Set maximum volume on a Linux computer

#!/bin/bash
maxVol=45
maxSec=90
interval=1

while true; do
  sleep $interval
  curV=$(amixer -c 0 sget Master | grep -Po "(\d\d)%" | grep -Po "\d*")
  pcmV=$(amixer -c 0 sget  PCM | grep -Po "(\d\d)%" | grep -Po "\d*")
  spkV=$(amixer -c 0 sget Speaker | grep -Po "(\d\d)%" | grep -Po "\d*")
  if [ $curV ]; then
    if [ $curV -gt $maxVol ]; then
      resetV=$(amixer -c 0 sset Master $maxVol%)
    fi
    if [ $curV -gt $maxSec ]; then
      resetV=$(amixer -c 0 sset PCM $maxSec%)
    fi
    if [ $spkV -gt $maxSec ]; then
      resetV=$(amixer -c 0 sset Speaker $maxSec%)
    fi
  fi


done &