Make a Sticky Gemset

RVM gives us a convenient technique to make sure we are always using the
correct gemset when we enter the project directory. It will create
hidden files to designate the correct Ruby version and project-specific
gemset. Enter this command to create the hidden files:

$ rvm use ruby-2.1.1@learn-rails --ruby-version

If you see “ERROR: Gemset ‘learn-rails’ does not exist”, perhaps you
overlooked an earlier step in the Project-Specific Gemset section (in
the previous chapter) where we created the learn-rails gemset. No
matter, you can create it now:

$ rvm use ruby-2.1.1@learn-rails --create --ruby-version
$ gem install rails

The --ruby-version argument creates two files, .ruby-version and
.ruby-gemset, that set RVM every time we cd to the project directory.
Without these two hidden files, you’d need to remember to enter rvm use
ruby-2.1.1@learn-rails every time you start work on your project after
closing the console.