How to check disk level in Linux and mail an alert

DiskCheck.sh

ADMIN="adminEmail@yourDomain.com"
# set alert-level 90 % standard
ALERT=10
df -h | grep -vE '^Filesystem|tmpfs|cdrom' | awk '{ print $5 " " $6 }' | while read output;
do
  usep=$(echo $output | awk '{ print $1}' | cut -d'%' -f1  )
  partition=$(echo $output | awk '{ print $2 }' )
  if [ $usep -ge $ALERT ]; then
    echo "space low on \"$partition ($usep%)\", on server $(hostname) at $(date)" |
     mail -s "Alert: Free space low, $usep % used on $partition" $ADMIN
  fi
done

SimplerDiskCheck.sh

#!/bin/bash
CURRENT=$(df / | grep / | awk '{ print $5}' | sed 's/%//g')
THRESHOLD=90

if [ "$CURRENT" -gt "$THRESHOLD" ] ; then
    mail -s 'Disk Space Alert' sysadmin@yourdomain.com << EOF
Your root partition remaining free space is critically low. Used: $CURRENT%
EOF
fi