So I finally upgraded (and then downgraded because of Unity) Ubuntu and reinstalled RVM but I'b stuck with rails 3.1 now, which is fine but all my old projects are in rails 3.0 and 3.1 has some incompatibilities. Off the top of my head RAILS_ROOT is now Rails.root (which all my projects use in someway), and I was having some issues with heroku when trying to upload a small rails 3.1 app I made to play around (since the PG gem wasnt in my gemlist I couldnt run migrations, and then installing the pg gem caused more issues).
So how do I install rails 3.0 again? I cant seem to find it in the repositories
And I know with gem sets I can install both right? Well if I do that, how do I create a new rails project? Which version of rails would use rails new new_app?
Ok, I understand what you need to do. I would highly recommend making a new Gemset using RVM, that way you can start from scratch and not worry about those things.
To do that, run this in your command line with RVM installed:
Once this gemset is created, it will be empty, so you can then proceed to install a younger version of rails, like so:
This should install the older version of rails and its dependencies so that you can still edit and work with your older rails project. Check more of RVM's site for more help on switching between gemsets and creating them.
https://rvm.io//gemsets/
I would still recommend to figure out the differences eventually and move to the newer version for Rails, currently 3.2.5 because they are awesome. Here is some material to show you the differences and new features for when you do that later:
http://railscasts.com/episodes/265-rails-3-1-overview
http://railscasts.com/episodes/282-upgrading-to-rails-3-1
http://railscasts.com/episodes/318-upgrading-to-rails-3-2