MSGID: <10dfs4k$2j983$1@dont-email.me> f67fb7e5
REPLY:  9f478b0c
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REPLYADDR chris@internal.net
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On 24/10/2025 at 13:18, Adrian wrote:
> In message <10dei3u$27uve$7@dont-email.me>, Lawrence 
> =?iso-8859-13?q?D=FFOliveiro?=  writes
>> 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.
>>
> 
> Thanks for the detailed reply.
> 
> I've just tried that, and running the Python interactively works (I get 
> sound). So far, so good.
> 
> In the normal way of things, the Python code is started by cron using 
> @reboot.  Being aware that the environment that cron gets can be 
> different to that of an interactive session, I've just killed off the 
> background Python code, and restarted it using nohup (which I think 
> should give the same environment as the command line).  That still fails 
> (code runs, no sound), but now the error message doesn't appear, instead 
> in the error file, I get the message :
> 
> nohup: ignoring input and appending output to 'nohup.out'
> 
> which it doesn't, that file remains empty.
> 
> So it looks as though the problem is with the Python code running in the 
> background, rather than the Python code itself.  I'm wondering if one of 
> the updates that has run since the previous reboot (~8 weeks ago) has 
> come into play because of yesterday's reboot.
> 
> I forgot to mention that the path to the sound file is absolute, rather 
> than $HOME/...
> 
> When I run Python from the command line, it tells me that I'm running 
> Python 3.11.2
> 
> 
>>> 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.
> 
> I would agree, but see above.  And why did it work pre-reboot ?
> 
>>
>>> 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
>> > open-audio-device-unknown-error-524-what-is-going>
>> 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.
> 
> Thanks.  I tried adding those entries, but it makes no difference.
> 
> And to repeat, the background and foreground sessions are run by the 
> same user, so I think the problem is "how it is being run" rather than 
> "who is running it".
> 
> Adrian

Check your XDG_RUNTIME_DIR and/or PULSE_COOKIE settings. I had to set 
theses to get vlc to play properly from a task set from a non-terminal 
run file though a bluetooth speaker.
HIH


-- 
Chris Elvidge, England
I WILL NOT INSTIGATE REVOLUTION
Bart Simpson on chalkboard in episode 7G06


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