How to install ruby ​​via RVM?

Question

ruby

Hello, before writing here, I pretty much googled, but I did not find anything clear.
OS Ubuntu 14.04 LST x64
Initially, the task was to start using sass , as it turned out, you need to install ruby.
I must say right away that I am not familiar with Ruby, as well as with the features of advanced work in the terminal and batch installers.
After reading about each of the installation methods, I decided to use RVM.
As it turned out, everything was more complicated than it seemed, the rush and unstable Internet connection took their toll. As a result, I threw everything into the terminal that was possible and not possible from the documentation, then the rage divides all folders and files, lines in bash with rvm, sass and everything that was advised on stackoverflow. Then there were more futile attempts.
Now I have:

rvm -v
rvm 1.25.30 (master) by Wayne E.

whereis rvm
rvm:

Tried to install:

rvm install 2.1.1
Searching for binary rubies, this might take some time.
No binary rubies available for: ubuntu/14.04/x86_64/ruby-2.1.1.
Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies.
Checking requirements for ubuntu.
Requirements installation successful.
Installing Ruby from source to: /home/thohoh/.rvm/rubies/ruby-2.1.1, this may take a while depending on your cpu(s)...
ruby-2.1.1 - #downloading ruby-2.1.1, this may take a while depending on your connection...
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100 11.4M  100 11.4M    0     0  7166k      0  0:00:01  0:00:01 --:--:-- 7166k
ruby-2.1.1 - #extracting ruby-2.1.1 to /home/thohoh/.rvm/src/ruby-2.1.1....
ruby-2.1.1 - #applying patch /home/thohoh/.rvm/patches/ruby/2.1.1/libyaml.patch.
ruby-2.1.1 - #applying patch /home/thohoh/.rvm/patches/ruby/changeset_r45225.diff.
ruby-2.1.1 - #applying patch /home/thohoh/.rvm/patches/ruby/changeset_r45240.diff.
ruby-2.1.1 - #configuring....................................................
ruby-2.1.1 - #post-configuration..
ruby-2.1.1 - #compiling.....................................................................................
ruby-2.1.1 - #installing.................................
ruby-2.1.1 - #making binaries executable..
Rubygems 2.2.2 already available in installed ruby, skipping installation, use --force to reinstall.
ruby-2.1.1 - #gemset created /home/thohoh/.rvm/gems/[email protected]
ruby-2.1.1 - #importing gemset /home/thohoh/.rvm/gemsets/global.gems..........................................................
ruby-2.1.1 - #generating global wrappers........
ruby-2.1.1 - #gemset created /home/thohoh/.rvm/gems/ruby-2.1.1
ruby-2.1.1 - #importing gemsetfile /home/thohoh/.rvm/gemsets/default.gems evaluated to empty gem list
ruby-2.1.1 - #generating default wrappers........
ruby-2.1.1 - #adjusting #shebangs for (gem irb erb ri rdoc testrb rake).
Install of ruby-2.1.1 - #complete 
Please be aware that you just installed a ruby that requires 3 patches just to be compiled on an up to date linux system.
This may have known and unaccounted for security vulnerabilities.
Please consider upgrading to ruby-2.1.2 which will have all of the latest security patches.
Ruby was built without documentation, to build it run: rvm docs generate-ri
[email protected]:~$ rvm upgrade 2.1.1 2.1.2
Are you sure you wish to upgrade from ruby-2.1.1 to ruby-2.1.2? (Y/n): y
Migrating gems from ruby-2.1.1 to ruby-2.1.2
Free disk space 148144MB, required 1MB.
Are you sure you wish to MOVE gems from ruby-2.1.1 to ruby-2.1.2?
This will overwrite existing gems in ruby-2.1.2 and remove them from ruby-2.1.1 (Y/n): y
Moving [email protected] to [email protected]..............................................................................................................................
Making gemset [email protected] pristine...............................................................
Moving ruby-2.1.1 to ruby-2.1.2..........................................................................................................
Making gemset ruby-2.1.2 pristine.............................................................
Do you also wish to completely remove ruby-2.1.1 (inc. archive)? (Y/n): y
Removing ruby-2.1.1................
Successfully migrated ruby-2.1.1 to ruby-2.1.2
Upgrade complete!

ruby -v
The program 'ruby' can be found in the following packages:
 * ruby
 * ruby1.8
Try: sudo apt-get install <selected package>

whereis ruby
ruby:

well, nothing is clear with Sass at all:

sass -v
The program 'sass' is currently not installed. You can install it by typing:
sudo apt-get install ruby-sass

gem install sass
<internal:gem_prelude>:1:in `require': cannot load such file -- rubygems.rb (LoadError)
  from <internal:gem_prelude>:1:in `<compiled>'

I know it's noob. Please don’t throw tomatoes at me, just tell me the way how you can return everything to the original one, remove the extra garbage that I most likely made in the system and do everything right from scratch, Graz.
UPD: figured it out, the problem was in the following https://rvm.io/integration/gnome-terminal

Answer 1

rvm --default use 2.1.2