https://github.com/Homebrew/homebrew/blob/master/share/doc/homebrew/El_Capitan_and_Homebrew.md#el-capitan--homebrew https://github.com/Homebrew/homebrew/blob/ma

https://github.com/Homebrew/homebrew/blob/master/share/doc/homebrew/El_Capitan_and_Homebrew.md#el-capitan--homebrew https://github.com/Homebrew/homebrew/blob/master/share/doc/h... "Apple documentation hints that /usr/local will be returned to root:wheel restricted permissions on every OS X update; Homebrew will be adding a brew doctor check to warn you when this happens in the near future."