解决Mac升级到Mojave后出现xcrun: error: invalid active developer path, missing xcrun的问题

今天升级mac到mojave后，终端里升级brew的时候，弹出一行莫名其妙的错误：

xcrun: error: invalid active developer path (/Library/Developer/CommandLineTools), missing xcrun at: /Library/Developer/CommandLineTools/usr/bin/xcrun
Error: Failure while executing; `git remote set-url origin https://github.com/Homebrew/homebrew-cask` exited with 1.

Google后解决方法，重装xcode command line：

xcode-select --install

然后再升级就没问题了