安装依赖
yum install zlib-devel curl-devel openssl-devel apr-devel apr-util-devel expat-devel gettext-devel readline-devel gdbm-devel tcl-devel tk-devel
手动安装libyaml否则会提示“yaml.h is missing. Please install libyaml. Failed to configure psych. It will not be installed.”
wget http://pyyaml.org/download/libyaml/yaml-0.1.4.tar.gz
tar zxf yaml-0.1.4.tar.gz
cd yaml-0.1.4
./configure --prefix=你的目录
make
make install
手动安装libffi否则会提示“ffi.h is missing”
wget ftp://sourceware.org/pub/libffi/libffi-3.0.11.tar.gz
tar zxf libffi-3.0.11.tar.gz
cd libffi-3.0.11
./configure --prefix=你的目录
make
make install
ln 安装目录/lib/libffi-3.0.11/include/ffi.h /usr/local/include/ffi.h
安装ruby 1.8（1.9的digest有问题，不知道何故）
wget http://ftp.ruby-lang.org/pub/ruby/1.8/ruby-1.8.7.tar.gz
tar zxf ruby-1.8.7.tar.gz
cd ruby-1.8.7
./configure --prefix=你的目录 --enable-shared --enable-pthread
make
make install
1.9内含rubygem，但1.8要手动安装：
wget http://production.cf.rubygems.org/rubygems/rubygems-1.8.24.tgz
tar zxf rubygems-1.8.24.tgz
cd rubygems-1.8.24
ruby setup.rb
就是这样。搞定。
good