In this mini post I’ll show you how to switch to another ruby versions using rbenv. Unlike RVM, rbenv does not offer a command like rvm use but will always respect your project’s .ruby-version file.

You have several options:

1. rbenv shell
2. rbenv local
3. rbenv global

But choose wisely, for while the true command will bring you life, the false command will take it from you.

Temporarily: rbenv shell

Changes your Ruby version on your current shell:

$ ruby -v 
ruby 1.9.3p484 (...)

$ rbenv shell 2.0.0-p353 
$ ruby -v 
ruby 2.0.0p353 (...) 

Background: This actually sets the RBENV_VERSION environment variable in your terminal session.

Per project: rbenv local

Looks like rbenv shell…

$ ruby -v 
ruby 1.9.3p484 (...) 

$ rbenv local 2.0.0-p353 
$ ruby -v 
ruby 2.0.0p353 (...) 

…but actually writes that version to a .ruby-version in your current directory. Use this only when you want to change the Ruby version on a project, not to change it temporarily (as you’d change your project’s file or clutter whatever directory you are currently in with that file).

Globally: rbenv global

This will also change your Ruby version, but only the one you are using whenever no other version is specified, e.g. via a .ruby-version file or RBENV_VERSION variable.

$ ruby -v 
ruby 1.9.3p484 (...) 

$ rbenv global 2.0.0-p353 
$ ruby -v 
ruby 2.0.0p353 (...) 

$ echo "1.9.3p484" > .ruby-version 
$ rbenv global 2.0.0-p353 
$ ruby -v 
ruby 1.9.3p484 (...) 

Note that this is really your global Ruby version, so calling that on one terminal session will affect other terminal sessions as well – unless they are inside a directory tree using .ruby-version, of course.