Install Ruby On Rails

This guide will help you to configure your development environment for real world Rails development. These install instructions are for Ruby on Rails for Mac OS X Yosemite but can be adapted to other operation systems / platforms with minor os / platform specification adjustments. Feel free to leave a comment in case if you're stuck with an issue during the installation.

Command Line Tools

Before you start the installation, you'll need to ensure that Command Line Tools are installed on your Mac. The Xcode Command Line Tools provide a C language compiler needed to install Ruby. For many Rails projects, you will need the C language compiler to install gems that use native extensions. If you don't have the Command Line Tools installed, you can do so using the following command:

xcode-select --install

You can verify the installation using the following command:

xcode-select -p

Ruby Version Manager

While you develop more than one project, you'll install gems and consequently might get into a dependency mess. Also, different projects might be using different version of Ruby. So, we'll need an easy way to switch between Ruby Versions. Ruby Version Manager (RVM) comes to our rescue here. RVM manages Ruby versions and gems and int can be also used to install Ruby.

Homebrew

RVM requires Homebrew which is a package manager for Mac OS X. To avoid RVM installation issues, install Homebrew before RVM. You can install Homebrew using the following command:

ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

After the above command completes, remember to execute the following commands:

brew doctor

brew update

Before any other step install mpapis public key (might need gpg2) 

gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3

Finally, install RVM using:

\curl -sSL https://get.rvm.io | bash -s stable

You can skip stable if you want to install the development version.

Reload your bash_profile, so it can initialise RVM using the following command:

~/.bash_rc

Run the following command to install the required packages:

rvm requirements

To install the latest stable version of Ruby, execute the following command:

\curl -sSL https://get.rvm.io | bash -s stable --ruby

To install the latest version of Rails, execute the following command:

\curl -sSL https://get.rvm.io | bash -s stable --rails

You can install the database of your choice using Homebrew. To install MySQL, execute the following command:
brew install mysql 

To install MongoDB using the following command:
brew install mongo

To install PostgresSQL, execute the following command:

brew install postgresql