Automatically migrate amd64 to arm64 brew packages. Removes packages installed under /usr/local and reinstalls (if necessary) under /opt.

xbrew.sh

#!/bin/zsh

confirm=1
while getopts c flag; do
	case "${flag}" in
	c) confirm= ;;
	esac
done

relink() {
	brew unlink $BASE
	brew link $BASE -n | while read -r line; do
		if [[ $line = "Would link:" ]]; then
			continue
		fi

		newPath="/usr/local"
		oldPath="/opt/homebrew"
		OLD_PATH=$(echo "${line/$oldPath/$newPath}")

		if [[ -L "$OLD_PATH" ]]; then
			rm $OLD_PATH
			echo "Remove: $OLD_PATH"
		fi
	done

	mv "/usr/local/Cellar/$BASE" "$HOME/Desktop/CellarBackup/$BASE"
	brew link $BASE

}

for name in /usr/local/Cellar/*/; do
	if [ -d "$name" ] && [ ! -L "$name" ]; then

		oldPath="/usr/local"
		newPath="/opt/homebrew"
		OPT_DIR=$(echo "${name/$oldPath/$newPath}")

		INSTALLED=
		BASE=$(basename "$name")
		if [ -d "$OPT_DIR" ]; then
			INSTALLED=1
			echo "Directory $OPT_DIR exists. $BASE"
		else
			echo "Error: Directory $OPT_DIR does not exists."
		fi

		if [ -z "$INSTALLED" ]; then
			echo "$BASE not installed. Installing..."
			brew install $BASE
		else
			if [ -z "$confirm" ]; then
				read "response?Move old package to backups? [Y/n] "
				response=${response:l} #tolower
				if [[ $response =~ ^(y| ) ]] || [[ -z $response ]]; then
					relink "$BASE"
				fi
			else
				relink "$BASE"
			fi
		fi
	fi
done