How to run Elasticsearch 2.1.1 as root user in Linux machine

Based of the following code-snippet looks like you should be able to achieve this by enabling property es.insecure.allow.root

Example :

bin/elasticsearch -Des.insecure.allow.root=true

1. Open script file:

   vi bin/elasticsearch

2. Add property for allow root:

   ES_JAVA_OPTS="-Des.insecure.allow.root=true"

3. Save and close.
4. You can start by root now.

Good luck.