ubuntu12下用rvm安装ruby on rails

在ubuntu下安装最新的ruby on rails，这里使用rvm
1安装rvm

sudo apt-get install curl

curl -L get.rvm.io | bash -s stable

2 读取rvm

source ~/.rvm/scripts/rvm

3 查找环境

rvm requirements

4 安装ruby

 rvm install 1.9.3

5 安装几个库

sudo apt-get install curl bison build-essential git-core 

sudo apt-get install zlib1g-dev libssl-dev libreadline-gplv2-dev lib64readline-gplv2-dev  libxml2-dev

6 安装zlib

rvm pkg install zlib

7 重新安装ruby

rvm remove 1.9.1

rvm install 1.9.1

6,7步是避免安装rails出现如下问题：

liusheng@ubuntu:~$ gem install rails 
ERROR:  Loading command: install (LoadError)
    cannot load such file -- zlib
ERROR:  While executing gem ... (NameError)
    uninitialized constant Gem::Commands::InstallCommand

8 此问题需要设置代理

Could not find a valid gem 'rdiscount' (>= 0) in any repository

应对如下：

$ gem source -r http://rubygems.org/
$ gem source -a http://ruby.taobao.org
gem install bundler rails