cmdParams := [][]string{
        {filepath.Join(dir, path), "npm", "install"},
        {filepath.Join(pdir, n.path), "gulp"},
    }

func Invoke(cmdParams [][]string) error {
    for _, cp := range cmdParams {
        log.Printf("Starting %s in folder %s...", cp[1:], cp[0])
        cmd := exec.Command(cp[1], cp[2:]...)
        cmd.Dir = cp[0]

        stdout, err := cmd.StdoutPipe()
        if err != nil {
            log.Printf("%s cmd.StdoutPipe() error: %vn", cp[1:], err)
            return
        }
        // Start command:
        if err = cmd.Start(); err != nil {
            log.Printf("%s start error: %vn", cp[1:], err)
            return
        }

        // Stream command output:
        scanner := bufio.NewScanner(stdout)
        scanner.Split(bufio.ScanRunes)
        for scanner.Scan() {
            fmt.Print(scanner.Text())
        }
        if scanner.Err() != nil {
            log.Printf("Reading %s stdout error: %vn", cp[1:], err)
            return
        }

        // Get execution success or failure:
        if err = cmd.Wait(); err != nil {
            log.Printf("Error running %s: %vn", cp[1:], err)
            return
        }
        log.Printf("Finished %s", cp[1:])
    }