Shell script for stripping all Formula-related commits out of a Homebrew repository

update-brew-core

#!/usr/bin/env bash

# Change to repository prefix so that git commands will work.
cd `brew --prefix`

# Ensure Homebrew is up to date and create a new branch called homebrew-core
brew update

git checkout master
git branch -D homebrew-core
git branch homebrew-core

# Create a ramdisk to run filter ops on in order to save the real disks some
# wear and tear.
diskutil erasevolume HFS+ "brew_core_tmp" `hdiutil attach -nomount ram://640000`

git filter-branch -f \
  -d /Volumes/brew_core_tmp \
  --index-filter "git rm -q -r --cached --ignore-unmatch Library/Formula Library/Aliases" \
  --prune-empty homebrew-core

# Dispose of the RAM disk.
umount /Volumes/brew_core_tmp