bin folder in rails

Working in Ruby on Rails, one should have a very clear understanding about the working of [rails s] with which we start our server and the /bin directory created in our project.

Important points

Any command(like rails s) which we run from the terminal is an executable, residing in one of the folder in load path of our system($PATH)
Rails executable gets installed when we install rails gem.
rails in our [rails s] command is a ruby executable.
Ruby executable means, an executable file written in ruby code.
When we run [rails s] an equivalent command [exec ruby bin/rails server] is executed. Which runs ruby executable [rails] file in bin directory of our project.
All the files in /bin directory of a rails project are ruby executable files.
Binstubs are wrapper scripts around executables, whose purpose is to prepare the environment before dispatching the call to the original executable.
In Ruby world, the most common binstubs are the ones that RubyGems generates after installing a gem that contains executables.

# For example - 
# What happens when we run [gem install rspec-core]. Rspec ships with an executable located at [./exe/rspec] inside of t7he gem.
# After the installation, RubyGems will provide us with the following executables-

# 1. <ruby-prefix>/bin/rspec (binstub generated by RubyGems)
# 2. <ruby-prefix>/lib/ruby/gems/1.9.1/gems/rspec-core-XX.YY/exe/rspec (original)

# The generated binstub <ruby-prefix>/bin/rspec is a short Ruby script, presented in a slightly simplified form here:
 
#!/usr/bin/env ruby
require 'rubygems'

# Prepares the $LOAD_PATH by adding to it lib directories of the gem and
# its dependencies:
gem 'rspec-core'

# Loads the original executable
load Gem.bin_path('rspec-core', 'rspec')

By running command rails s, different files in the rails get initialized in the following sequence -
1. Gemfile
2. config/boot.rb
3. config/application.rb
4. config/environments/development.rb
5. config/initializers/*.rb
6. config/environment.rb
7. config.ru