Converts JSON to YAML. Works either with filenames passed in as arguments, or by piping standard input.

json2yaml.rb

require 'json'
require 'yaml'

json_file, yaml_file = ARGV

json_text = nil

unless json_file.nil?
  if File.exist?(json_file)
    json_text = File.new(json_file, 'r').read
  else
    puts "File #{json_file} does not exist!"
    exit
  end
else
  json_text = $stdin.read
end

data = JSON.parse(json_text)

yaml_text = data.to_yaml

unless yaml_file.nil?
  f = File.new(yaml_file, 'w+')
  f.write(yaml_text)
  f.close
else
  $stdout.puts yaml_text
end