如何安装mongodb请参考前一篇文章《mongodb在Linux下的安装》
mongod服务启动之后，我们该启动客户端，./bin/mongo
这个时候其实已经启动成功了，但是会出现一些警告性的错误：
MongoDB shell version: 3.0.6
connecting to: test
Server has startup warnings:
2015-08-28T15:29:38.513+0800 I CONTROL [initandlisten] ** WARNING: You are running this process as the root user, which is not recom...
