Calling a jruby script from a ruby script (via shell)

1_parent.rb

$jruby_bin       = '/path/to/jruby/bin/jruby'
$children_script = File.join File.expand_path('.'), 'children.rb'

def call_children command = ''
  full_command = "#{$jruby_bin} -r#{$children_script} -e '#{command}'"
  puts "Executing command: #{full_command}"
  system full_command
end

puts "Hello from parent!"
call_children "say_hello"

3_children.rb

require 'java'

def say_hello
  java.lang.System.out.println "Hello from children!"
end

4_result

Running "$ ruby parent.rb", will display:

Hello from parent!
Executing command: /path/to/jruby -r/path/to/children.rb -e 'say_hello'
Hello from children!