasets.
Currently, this optimization fails when accessing extendable
datasets. The default is not to use the optimized code.
<dt><tt>HDF5_MPI_1_METAWRITE</tt>
(for parallel beta version only)
<dd>When set to <code>1</code>, PHDF5 will write the metadata
via process 0 of each opened parallel HDF5 file. This should
improve I/O throughput. The default is not to use this
optimization.
</dl>
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<h2>2. Configuration Parameters</h2>
The HDF5 configuration script accepts a list of parameters to control
configuration features when creating the Makefiles for the library.
The command
<br>
<code> configure --help </code>
<br>
will display the current list of parameters and their effects.
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Last modified: 14 October 1999
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