Volume control script for pulseaudio. Here dunstify is being used, since it has some useful options that notify-send doesn't have.

volumectl-pactl.sh

#!/usr/bin/bash

DEFAULT_SINK=$(pactl list sinks | awk '/^Sink/{getline; getline; sub(/^[ \t]+Name: /, ""); print}' | sort | head -n 1)

drawVol(){
    getVol=$(pactl get-sink-volume $DEFAULT_SINK | awk '{print $5}')
    getVolTrim=${getVol::-1}
    dunstify -u low -r 9993 -h int:value:"$getVolTrim" "Volume: ${getVol}" -t 2000
}

drawHelp(){
    echo "Usage: volumectl.sh [OPTION]"
    echo "      -h, --help,                 Help message"
    echo "      -s, --set VOLUME            Set volume"
    echo "      -dec, --decrease            Decrease volume"
    echo "      -inc, --increase,           Increase volume"
    echo "      -rs, --restart              Restart volume (sets it on 100%)"
    echo "      -t, --toggle                Toggle mute"
}

setVol(){
    local vol=$1
    if [ -n "$vol" ] && [ "$vol" -ge 0 ]; then
        pactl set-sink-mute $DEFAULT_SINK no; pactl set-sink-volume $DEFAULT_SINK $vol%; drawVol
    else
        echo "Error: Invalid volume level. It must be a number greater than 0."
        exit 1
    fi
}

case $1 in
    "-h" | "--help") drawHelp ;;
    "-s" | "--set") setVol $2; shift 2 ;;
    "-dec" | "--decrease")           pactl set-sink-mute $DEFAULT_SINK no; pactl set-sink-volume $DEFAULT_SINK -2%; drawVol ;;
    "-inc" | "--increase")           pactl set-sink-mute $DEFAULT_SINK no; pactl set-sink-volume $DEFAULT_SINK +2%; drawVol ;;
    "-rs" | "-res" | "--restart")    pactl set-sink-mute $DEFAULT_SINK no; pactl set-sink-volume $DEFAULT_SINK 100%; drawVol ;;
    "--toggle" | "-t")               pactl set-sink-mute $DEFAULT_SINK toggle; drawVol ;;
    #$1 =~ ^[0-9]+$) pactl set-sink-mute @DEFAULT_SINK@ $1 ;;
    *) pactl get-sink-volume $DEFAULT_SINK; drawVol ;;
esac