ncdump and ncgen are inverses:

 

 

1. To edit metadata or data in a netCDF file:

    

   

    

   • Use ncdump to convert netCDF file to CDL
   • Use a text editor to make desired change to CDL
   • Use ncgen to turn modified CDL back into netCDF file
   • Note: not practical for huge netCDF files or if modifying lots of files. For that, need to write a program using netCDF library.
2. To create a new netCDF file with lots of metadata:

    

   

    

   • Use a text editor to write a CDL file with lots of metadata but little or no data.
   • Use ncgen to generate corresponding C or Fortran program for writing netCDF.
   • Insert appropriate netCDF "var_put" calls for writing data.
   • Compile and run program to create netCDF file.
   • Use ncdump to verify result.

2012 Unidata NetCDF Workshop > Utilities for NetCDF-4