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This archive contains answers to questions sent to Unidata support through mid-2025. Note that the archive is no longer being updated. We provide the archive for reference; many of the answers presented here remain technically correct, even if somewhat outdated. For the most up-to-date information on the use of NSF Unidata software and data services, please consult the Software Documentation first.

  • Date: Thu, 30 Jul 1998 09:02:25 -0600
Hi Karishma,

> I have some netcdf files which have data in them and were  apparently not
> properly closed. When I examine them using ncdump they report zero data
> points, although the size is a few meg. 
> Is there a way of recovering them ? I have looked up the netcdf web page
> but couldn't find anything obvious.

From the NetCDF User's Guide for C, section 4.1 (Creating a NetCDF
Dataset): 

    Finally, you should explicitly close all netCDF datasets that have
    been opened for writing by calling nc_close. By default, access to
    the file system is buffered by the netCDF library. If a program
    terminates abnormally with netCDF datasets open for writing, your
    most recent modifications may be lost.  This default buffering of
    data is disabled by setting the NC_SHARE flag when opening the
    dataset. But even if this flag is set, changes to attribute values
    or changes made in define mode are not written out until nc_sync or
    nc_close is called.

and the NetCDF User's Guide for FORTRAN contains a similar passage.

So unfortunately your unwritten data was left in the memory buffers that
were never flushed by a close, and there is no way to recover them.
Sorry about that ...

--Russ

_____________________________________________________________________

Russ Rew                                         UCAR Unidata Program
address@hidden                     http://www.unidata.ucar.edu