Go to <JRUBY_HOME>/samples directory.
Create a Rails application called hello:
jruby -S rails hello
This command creates the hello directory, which contains a set of automatically-generated files and directories. The directories containing the files that you'll use the most are:
app: Contains your application code.
config: Contains configuration files, such as database.yml, which you use to configure a database.
public: Contains files and resources that need to be accessed directly rather than accessed through the Rails call stack. These include images and straight HTML files.