A multiline grep.

multi_grep.rb

class MultiGrep
  def usage
    puts "Example: ruby multi_grep.rb base.php:10-20 search/*.php"
  end

  def grep(argv = ARGV)
    base = argv.first
    path, range = base.split(":")
    s, e = range.split("-").map { |i| i.to_i }

    File.open(path) do |f|
      base_lines = f.readlines[s-1..e-1].map { |line| line.rstrip }
      base_line = base_lines.first
      array_size = base_lines.size
      argv[1..-1].each do |path|
        File.open(path) do |f|
          lines = f.readlines.map { |line| line.rstrip }
          lines.each_with_index do |line, i|
            if line == base_line && match(lines, base_lines, i, i + array_size - 1)
              puts "#{path}:#{i+1}-#{i+array_size}"
            end
          end
        end
      end
    end
  end

private
  def match(lines, base_lines, start_index, end_index)
    base_lines == lines[start_index..end_index]
  end

end

if __FILE__ == $0
  if ARGV.first =~ /(.+):[\d]+-[\d]+/
    MultiGrep.new.grep
  else
    MultiGrep.new.usage
  end
end