$ bundle exec rails server -h
Usage: rails server [mongrel, thin, etc] [options]
-p, --port=port Runs Rails on the specified port.
Default: 3000
-b, --binding=ip Binds Rails to the specified ip.
Default: 0.0.0.0
-c, --config=file Use custom rackup configuration file
-d, --daemon Make server run as a Daemon.
-u, --debugger Enable ruby-debugging for the server.
-e, --environment=name Specifies the environment to run this server under (test/development/production).
Default: development
-P, --pid=pid Specifies the PID file.
Default: tmp/pids/server.pid
-h, --help Show this help message.