I am positive amixer -c $1 scontrols does what I intend (which is to dump that card's enumerated simple controls).
At this point, I am unlikely to find any alsa-utils tool as the culprit, particularly since the entire sequence works without delay (i.e., as expected/normally) on many machines /and/ does not manifest the reported symptom when invoked during an interactive session /not/ associated with shutdown/rebooting. The chronological proximity of the reported symptom to network-related teardown does not seem coincidental.
I am positive amixer -c $1 scontrols does what I intend (which is to dump that card's enumerated simple controls).
At this point, I am unlikely to find any alsa-utils tool as the culprit, particularly since the entire sequence works without delay (i.e., as expected/normally) on many machines /and/ does not manifest the reported symptom when invoked during an interactive session /not/ associated with shutdown/rebooting. The chronological proximity of the reported symptom to network-related teardown does not seem coincidental.