rails s error

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[vagrant@localhost first_app]$ rails server /home/vagrant/rails_tutorial/first_app/vendor/bundle/ruby/2.0.0/gems/execjs-2.2.2/lib/execjs/runtimes.rb:51:in autodetect': Could not find a JavaScript runtime. See https://github.com/sstephenson/execjs for a list of available runtimes. (ExecJS::RuntimeUnavailable) from /home/vagrant/rails_tutorial/first_app/vendor/bundle/ruby/2.0.0/gems/execjs-2.2.2/lib/execjs.rb:5:inmodule:ExecJS' from /home/vagrant/rails_tutorial/first_app/vendor/bundle/ruby/2.0.0/gems/execjs-2.2.2/lib/execjs.rb:4:in <top (required)>' from /home/vagrant/rails_tutorial/first_app/vendor/bundle/ruby/2.0.0/gems/uglifier-2.1.1/lib/uglifier.rb:3:inrequire' from /home/vagrant/rails_tutorial/first_app/vendor/bundle/ruby/2.0.0/gems/uglifier-2.1.1/lib/uglifier.rb:3:in <top (required)>' from /home/vagrant/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/bundler-1.7.4/lib/bundler/runtime.rb:76:inrequire' from /home/vagrant/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/bundler-1.7.4/lib/bundler/runtime.rb:76:in block (2 levels) in require' from /home/vagrant/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/bundler-1.7.4/lib/bundler/runtime.rb:72:ineach' from /home/vagrant/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/bundler-1.7.4/lib/bundler/runtime.rb:72:in block in require' from /home/vagrant/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/bundler-1.7.4/lib/bundler/runtime.rb:61:ineach' from /home/vagrant/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/bundler-1.7.4/lib/bundler/runtime.rb:61:in require' from /home/vagrant/.rbenv/versions/2.0.0-p353/lib/ruby/gems/2.0.0/gems/bundler-1.7.4/lib/bundler.rb:133:inrequire' from /home/vagrant/rails_tutorial/first_app/config/application.rb:7:in <top (required)>' from /home/vagrant/rails_tutorial/first_app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.5/lib/rails/commands.rb:74:inrequire' from /home/vagrant/rails_tutorial/first_app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.5/lib/rails/commands.rb:74:in block in <top (required)>' from /home/vagrant/rails_tutorial/first_app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.5/lib/rails/commands.rb:71:intap' from /home/vagrant/rails_tutorial/first_app/vendor/bundle/ruby/2.0.0/gems/railties-4.0.5/lib/rails/commands.rb:71:in <top (required)>' from bin/rails:4:inrequire' from bin/rails:4:in `

' [vagrant@localhost first_app]$

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vagrant環境の場合、Gemfileをviエディタで開き #therubyrace・・・・ みたいな部分を　#を消し保存しbunndle installするとrails sでいけると思います。