Creating a New Application

We’re going to create a new Rails application named scriba. First we need to create a projects directory. Don’t forget about the Rails Beginner Cheatsheet in case you get stuck.

Install Rails

The first thing we need to do is ensure that the rails gem is installed on the system. Open your terminal and install the gem:

$ gem install rails

There are a lot of dependencies, so this could take a few minutes.

Create Projects

Now we can start setting up the project. Create a projects directory that will contain all of your web application projects.

$ mkdir -p ~/projects

Verify that the projects directory was created by running the list command. You should see the new directory in the output. Once you verify that the directory is there, you can change the directory to projects.

$ ls
$ cd projects

Create New Rails Application

Now we’re ready to create a new Rails application. We do this by running the rails command, giving it a name for the project.

$ rails new scriba

There will be a lot of output as Rails generates the files needed for your application. Once finished, change directories into the new scriba directory.

$ ls
$ cd scriba

Now that we’re here, list what’s in the directories. You should see directories like app and config. This is where all of the files Rails needs to work are located. Before we start working on anything, let’s make sure that the application is working. We can start the included web server with this command:

$ bin/rails server

Open your web browser to http://localhost:3000. You should see something along these lines.

Welcome Abort

When you are ready to stop the server, hit the ctrl and c keys at the same time.

Rails Anatomy

If you run ls in your scriba directory, you’ll notice there are a lot of files and directories because of the convention over configuration principal. Convention over configuration simply means that emphasis is placed on using already established ways of creating code and where those files should be placed, rather than trying to figure those things out from scratch. Some assumptions and ways of doing things are already made for you. The following outlines what the different parts of what each do the in the application.

File/Folder	Purpose
app/	Contains the controllers, models, views, helpers, mailers and assets for your application. You'll focus on this folder for the remainder of this guide.
bin/	Contains the rails script that starts your app and can contain other scripts you use to deploy or run your application.
config/	Configure your application's routes, database, and more. This is covered in more detail in Configuring Rails Applications.
config.ru	Rack configuration for Rack based servers used to start the application.
db/	Contains your current database schema, as well as the database migrations.
Gemfile Gemfile.lock	These files allow you to specify what gem dependencies are needed for your Rails application. These files are used by the Bundler gem. For more information about Bundler, see the Bundler website.
lib/	Extended modules for your application.
log/	Application log files.
public/	The only folder seen by the world as-is. Contains static files and compiled assets.
Rakefile	This file locates and loads tasks that can be run from the command line. The task definitions are defined throughout the components of Rails. Rather than changing Rakefile, you should add your own tasks by adding files to the lib/tasks directory of your application.
README.rdoc	This is a brief instruction manual for your application. You should edit this file to tell others what your application does, how to set it up, and so on.
test/	Unit tests, fixtures, and other test apparatus. These are covered in Testing Rails Applications.
tmp/	Temporary files (like cache, pid, and session files).
vendor/	A place for all third-party code. In a typical Rails application this includes vendored gems.

Git

Now that we have something that is working, it is a good time to get everything we have in git. We first need to initialize the repository, then add the generated files, then commit them with a message about what we did so far.

$ git init
...
$ git add .
$ git commit -m "Generated initial rails application"

Summary

Congratulations! You just created your first Rails application. It doesn’t do much (yet), but is a fully functioning Rails application. In the next module we’ll talk a bit about what the pieces of a Rails application are and how to start making the application do what we need it to.