[foodstances]

This post hints at it, but you can install all of those Ruby versions on OpenBSD simultaneously. Ruby 1.8 has its binaries named "ruby18", "irb18", etc. and Ruby 1.9 is "ruby19", "irb19", etc. You can create a symlinks from "ruby" to "ruby19" and "irb" to "irb19" to set a system-wide default but any version can be used.

[djur]

That still doesn't cover cases where you want to use multiple 1.9 versions, or if you want to test different patches, or if you want to use the latest version before your OS packages it. It's still the same basic problem as on Ubuntu.

[asdafa]

Yes, and it's nothing new, you can do the same using Debian and then select the most appropriate version of ruby with update-alternatives... RVM and rbenv do something different, they allow you to _run_ different version of ruby for different apps. The fact that you can use them to set the default ruby for your system* is a quite handy side effect.

* And even then, you don't set the default ruby for the entire system, you set it for your own sessions.