RVM: instsallation

login as user, do the following:

curl -L https://get.rvm.io | sudo bash -s stable
# add user to group rvm
sudo usermod -a -G rvm user
sudo source /etc/profile.d/rvm.sh
# now everyone can use rvm ..

update rvm, install new ruby..

rvm get stable/head
# find local installed ruby version..
rvm automount
rvm list known
rvm install 2.2
# changing to 2.2
rvm use 2.2

if need to specify some version of ruby to be default chosen when opening new terms, rvm use 2.2 --default is the choice.