1.安装命令
curl -LsSf http://github.com/mxcl/homebrew/tarball/master | sudo tar xvz -C/usr/local --strip 1
2.更新brew：brew update
出现错误提示：/usr/local must be writable!
解决：给电脑用户加权限
//www.greatytc.com/p/36250f81e28b
3.重新update时报错
（1）Error: Could not link:
/usr/local/share/doc/homebrew
Please delete these paths and run `brew update`.
删除rm -r -f /usr/local/share/doc/homebrew
4.检查是否正常：brew doctor
正常：Your system is ready to brew.
