code: function rdf(argv, callback) {
    var command = argv[2];
    var exec;
  
    if (!command) {
      console.log('rdf help for command list');
      process.exit(-1);
    }
  
    try {
      exec = require('./bin/' + command + '.js');
    } catch (err) {
      console.error(command + ': command not found');
      process.exit(-1);
    }
  
    argv.splice(2, 1);
  
    exec(argv, callback);
  
  }
docs: rdf calls child script
  
  @param {string} argv[2] command
  @callback {bin~cb} callback