WhatInstalls.sh

#!/bin/bash

# Find out what caused the given package to installed,
# i.e. what other package pulled it in as a dependency.

# Usage: ./WhatInstalls.sh package-name

set -e
depending_pkgs_file="$(mktemp)"
installed_pkgs_file="$(mktemp)"

apt-rdepends -r "$1" | grep ':' | cut -d ' ' -f 5 | sort -u > "$depending_pkgs_file"
dpkg --get-selections | cut -f 1 | sort -u > "$installed_pkgs_file"

comm -12 "$depending_pkgs_file" "$installed_pkgs_file"