3 steps to install rvm :
1) gpg --keyserver hkp://keys.gnupg.net --recv-keys D39DC0E3
2) $ \curl -L https://get.rvm.io | bash -s stable
3) source /home/action/.rvm/scripts/rvm
Step 1 installs GPG signatures. rvm has started enforcing GPG signing and the problem surfaced around Oct'31/2014. (https://github.com/wayneeseguin/rvm/issues/3110).
Step 2 installs rvm, while step 3 activates it for use.
Follow it up by checking the rvm version
Nitrous.io users have 2 additional steps to perform after step 1 and these are a result of error messages during the rvm install.
i) unset GEM_HOME
ii) added source ~/.profile to .bash_profile