How to use the child_process.exec.apply function in child_process

}

        if (stdout) {
          console.log(stdout);
        }
      }

      if (err) {
        return reject(err);
      }

      return resolve();
    };

    args.push(cb);
    exec.apply(exec, args);
  }.bind(this));
}

var argv = [].slice.call(arguments),
          _env = JSON.parse(JSON.stringify(process.env));

      if (argv.length === 2) {
        argv = [ argv[0] ].concat({ cwd: dirPath }).concat(argv[1]);
      }
      else {
        argv[1].cwd = argv[1].cwd
          ? path.join(dirPath, argv[1].cwd)
          : dirPath
        ;
      }

      argv[1].env = _env;

      return exec.apply(exec, argv);
    };