How to Check whether the data has been loaded into Elastic Search or Not?

Elastic Stack Elasticsearch
1

I have loaded the csv into Logstash and fed into Elastic Search. Now how can I check or see the data, which I have loaded ?

One way is connecting the datasource to Grafana, we can find. Is there any other way to see ?

2 
curl -XGET localhost:9200/_search

Or use Kibana

3

es head or cerebro