check the syntax in a tree of files.rb

lines = `find . -name '*.rb'`.split("\n")

problems = []
lines.each_slice(100) do |slice|
  threads = []
  slice.each do |l|
    threads << Thread.new do
      result = `ruby -c #{l}`
      if "Syntax OK" == result.strip
        print "."
      else
        print "!"
        problems << l
      end
    end
  end
  threads.each{|t| t.join }
end
puts "problems:\n#{problems}" unless 0 == problems.size