repl.defineCommand('search', {
    help: 'search through repl history',
    action: function(cmd) {
      if (this.rli.history) this.outputStream.write(this.rli.history.filter(function(line,n) {return n && -1 !== line.indexOf(cmd)}).reverse().join("\n")+"\n");
      this.displayPrompt();
    }
  });