Painless is a simple, secure scripting language available in Elasticsearch by default. It was designed by Elasticsearch guys specifically to be used with Elasticsearch and can safely be used with inline and stored scripting. Its syntax is similar to Groovy.
You need an up-and-running Elasticsearch installation as we described in the Downloading and installing Elasticsearch recipe in Chapter 2, Downloading and Setup.
To execute curl via the command line you need to install curl on your operating system.
To be able to use regular expressions in Painless scripting, you need to activate them in your elasticsearch.yml adding the following:
script.painless.regex.enabled: true
To correctly execute the following commands, you need an index populated with the chapter_09/populate_for_scripting.sh script available in the online code.
