Jim,
> I am in need of a function that can identify a file as netcdf3, netcdf4, or
> pnetcdf 64-bit.
> Preferably I would like this function to work without having linked any of
> the mentioned netcdf libraries.
>
> Does anyone have or know of one?
Although it doesn't match your preference for independence from netCDF
libraries, the nc_inq_format() function documented here:
http://www.unidata.ucar.edu/software/netcdf/docs/netcdf-c.html#nc_005finq-Family
distinguishes among the 4 netCDF format variants:
http://www.unidata.ucar.edu/software/netcdf/docs/faq.html#fv1
in the netCDF-4 library or between classic and 64-bit-offset formats in
a netCDF-3 library. It doesn't recognize the pnetcdf 64-bit variant.
By the way, an HDF5 file can't necessarily be distinguished by its first
4 bytes, because HDF5 files may begin with a "user-block" of size 512,
1024, 2048, ... bytes, before the 4-byte file-type signature.
--Russ
