To run the server from the terminal without having to write rackup all the time, you can use shotgun, a gem that reloads the application with every request.

You can install it with the gem command:

$ gem install shotgun

To easy its usage, you just need to create a file with the name makefile with the following content:

server:
	shotgun -o 0.0.0.0

It is important to use a <tab> to indent the commands and not spaces.

Then you can run:

$ make server

This is what you get in response:

shotgun -o 0.0.0.0
== Shotgun/WEBrick on http://0.0.0.0:9393/
[2014-08-09 20:40:18] INFO  WEBrick 1.3.1
[2014-08-09 20:40:18] INFO  ruby 2.1.2 (2014-05-08) [x86_64-darwin13.0]
[2014-08-09 20:40:18] INFO  WEBrick::HTTPServer#start: pid=23274 port=9393

Now your application lives in http://localhost:9393 and you no longer have to manually restart your server all the time.

:)