Rails edge bootstrap

#!/usr/local/bin/ruby

# inspired by http://ariejan.net/2009/01/04/how-to-start-a-rails-edge-app-the-easy-way/
require 'fileutils'

def launch(cmd); puts cmd; throw "Error!" unless system(cmd); end
def bye(message); puts message; exit -1; end

bye "Syntax: my_rails app_name" unless (app_name = ARGV.first)
bye "Folder #{app_name} already there! Remove it first." if File.exists?(app_name)

launch "mkdir -p #{app_name}/vendor"

FileUtils.chdir app_name

launch "git clone git://github.com/rails/rails.git vendor/rails"
launch "ruby vendor/rails/railties/bin/rails ."

FileUtils.chdir '..'