Homebrew安装主要靠git仓库，切换源实际上就是切换相关git repo的remote url.
具体做法：
- 找到
brew.git和homebrew-core.git的本地repo - 切换两个repo的remote url
切换USTC源：https://lug.ustc.edu.cn/wiki/mirrors/help/brew.git
# 更换brew.git的源
cd "$(brew --repo)"
git remote set-url origin https://mirrors.ustc.edu.cn/brew.git
# 更换homebrew-core.git的源
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-core"
git remote set-url origin https://mirrors.ustc.edu.cn/homebrew-core.git
brew update
另外，还需要更换Homebrew Bottle源，这个只要在shell配置文件里加上（或更改）一个变量即可。
如zsh就是编辑~/.zshrc文件, bash就是~/.bash_profile文件：
export HOMEBREW_BOTTLE_DOMAIN=https://mirrors.ustc.edu.cn/homebrew-bottles
切换清华源：https://mirror.tuna.tsinghua.edu.cn/help/homebrew/
cd "$(brew --repo)"
git remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/brew.git
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-core"
git remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-core.git
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-science"
git remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-science.git
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-python"
git remote set-url origin https://mirrors.tuna.tsinghua.edu.cn/git/homebrew/homebrew-python.git
brew update
重置官方源：
# 重置brew.git:
cd "$(brew --repo)"
git remote set-url origin https://github.com/Homebrew/brew.git
# 重置homebrew-core.git:
cd "$(brew --repo)/Library/Taps/homebrew/homebrew-core"
git remote set-url origin https://github.com/Homebrew/homebrew-core.git
