simple markdown script. It uses Redcarpet for markdown and Rouge for code syntax highlighting.

mark_red_rouge.rb

#! /usr/bin/env ruby

# Author: Tommaso Pavese
#         tommaso@pavese.me
#         www.wonderingmachine.com
#
# Simple script for markdown using:
#
#   Redcarpet: https://github.com/vmg/redcarpet
#   Rouge:     https://github.com/jayferd/rouge
#

require 'redcarpet'
require 'rouge'
#require 'rouge/plugins/redcarpet'

module MarkRedRouge
  WITH_CODE_CSS = false
  CODE_CSS_CLASS = "code_highlight"

  class RougeHtmlRenderer < Redcarpet::Render::HTML
    include Redcarpet::Render::SmartyPants
    #include Rouge::Plugins::Redcarpet
    
    def block_code(code, language)
      lexer = Rouge::Lexer.find_fancy(language, code) || Rouge::Lexers::PlainText

      formatter = Rouge::Formatters::HTML.new(
        css_class: "#{CODE_CSS_CLASS} #{lexer.tag}",
        line_numbers: true)

      formatter.format(lexer.lex(code))
    end
  end



  class Processor
    def initialize(file_name)
      @input_file_name = file_name
      build_files_and_paths

      @parser = build_markdown_parser
    end


    def build_markdown_parser
      options = { no_intra_emphasis: true,
                 fenced_code_blocks: true}
      Redcarpet::Markdown.new(MarkRedRouge::RougeHtmlRenderer, options)
    end


    def parse!
      @input_md = read_input_file
      @output_html = @parser.render(@input_md)
      write_output
    end


    def build_files_and_paths
      @input_file_path = File.expand_path @input_file_name
      
      abort("input file doesn't exist") unless File.exists? @input_file_path
      
      ext  = File.extname @input_file_name
      base = File.basename @input_file_name, ext
      dir  = File.dirname @input_file_path

      @output_file_path = File.join dir, "#{base}.html"
    end


    def read_input_file
      File.read(@input_file_path)
    rescue
      abort("input file can't be read")
    end


    def try_css(file)
      if WITH_CODE_CSS
        css = Rouge::Themes::Github.render(scope: ".#{CODE_CSS_CLASS}")
        file.write "<style>\n"
        file.write css
        file.write "\n</style>"
      end
    end


    def write_output
      File.open(@output_file_path, 'w') do |file|
        try_css file
        file.write @output_html 
      end
    rescue
      puts "error while writing the output"
    end

  end
end


abort("no input file provided") unless ARGV[0]

processor = MarkRedRouge::Processor.new(ARGV[0])
processor.parse!