And to switch in between Ruby version,
usually I'll use `/path/to/ruby -S ruby_script_file`.
In bundler, it's simply:
This way, unicorn_rails is executed with system Ruby,bundle exec /usr/bin/ruby -S unicorn_rails
which is versioned 1.8.7, in a bundler's environment.
 Sorry, rvm is not working for my fish shell on Mac OS 10.6