#!/bin/bash
THRESHOLD=80
df -H | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $1 }' | while read output;
do
  usage=$(echo $output | awk '{ print $1}' | cut -d'%' -f1)
  partition=$(echo $output | awk '{ print $2 }')
  if [ $usage -ge $THRESHOLD ]; then
    echo "WARNING: Disk $partition is at ${usage}% capacity"
  fi
done