Ruby 1.9.3-p0 makes psych—the replacement for 1.8.7’s YAML library, Syck—the default YAML parser. Psych is a wrapper around libyaml, so you’re going to need it installed and configured before installing Ruby. If you install 1.9.3-p0 without libyaml, you’ll see warnings like this: It seems your ruby installation is missing psych (for YAML output). To eliminate this warning, please install libyaml a
