`gem_original_require': no such file to load -- zlib (LoadError)(转发)

I wanted to install redmine on a centos 5.3.
As ruby 1.6/1.7 packages are not availables on this distribution, i had to download and compile the ruby 1.7 sources.

I installed rubygems sources

This error happened when i tried to make a

gem install rails

To solve it i had to do a

yum install zlib-devel 

then in /opt/ruby/ext/zlib/（即源码目录的ext/zlib下 ）

  ruby extconf.rb
make && make install 

everything is good now!!!