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

for ubuntu and rvm

sudo apt-get install libtool
rvm pkg install libyaml
rvm reinstall 1.9.3

worked