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

I had this problem. libyaml wouldn't compile. It turns out I was missing libtool.

yum install libtool
yum install libyaml (or rvm pkg install libyaml)
rvm reinstall 1.9.3

That solved my problem.