amixer:tldr:b32b2

The command "amixer -D pulse sset Master ${10%+}" is used to control the volume of the PulseAudio sound server using the "amixer" command-line tool.

Here's a breakdown of the command:

• "amixer" is the command-line tool in Linux used to control audio settings.
• "-D pulse" specifies that the target audio device is the "pulse" sound server (PulseAudio).
• "sset" is short for "simple set" and is used to set the value of a control element.
• "Master" is the name of the control element representing the master volume control.
• "${10%+}" is a parameter expansion syntax that takes the value of the 10th argument passed to the command and removes the trailing "+" character, if present.

In summary, this command sets the volume of the PulseAudio master audio control using the value specified as the 10th parameter (presumably passed from another part of the script). The trailing "+" character is removed from the value before setting the volume.