Not able to install some gems after mountain lion upgrade

Question

I just updated my Macbook to Mountain Lion, but now I\'m not able to install some gems, because of the below error about headers. I looked around and it seems to have to do

Answer 1

Be sure to install Xcode's Command-Line Tools.

This hint helped me with this issue:

sudo ln -s /usr/bin/llvm-gcc-4.2 /usr/bin/gcc-4.2