To install rbenv-each, clone this repository into your rbenv plugins directory. (You'll need a recent version of rbenv that supports plugin bundles.)
git clone https://github.com/rbenv/rbenv-each.git "$(rbenv root)"/plugins/rbenv-each
$ rbenv help each
Verbose mode will print a header for each ruby so you can distinguish the output.
Note: Version aliases (versions that are just symlinks pointing to another rbenv version) are skipped when iterating through the list of rbenv versions.
$ rbenv each bundle install $ rbenv each -v rake test