how to install brew:
ruby -e "$(curl -fsSL https://raw.github.com/mxcl/homebrew/go)"


after update osx version , error occur:
-bash: /usr/local/bin/brew: /System/Library/Frameworks/Ruby.framework/Versions/1.8/usr/bin/ruby: bad interpreter: No such file or directory
you can do this:
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"