script / plugin表示文件存在时找不到命令

Question

我尝试将rails 2.x升级到rails 3.0.0。

我正在遵循本指南（http://www.rails-upgrade-checklist.com/#3.0），它说要下载此rails升级工具：

脚本/插件安装git：//github.com/rails/rails_upgrade.git

当我尝试时，我收到错误：

$ script/plugin install git://github.com/rails/rails_upgrade.git
-bash: script/plugin: Permission denied
$ sudo script/plugin install git://github.com/rails/rails_upgrade.git
Password:
sudo: script/plugin: command not found


$ ls script/
about   dbconsole destroy   performance process   server    spec_server
console   delayed_job generate  plugin    runner    spec    spin
$  

我如何让这个工作起作用，我坚持这么早的一步：）