To install a gem in a global gemset
rvm @global do gem install ...
To use a specific gemset
rvm use ruby-2.1.4@rails4.1
To make a gemset just for the current stable release:
rvm use ruby-2.1.4@rails4.1 --create
```
**Adding a Gemset to an Existing Application**
If you’ve already created an application with the command *rails new myapp*, you can still create a project-specific gemset. Here’s how to create a gemset for an application named “myapp” and create .ruby-version and .ruby-gemset files in the application’s root directory:
```
$ rvm use ruby-2.2.0@myapp --ruby-version --create
```
You’ll need to install Rails and the gems listed in your Gemfile into the new gemset by running:
```
$ gem install rails
$ bundle install
```
http://railsapps.github.io/installrubyonrails-mac.html
List of my must have gems:
+ Seeing Is Believing http://joshcheek.com/seeing_is_believing (http://roidriscoll.github.io/blog/2014/06/21/seeing-is-believing/)
+ Pry
+ RSpec
(check the current version of rails and ruby)