  fastPut(localPath, remotePath, opts, cb) {
    if (this.server)
      throw new Error('Client-only method called in server mode');

    fastXfer(fs, this, localPath, remotePath, opts, cb);
  }
The software constructs all or part of an OS command using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the intended OS command when it is sent to a downstream component.