How to Start New Rails App

#What this
This document is for setting up new Rails app with specific ruby and rails version, too complexed process, by using rbenv, ruby version organizing system.

#Understanding
Directory_you_want_to_build_your_app
├── Gemfile
├── vendor
│　　└── bundle
│　　　　├── ...
│　　　　└── ...
└── YourApp
　　├── app
　　├── assets
　　│   ├── ...

Once You Have to Make 'Gemfile' and 'vendor/bundle' Directory.
After Generate 'YourApp' by Those, You can Delete if You Want.
Then, Dig Into 'YourApp' and do 'bundle install' for 'YourApp'.
This process could be complicated for you.

#How to

###Install rbenv

brew install rbenv

###Install some packages for enable rbenv

brew install openssl
brew install readline
brew install libiconv

###Check Versions Available

rbenv versions -l

###Get ruby version want to use ("2.x.x" is version you want to have)

rbenv install 2.x.x

###Change Ruby version to installed version

rbenv global 2.x.x

###Get proper bundler for specific ruby version

rbenv exec gem install bundler

###Also Rails for specific ruby version

rbenv exec gem install rails

###Make Gemfile in the directory you want to put your new rails app in ("4.x.x" is version of rails you need)

cat << EOS > Gemfile
source "http://rubygems.org"
gem "rails", "4.x.x"
EOS

###Install rails to make rails app

bundle install --path vendor/bundle

###Make rails app

bundle exec rails new MyApp --skip-bundle

###Move into rails directory

cd MyApp

###Bundle install in the new app directory

bundle install --path vendor/bundle

#FINISHED!!!

###Now you can do whatever you want

bundle exec rails server

or

bundle exec rails console

and so...

###Have fun!!!