Install Ruby 1.9.3 with libyaml on Ubuntu11.10

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


$ wget http://pyyaml.org/download/libyaml/yaml-0.1.4.tar.gz
$ tar xzvf yaml-0.1.4.tar.gz
$ cd yaml-0.1.4
$ ./configure --prefix=/usr/local
$ make
$ make install


然后再重新安装ruby就可以了