Ruby on Rails in OS X Snow Leopard - what versions do I have installed?

I've been trying to get Ruby on Rails working on my Snow Leopard 64-bit MacBook Pro. I followed the instructions in Agile Web Development with Rails and everything seemed to install fine (and allows me to create a demo site), but I got an error to do with sqlite3 when trying to start the web server on my simple demo site (see this question for details of the error I get). I suspect at some point I've managed to install the wrong version or achitecture of a package (I'm using MacPorts) which is causing the problems.

Note: I'm not re-asking that previous question, what I want to know is Is there a way I can determine exactly which versions of each ruby package I have installed, and for what architecture they were built?

I've (foolishly) lost track of the sudo port install lines I've typed so I'm not sure what's currently on my system to try to diagnose how to fix it.

I'd like a list of something like:

Ruby v.1.9.2 - 开发者_StackOverflow64bit
Rails v 2.1 - 32bit
... etc.

Alternatively can I do something (short of reinstalling OS X and XCode) to remove all traces of Ruby from my system and start again?

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If you have advice on how to fix the sqlite3 error I'm getting, please answer on the question linked to above, not here.

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sudo port list installed will show you what ports you have installed

I would look at installing RVM (http://rvm.beginrescueend.com/) as well (as it allows you to keep all the rubies separate). and makes it easy to totally remove a ruby and all its gems/etc..

Did you install ruby from ports or are you using the system ruby?
What does ruby -v or which ruby show ?