On Tue, 3 Dec 2019, Max wrote:
I was trying to create a udev rule to start a zita-a2j ALSA to Jack
bridge automatically if i plug in a specific USB device.
Has anyone succeeded doing something like this?
One issue is that the user is wrong, udev rules are not launched by the
user account.
I chose the other route and listen to the system side of dbus for the
right signal. This does mean there has to be something running to monitor
dbus. The up side is that daemon also knows that jack is actually running
and so only starts zita-ajbridge if there is a jack to work with.
If you are not running dbus then you will need to set your user in the
script udev calls. Then check that jack is running and then you can run
zita-ajbridge and detach it so the udev script can exit.
From experience, you will also need to send the zita-ajbridge a SIGINT
when UDEV detects that device has left. If you do not have anything
sitting around to read the exit info from zita-ajbridge it will leave
zombie processes. While having zombies hanging around is not really a
problem, actually having zita-ajbridge continue to run after the USB
device has vanished tends to use a lot of cpu.
--
Len Ovens
www.ovenwerks.net
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