bundlewrap/bundles/pppd/files/wait-until-stopped

#!/bin/bash

(
    while true
    do
        ip link show | grep ppp
        if [[ $? -eq 0 ]]
        then
            sleep 1
        else
            exit 0
        fi
    done
) &

% for service in sorted(services):
(
    while true
    do
        if systemctl is-active ${service}
        then
            sleep 1
        else
            exit 0
        fi
    done
) &
% endfor

wait