Javascript 为Node.js安装Express时出错

我刚开始学习node.js v.0.6.2和Mac OSX Lion，并学习了有关安装

express

的教程

问题：在安装node.js和npm之后，我试图通过键入

npm install-g express来安装
express
。但是，我遇到了一系列错误：

npm ERR! error installing express-unstable@2.4.3 Error: Refusing to delete: /usr/local/bin/express not in /usr/local/lib/node_modules/express-unstable
npm ERR! error installing express-unstable@2.4.3     at clobberFail (/usr/local/lib/node_modules/npm/node_modules/rimraf/rimraf.js:110:12)
npm ERR! error installing express-unstable@2.4.3     at next (/usr/local/lib/node_modules/npm/node_modules/rimraf/rimraf.js:97:42)
npm ERR! error installing express-unstable@2.4.3     at /usr/local/lib/node_modules/npm/node_modules/rimraf/rimraf.js:105:12
npm ERR! error installing express-unstable@2.4.3     at Object.cb [as oncomplete] (/usr/local/lib/node_modules/npm/node_modules/graceful-fs/graceful-fs.js:36:9)
npm ERR! error rolling back express-unstable@2.4.3 Error: Refusing to delete: /usr/local/bin/express not in /usr/local/lib/node_modules/express-unstable
npm ERR! error rolling back express-unstable@2.4.3     at clobberFail (/usr/local/lib/node_modules/npm/node_modules/rimraf/rimraf.js:110:12)
npm ERR! error rolling back express-unstable@2.4.3     at next (/usr/local/lib/node_modules/npm/node_modules/rimraf/rimraf.js:97:42)
npm ERR! error rolling back express-unstable@2.4.3     at /usr/local/lib/node_modules/npm/node_modules/rimraf/rimraf.js:105:12
npm ERR! error rolling back express-unstable@2.4.3     at Object.cb [as oncomplete] (/usr/local/lib/node_modules/npm/node_modules/graceful-fs/graceful-fs.js:36:9)
npm ERR! Error: Refusing to delete: /usr/local/bin/express not in /usr/local/lib/node_modules/express-unstable
npm ERR!     at clobberFail (/usr/local/lib/node_modules/npm/node_modules/rimraf/rimraf.js:110:12)
npm ERR!     at next (/usr/local/lib/node_modules/npm/node_modules/rimraf/rimraf.js:97:42)
npm ERR!     at /usr/local/lib/node_modules/npm/node_modules/rimraf/rimraf.js:105:12
npm ERR!     at Object.cb [as oncomplete] (/usr/local/lib/node_modules/npm/node_modules/graceful-fs/graceful-fs.js:36:9)
npm ERR! Report this *entire* log at:
npm ERR!     <http://github.com/isaacs/npm/issues>
npm ERR! or email it to:
npm ERR!     <npm-@googlegroups.com>
npm ERR! 
npm ERR! System Darwin 11.2.0
npm ERR! command "node" "/usr/local/bin/npm" "install" "-g" "express-unstable"
npm ERR! cwd /Users/x/nodejs/chat
npm ERR! node -v v0.6.2
npm ERR! npm -v 1.0.106
npm ERR! path /usr/local/bin/express
npm ERR! code EEXIST
npm ERR! 
npm ERR! Additional logging details can be found in:
npm ERR!     /Users/x/nodejs/chat/npm-debug.log
npm not ok

由于对terminal和git都不熟悉，我不知道发生了什么。有人能告诉我什么时候错了，我怎样才能改正吗？谢谢
 尝试
npm安装-gexpress@2.5.1
删除
/usr/local/bin/express
和
/usr/local/lib/node\u模块/express

再次安装：

npm安装-g express

指定Node.js或npm的版本

您可以使用应用程序package.json的引擎部分指定要在Heroku上使用的Node.js和npm的版本

{

  "name": "myapp",

  "version": "0.0.1",

  "engines": {

    "node": "0.8.x",

    "npm":  "1.1.x"

  }

}

Node.js和npm的可用版本可以通过以下方式找到：


如果未指定版本，将获得以下默认值：

* Node.js: 0.4.7
* npm: 1.0.106

* Node.js: 0.4.7
* npm: 1.0.106