pavumeter(1) on Linux
The text e745f9cd1029, as Debian 11 (Bullseye), Debian 10 (Buster), Debian 9 (Stretch) shipped it.
A volume meter for the PulseAudio sound server
Flags it lists
-
--display -
--help -
--help-all -
--help-gtk -
--record -
-h