def set_exe(self, pipes_code):
        """
        Dump launcher code to the distributed file system.
        """
        if not self.output:
            raise RuntimeError("no output directory, can't create launcher")
        parent = hdfs.path.dirname(hdfs.path.abspath(self.output.rstrip("/")))
        self.exe = hdfs.path.join(parent, utils.make_random_str())
        hdfs.dump(pipes_code, self.exe)