Problem installing ruby on Ubuntu server: "It seems your ruby installation is missing psych (for YAML output). To eliminate this warning, please install libyaml and reinstall your ruby."

I'm getting this issue when I'm trying to install ruby:

It seems your ruby installation is missing psych (for YAML output). To eliminate this warning, please install libyaml and reinstall your ruby.

The solution is to completely remove ruby, then reinstall what is necessary and reinstall it:

rvm uninstall all

sudo apt-get gcc install build-essential openssl libreadline6 libreadline6-dev curl git-core zlib1g zlib1g-dev libssl-dev libyaml-dev libsqlite3-dev sqlite3 libxml2-dev libxslt-dev autoconf libc6-dev ncurses-dev automake libtool bison subversion pkg-config

rvm install 1.9.3

There you have it!