brew 更新
zandeMacBook-Pro:~ juluad$ brew update
Error: Failure while executing: git rev-parse -q --verify HEAD brew 安装 mongodb
andeMacBook-Pro:~ juluad$ sudo brew install mongodb
Error: Cowardly refusing to `sudo brew install`
You can use brew with sudo, but only if the brew executable is owned by root.
However, this is both not recommended and completely unsupported so do so at
your own risk.
zandeMacBook-Pro:~ juluad$ brew install mongodb
Error: Cannot write to /usr/local/Cellar求大神指导一下
brew update 一下就好。
看来像权限问题，修复
sudo chown $(whoami) $(brew --prefix)如果更新了 EI Capitan 后出现的问题，请参考：EI Capitan & Homebrew