upgrade brews a-la 'apt-get dist-upgrade'

upgradebrews

#!/bin/bash
#
# Very simple script that updates your brew formula repo and
# then upgrades all installed and outdated formulae
# Run with -y to upgrade formulae automatically
#

# Update the repo
brew update

# List of outdated formulae
outdated=$(brew outdated | awk '{print $1}')

# Function that actually upgrades the packages
function upgradebrews() {
	for i in $(brew outdated | awk '{print $1}'); do
		echo "installing $i"
		brew install $i || exit 1
	done
}

# Update any out of date ones
if [ -z "$outdated" ]; then
	echo "All installed formulae are up to date, nothing to do!"
	exit 0
else
	echo "About to upgrade the following formulae: $outdated"
	if [ "$1" != "-y" ]; then
		echo -n 'Proceed with upgrade? (y/n): '
		read proceed
		if [ "$proceed" == "y" ]; then
			echo "Upgrading..."
			upgradebrews
		else
			echo "Aborting..."
			exit 0
		fi
	else
		upgradebrews
	fi
fi

exit 0