This is an automatic reloading version of the rackup command
that's shipped with Rack. It can be used as an alternative to
the complex reloading logic provided by web frameworks or in
environments that don't support application reloading.  The
shotgun command starts one of Rack's supported servers (e.g.,
mongrel, thin, webrick) and listens for requests but does not
load any part of the actual application. Each time a request is
received, it forks, loads the application in the child process,
processes the request, and exits the child process. The result
is clean, application-wide reloading of all source files and
templates on each request.    gem install shotgun  Starting a
server with a rackup file:   Using Thin and starting on port
6000 instead of 9393 (default):  shotgun --server=thin
--port=6000  Running Sinatra apps:  shotgun hello.rb  See
'shotgun –help' for more advanced usage.   Shotgun: Rack:
Sinatra:  The reloading system in Ian Bicking's webware
framework served as inspiration for the approach taken