gistfile1.sh

# Install specific version of Homebrew formula
# usage example:
# $ brew-install ssh-copy-id 6.0p1
function brew-install {
  local formula version formula_hash
  formula=$1
  version=$2

  cd `brew --prefix`
  git_last_commit_id=`git rev-parse --short HEAD`

  formula_hash=`brew versions $formula|grep $version|awk '{print $4}'`

  echo brew install $formula with version $version $formula_hash

  git pull
  git checkout $formula_hash Library/Formula/$formula.rb

  brew unlink $formula
  brew install $formula
  brew switch $formula $version
  git checkout $git_last_commit_id Library/Formula/$formula.rb   # reset formula

  cd - # got back to previous dir
}