@david_chisnall There’s a similar issue with some tests for pf. They use a “server” to send network traffic through pf to, and that server is netcat or inetd, spawned from the test shell script with &. Has the process really started? Even if it has, then did it reach the stage where it can accept a connection? There is no way of telling, so the tests are full of `sleep 1` which if you run a lot of them in parallel is not enough and the tests fail. Systemd has sd_notify.