post_install() {
    getent group unbound &>/dev/null || groupadd -r unbound >/dev/null
    getent passwd unbound &>/dev/null || useradd -r -g unbound -G adm -d /etc/unbound -s /bin/nologin -c unbound unbound >/dev/null
    if ! groups unbound | grep adm &>/dev/null; then
        gpasswd -a unbound adm >/dev/null
    fi
    unbound_shell=$(getent passwd unbound | cut -d: -f7)
    if [ "$unbound_shell" != '/bin/nologin' ]; then
        chsh -s /bin/nologin unbound &>/dev/null
    fi
}