MSGID: <10dei3u$27uve$7@dont-email.me> 9f9c44b5
REPLY:  21d12af7
PID: PyGate 1.5
TID: PyGate/Linux 1.5
CHRS: CP1252 2
TZUTC: 1100
REPLYADDR ldo@nz.invalid
REPLYTO 3:633/10 UUCP
On Thu, 23 Oct 2025 19:09:02 +0100, Adrian wrote:

> If I do a cut and paste of the aplay command, it works fine. So the
> problem looks as though it is some thing to do with the python call.

I would try to confirm this by running the Python script (or at least
a copy of the part that does the aplay command) from a terminal
session. In other words, try to minimize all the differences between
the situation where you can successfully invoke the command, and the
one where you can?t.

> Both command line and python are running under the same user.

I suspect there is some issue with setup of environment variables
(e.g. $HOME) when running the script in the background versus
interactively.

> What I'm seeing logged by the python code is the following error :
>
> ALSA lib pcm_dmix.c:999:(snd_pcm_dmix_open) unable to open slave
> aplay: main:831 audio open error: Unknown error 524
>
> I've tried rebooting again, and an Internet search doesn't come up
> with anything for my particular problem (they all seem to be
> "nothing working").

I did a search for ?alsa Unknown error 524? and found this

where the error was fixed by putting something into the systemwide
ALSA config.

This would be consistent with my suspicion that the per-user setup
for your background versus interactive cases is not exactly the same.

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