I’m a little confused by these posts as well. If you executed the script you posted in your original post without any errors, rails should have been installed. Obviously, you either didn’t do that or there were errors.
There are a few things in that script that are not, IMO, optimal. First, I would not install rails with the --pre flag unless you are experienced with Rails and truly intend to test an unreleased version. Second, his/her first action is to install a bunch of modules starting with build-essential, openssl, etc. My only issue is that RVM, like Rails, is constantly being updated/upgraded and this list quickly gets dated. I would install RVM as follows:
Install curl as follows:
sudo apt-get install curl
Then install RVM:
\curl -L https://get.rvm.io | bash -s stable
Once RVM is installed, run:
rvm requirements
it will give you an updated list of modules to install.
I would also run
rvm notes
it will give you other helpful notes on the install.
At this point, as has already been posted above, I strongly recommend www.railstutorial.org. The tutorial assumes you have RVM installed already, but it then walks you through the installation of ruby, rails, git, etc. so I’m not going to go into it. There are two versions of the tutorial online, a 3.2 version and a 4.0 version (the 4.0 version is beta). I agree with Colin, you should choose the version of ruby, rails, and gems that the tutorial uses. This is particularly important with the 3.2 version. If you don’t use the versions of rspec and capybara that the tutorial uses, you will be very frustrated.