ncgen

ncgen is a command-line utility in the NetCDF software ecosystem used to convert a CDL (netCDF Description Language) description into source code that can create a NetCDF dataset. The CDL file describes the structure of a dataset, including its dimensions, variables, attributes, and, for NetCDF-4, groups. When ncgen processes the CDL file, it outputs a program in a target language (typically C) that, once compiled and linked with the NetCDF library, will create a NetCDF file that matches the specification in the CDL.

The typical workflow involves writing a CDL file that captures the desired data model and metadata, then invoking ncgen to produce source code. The generated code contains calls to NetCDF library routines to define dimensions, variables, and attributes and to write data where the CDL specifies initial values. Users can redirect the output to a file or to standard output, and then compile the resulting code with an appropriate compiler and linked NetCDF libraries to produce an executable that creates the dataset.

ncgen is part of the NetCDF toolkit and has historically been used to generate example programs or skeleton code for data creation and testing. It complements other NetCDF utilities such as ncdump, which translates NetCDF datasets back into CDL, and the broader NetCDF API libraries that support reading and writing NetCDF data in multiple languages.