#!/bin/sh
[ -z "$(command -v pacman)" ] && echo "You need pacman to run this script." && exit 1

## Retrieve official packages list.
OFFICIAL="$(mktemp)"
FOREIGN="$(mktemp)"
pacman -Qq | sort > "$OFFICIAL"
pacman -Qmq | sort > "$FOREIGN"
comm -3 "$OFFICIAL" "$FOREIGN"
rm -f  "$OFFICIAL" "$FOREIGN"

## Zsh version.
# comm -3 <(pacman -Qq | sort) <(pacman -Qmq | sort)

# Alternative 'diff' verision.
# diff <(pacman -Qq | sort) <(pacman -Qmq | sort) --new-line-format='' --unchanged-group-format='%>'