Elastic search version

Fetch the elastic search version using

$ curl 'http://localhost:9200/?pretty'
{
  "status" : 200,
  "name" : "Midnight Sun",
  "cluster_name" : "elasticsearch",
  "version" : {
    "number" : "1.6.2",
    "build_hash" : "622039121e53e5f520b5ff8720fdbd3d0cb5326b",
    "build_timestamp" : "2015-07-29T09:24:47Z",
    "build_snapshot" : false,
    "lucene_version" : "4.10.4"
  },
  "tagline" : "You Know, for Search"
}

The elastic search version is 1.6.2

After upgrading to 5.x version of elastic search

$ curl -XGET 'http://localhost:9200'
{
  "name" : "3bsjSYM",
  "cluster_name" : "elasticsearch",
  "cluster_uuid" : "zGjQ_4rBS1aoM-VzJ_hZCA",
  "version" : {
    "number" : "5.2.0",
    "build_hash" : "24e05b9",
    "build_date" : "2017-01-24T19:52:35.800Z",
    "build_snapshot" : false,
    "lucene_version" : "6.4.0"
  },
  "tagline" : "You Know, for Search"
}

The new elastic search version 5.2.0