==> Downloading and installing Homebrew...
fatal: cannot copy '/Applications/Xcode.app/Contents/Developer/usr/share/git-core/templates/hooks/fsmonitor-watchman.sample' to '/usr/local/Homebrew/.git/hooks/fsmonitor-watchman.sample': Permission denied
Failed during: git init -q 复制
https://stackoverflow.com/questions/40592463/homebrew-install-fails-while-copying-files
sudo chown -R $(whoami) /usr/local 复制
参考
http://book.51cto.com/art/201012/240858.htm