code: package it.unibz.inf.ontop.cli;
  
  import com.github.rvesse.airline.annotations.Command;
  import com.github.rvesse.airline.annotations.Option;
  import com.github.rvesse.airline.annotations.OptionType;
  import com.github.rvesse.airline.annotations.restrictions.Required;
  
  import org.eclipse.rdf4j.model.Model;
  import org.eclipse.rdf4j.rio.RDFFormat;
  import org.eclipse.rdf4j.rio.Rio;
  import org.eclipse.rdf4j.rio.WriterConfig;
  import org.eclipse.rdf4j.rio.helpers.BasicWriterSettings;
  
  import java.io.*;
  
  @Command(name = "pretty-r2rml",
          description = "prettify R2RML file using Jena")
  public class OntopR2RMLPrettify implements OntopCommand {
  
      @Option(type = OptionType.COMMAND, name = {"-i", "--input"}, title = "input.ttl",
              description = "Input mapping file in the turtle R2RML format (.ttl)")
      @Required
      protected String inputMappingFile;
  
  
      @Option(type = OptionType.COMMAND, name = {"-o", "--output"}, title = "pretty.ttl",
              description = "Output mapping file in the turtle R2RML format (.ttl)")
      @Required
      protected String outputMappingFile;
  
      @Override
      public void run() {
          try {
              Model m = Rio.parse(new FileInputStream(inputMappingFile), "", RDFFormat.TURTLE);
              m.setNamespace("rr", "http://www.w3.org/ns/r2rml#");
  
              WriterConfig settings = new WriterConfig();
              settings.set(BasicWriterSettings.PRETTY_PRINT, true);
              settings.set(BasicWriterSettings.INLINE_BLANK_NODES, true);
              FileOutputStream os = new FileOutputStream(outputMappingFile);
              Rio.write(m, os, RDFFormat.TURTLE, settings);
              os.close();
          } catch (IOException e) {
              e.printStackTrace();
          }
      }
  }
  