Disk space alert for user quota

#!/bin/bash
CURRENT=$(/usr/bin/quota | awk '{print $2,$3}' | awk 'NR==3{print}' | awk '{print $1}')
MAX=$(/usr/bin/quota | awk '{print $2,$3}' | awk 'NR==3{print}' | awk '{print $2}')
x=$CURRENT
y=$MAX
z=$((x*100/y))

THRESHOLD=60

if [ "$z" -gt "$THRESHOLD" ] ; then
  /usr/sbin/sendmail example@example.com << EOF
Subject: Disk space alert
Disk quota reached $THRESHOLD%. Current quota: $CURRENT
EOF
fi