rails -v returns 2.3.5 but gem uninstall rails offers to uninstall version 3.1

I am trying upgrade Rails. I am pretty sure that Rails 3.1 is now installed, however my rails apps still have no Gemfile, and rails -v returns 2.3.5. When I type "gem uninstall rails" I 开发者_开发知识库get:

aheine@ubuntu:~/www$ gem uninstall rails

Select gem to uninstall:
 1. rails-3.0.9
 2. rails-3.1.0.rc1
 3. rails-3.1.0.rc5
 4. All versions

How can I get rid of Rails 2, and make rails 3 the default version to use?

I am using Ubuntu 11.04

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Your running with the system provided Rails, run apt-get remove rails and then you may need to make a configuration change so the system can find the proper rails command. So see if that works and then try running rails -v if that returns command not found add this line to the beginning of your .bashrc file in your home directory.

export PATH=/var/lib/gems/1.8/bin:$PATH

After that's done open a new shell and try running rails -v again.