how to solve “ruby installation is missing psych” error?

Question

I used rvm to install ruby 1.9.3. even though it was successfully installed, it complained about libyaml. and now every time i wanna install a gem (say rails) this warning s

Answer 1

This worked for me at least on Ubuntu 10.04

$ sudo apt-get install libtool

$ rvm reinstall 1.9.3