Uploading images with Ruby and Sinatra http://www.gideondsouza.com/blog/uploading-images-with-ruby-and-sinatra/

img_mgr.rb

require 'sinatra'

get "/" do
  erb :form
end

post '/save_image' do

  @filename = params[:file][:filename]
  file = params[:file][:tempfile]

  File.open("./public/#{@filename}", 'wb') do |f|
    f.write(file.read)
  end

  erb :show_image
end