安装Homebrew成功，执行brew update遇到如下问题，怎么解决呢？

Question

Installation successful!
You should run `brew doctor' before you install anything.
Now type: brew help
brew doctor
Warning: A newer Command Line Tools release is available
brew update
fatal: unable to access 'https://github.com/Homebrew/homebrew/': Could not resolve host: github.com
Error: Failure while executing: git pull -q origin refs/heads/master:refs/remotes/origin/master
求帮助，先谢过大家啦

Answer 1

1. 先确定是否能访问 github.com, 如果不能访问，尝试开VPN。
2. terminal 下运行下面的试试：
   cd /usr/local
   git reset --hard
   git checkout .
   brew update