app.rb

#!/usr/bin/env ruby

require 'rubygems'
require 'sinatra'

set :bind, '0.0.0.0'
set :port, 80

get '/' do
  sensor = '28-000005314719'
  file_contents = `cat /sys/bus/w1/devices/#{sensor}/w1_slave`
  sensor_reading =  file_contents.split("=").last.to_f / 1000
  "The temperature is #{sensor_reading} C."
end

get '/camera' do
  `raspistill -w 640 -h 480 -t 50 -o ./public/image.jpg`
  "<img src='/image.jpg' />"
end