brew是mac上的在線包管理軟件，相當於linux apt以及yum包管理工具
1.取消brew的自動更新（https://blog.csdn.net/yf9595/article/details/79843317）
mac上使用brew install /brew cask install安裝軟件總是先updating HomeBrew…
速度很慢，可以在用戶主目錄下的shell配置文件.bash_profile中添加：
export HOMEBREW_NO_AUTO_UPDATE=true
再執行source ~/.bash_profile， 即可取消自動更新brew，
2.下載慢更新brew三個源
https://learnku.com/articles/18908
https://blog.csdn.net/hardhard123/article/details/84193021
https://lug.ustc.edu.cn/wiki/mirrors/help/brew.git(中科大官網配置)
3.brew install 如果沒有取消自動更新，每次都要更新好久，如果這時候意外按下control+z，再次執行brew install會提示Error: Another active Homebrew update process is already in progress.Please wait for it to finish or terminate it to continue.
解決辦法：rm -rf /usr/local/var/homebrew/locks
4.brew 如果不是在root用戶下安裝的，brew install會提示權限不足，類似這樣的提示
Error: An unexpected error occurred during the `brew link` step The formula built, but is not symlinked into /usr/local Permission denied @ dir_s_mkdir - /usr/local/Frameworks Error: Permission denied @ dir_s_mkdir - /usr/local/Frameworks promote:~ admin$ sudo brew install --HEAD libimobiledevice Password: Error: Running Homebrew as root is extremely dangerous and no longer supported. As Homebrew does not drop privileges on installation you would be giving all build scripts full access to your system.
解決辦法：
sudo chown -R $(whoami):admin /usr/local sudo chown -R $(whoami) Homebrew安裝路徑 brew doctor 檢測下是否解決，再次執行brew install即可正常安裝