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If you haven't changed anything in the config file (/etc/elasticsearch/elasticsearch.yml), you most likely don't have Elasticsearch running. I don't know the exact details of your environment, but you should be able to start it by navigating to the bin directory inside the elasticsearch install directory, and running "./elasticsearch". You can also try "sudo service elasticsearch restart". I found this article very helpful to get everything running on Ubuntu.
I got error when using curl -XGET 'localhost:9200'
couldn't connect to host
I am new to logstash and elasticsearch.
I follow this link to set it up but not 100% working.