butler.rb

require 'sinatra'
require 'pathname'

get "/" do
  html = "<h1>Your files, sir.</h1>"
  dir = "./files/"
  html += file_link("./files/foo.txt")
  html
end

helpers do
  def file_link(file)
    filename = Pathname.new(file).basename
    "<a href='#{file}'>#{filename}</a><br/>"
  end
end