rbenv not showing the available ruby versions

Are you asking what the output of that command means? I'm looking at the rbenv documentation, and I think it indicates that rbenv only knows of one version of ruby - the version that came installed with your system.

Edit: If that's not the answer you were looking for, can you tell us what you expected to see? Did you have other versions installed on that machine?

Edit 2: If you want to see a list of versions you can install onto your machine, but aren't installed yet, run:

rbenv install --list

Here is more documentation for this command. This will help!

If you have tried both rbenv install --list and ruby-build --definitions and still can't see the latest Ruby versions on the list, then you need to upgrade ruby-build because that is what rbenv uses to "know" the available versions.

For example, assuming you use Mac OS X and installed ruby-build using Homebrew, you can update ruby-build by invoking:

brew upgrade ruby-build

Now, try listing the available versions again, and you should see the latest ones there.

Edit:

The ruby-build wiki lists a couple of ways of updating it, namely the above one using Homebrew and another one where it is installed as a plugin to rbenv:

cd "$(rbenv root)"/plugins/ruby-build && git pull

Rbenv is usually installed with it's companion ruby-build

You can get the versions available to be installed with:

ruby-build --definitions