Elasticsearch ^6.4.0 on ubuntu code example

Example 1: install elasticsearch ubuntu 18.04

curl -fsSL https://artifacts.elastic.co/GPG-KEY-elasticsearch | sudo apt-key add -

echo "deb https://artifacts.elastic.co/packages/7.x/apt stable main" | sudo tee -a /etc/apt/sources.list.d/elastic-7.x.list