A script to show you outdated brew formulae, but only if they're leaves

brew-outdated-leaves.sh

#!/usr/bin/env bash

# A script to show you outdated brew formulae, but only if they're leaves. 
# Who wants to scan through intermediate libs?

set -euo pipefail
# set -x # echo commands to terminal; for debugging

# with comm - slower for me, but may work better for you?
# FORMULAE=$(comm -12 <(brew outdated --quiet | sort) <(brew leaves))

FORMULAE=$(echo "$(brew outdated --quiet)" "$(brew leaves)" | sort | uniq -d)

brew outdated --verbose $FORMULAE