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[netCDF #MAP-823711]: how to modify the length of the record dimension in an existing netcdf file?

Hi Marc,

> I think that I found a work around to my problem, but I 'd like your opinion 
> to know if what I do is correct. I used the attach script replaceByte.sh to 
> modify directly the byte of the value of the record dimension through the 
> command
> ./replaceByte.sh my_corrupted_file.nc 7 $new_value
> where the variable $new_value is the correct value of the record dimension. 
> By doing so, I am able to work on the netcdf file as usual (ncdump, ncview, 
> matlab, ...) and the data seem to be correct. My only concern, is that I 
> might forget to replace some other bytes but, if my crude understanding of 
> the netcdf storage is correct, there are no other bytes related to the record 
> dimension. What do you think?

If you just updated bytes 4 through 7 of the netCDF file, you did exactly the 
right thing.

That's the only place the number of records is stored in a classic or 
64-bit-offset netCDF
file, as a bigendian 4-byte integer.

--Russ

> Thanks in advance for your time.
> 
> Marc
> 
> PS: I forgot to mention that the format of the file is NetCDF 64-bit offset.
> 
> 
> 
> 
> On 2013-08-06, at 6:32 PM, Unidata netCDF Support wrote:
> 
> >
> > Marc d'Orgeville,
> >
> > Your Ticket has been received, and a Unidata staff member will review it 
> > and reply accordingly. Listed below are details of this new Ticket. Please 
> > make sure the Ticket ID remains in the Subject: line on all correspondence 
> > related to this Ticket.
> >
> >    Ticket ID: MAP-823711
> >    Subject: how to modify the length of the record dimension in an existing 
> > netcdf file?
> >    Department: Support netCDF
> >    Priority: Normal
> >    Status: Open
> >
> >
> >
> > The NetCDF libraries are developed at the Unidata Program Center,
> > in Boulder, Colorado, funded primarily by the National Science Foundation.
> >
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> >
> > It is in the nature of support requests that the same question is asked many
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> >
> > http://www.unidata.ucar.edu/search.jsp?support&netcdf
> >
> > If you are having trouble building netCDF, please take a look at the
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> >
> > http://www.unidata.ucar.edu/software/netcdf/docs/building.html
> >
> > or the (unfortunately somewhat out-of-date) NetCDF Build Troubleshooter 
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> >
> > http://www.unidata.ucar.edu/software/netcdf/docs/troubleshoot.html
> >
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> >
> > http://www.unidata.ucar.edu/software/netcdf/docs/faq.html#windows_netcdf4_2
> >
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> >
> > If you resolve your issue through one of these methods, please send a reply 
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> > Best regards,
> >
> > Unidata User Support
> >
> 
> 
> 

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



Ticket Details
===================
Ticket ID: MAP-823711
Department: Support netCDF
Priority: Normal
Status: Closed