vagrant@php55:/vagrant/cookbook/mongodb$ sudo gem install berkshelf-api-client -v '1.2.0'
Fetching: multipart-post-2.0.0.gem (100%)
Fetching: faraday-0.9.0.gem (100%)
Fetching: berkshelf-api-client-1.2.0.gem (100%)
Successfully installed multipart-post-2.0.0
Successfully installed faraday-0.9.0
Successfully installed berkshelf-api-client-1.2.0
3 gems installed
Installing ri documentation for multipart-post-2.0.0...
Installing ri documentation for faraday-0.9.0...
Installing ri documentation for berkshelf-api-client-1.2.0...
Installing RDoc documentation for multipart-post-2.0.0...
Installing RDoc documentation for faraday-0.9.0...
Installing RDoc documentation for berkshelf-api-client-1.2.0...
vagrant@php55:/vagrant/cookbook/mongodb$ bundler install
Fetching gem metadata from https://rubygems.org/.......
Fetching additional metadata from https://rubygems.org/..
Using rake 10.2.2
Using addressable 2.3.6
Using ast 1.1.0
Using multipart-post 2.0.0
Using faraday 0.9.0

Gem::InstallError: berkshelf-api-client requires Ruby version >= 1.9.2.
An error occurred while installing berkshelf-api-client (1.2.0), and Bundler cannot continue.
Make sure that `gem install berkshelf-api-client -v '1.2.0'` succeeds before bundling.
vagrant@php55:/vagrant/cookbook/mongodb$ ruby --version
ruby 1.9.3p194 (2012-04-20 revision 35410) [i486-linux]
vagrant@php55:/vagrant/cookbook/mongodb$ berkshelf-api-client
-bash: berkshelf-api-client : commande introuvable
vagrant@php55:/vagrant/cookbook/mongodb$ gem list

*** LOCAL GEMS ***

berkshelf-api-client (1.2.0)
faraday (0.9.0)
multipart-post (2.0.0)