post_install() {
    if ! getent group lxdm > /dev/null ; then
        groupadd --system lxdm
        chgrp -R lxdm /var/lib/lxdm
        chgrp lxdm /etc/lxdm/lxdm.conf
        chmod +r /etc/lxdm/lxdm.conf
    fi
}

post_upgrade() {
    post_install $1
}

post_remove() {
    if ! getent group lxdm > /dev/null ; then
        groupdel lxdm
    fi
}