bin/rackup in rack-0.3.0 vs bin/rackup in rack-0.4.0

@@ -4,10 +4,12 @@
 require 'optparse'
 
 automatic = false
 server = nil
 env = "development"
+daemonize = false
+pid = nil
 options = {:Port => 9292, :Host => "0.0.0.0", :AccessLog => []}
 
 opts = OptionParser.new("", 24, '  ') { |opts|
   opts.banner = "Usage: rackup [ruby options] [rack options] [rackup config]"
 
@@ -53,10 +55,18 @@
 
   opts.on("-E", "--env ENVIRONMENT", "use ENVIRONMENT for defaults (default: development)") { |e|
     env = e
   }
 
+  opts.on("-D", "--daemonize", "run daemonized in the background") { |d|
+    daemonize = d ? true : false
+  }
+
+  opts.on("-P", "--pid FILE", "file to store PID (default: rack.pid)") { |f|
+    pid = File.expand_path(f)
+  }
+
   opts.separator ""
   opts.separator "Common options:"
 
   opts.on_tail("-h", "--help", "Show this message") do
     puts opts
@@ -91,12 +101,11 @@
   require 'rack'
   require config
   inner_app = Object.const_get(File.basename(config, '.rb').capitalize)
 end
 
-case server
-when nil
+unless server = Rack::Handler.get(server)
   # Guess.
   if ENV.include?("PHP_FCGI_CHILDREN")
     server = Rack::Handler::FastCGI
 
     # We already speak FastCGI
@@ -109,30 +118,19 @@
       server = Rack::Handler::Mongrel
     rescue LoadError => e
       server = Rack::Handler::WEBrick
     end
   end
-when "mongrel"
-  server = Rack::Handler::Mongrel
-when "webrick"
-  server = Rack::Handler::WEBrick
-when "cgi"
-  server = Rack::Handler::CGI
-when "fastcgi"
-  server = Rack::Handler::FastCGI
-else
-  server = Rack::Handler.const_get(server.capitalize)
 end
 
 p server  if $DEBUG
 
 case env
 when "development"
   app = Rack::Builder.new {
     use Rack::CommonLogger, STDERR  unless server.name =~ /CGI/
     use Rack::ShowExceptions
-    use Rack::Reloader
     use Rack::Lint
     run inner_app
   }.to_app
 
 when "deployment"
@@ -147,8 +145,28 @@
 end
 
 if $DEBUG
   pp app
   pp inner_app
+end
+
+if daemonize
+  if RUBY_VERSION < "1.9"
+    exit if fork
+    Process.setsid
+    exit if fork
+    Dir.chdir "/"
+    File.umask 0000
+    STDIN.reopen "/dev/null"
+    STDOUT.reopen "/dev/null", "a"
+    STDERR.reopen "/dev/null", "a"
+  else
+    Process.daemon
+  end
+
+  if pid
+    File.open(pid, 'w'){ |f| f.write("#{Process.pid}") }
+    at_exit { File.delete(pid) if File.exist?(pid) }
+  end
 end
 
 server.run app, options