monitor-disk.sh

df -PH | grep -vE '^Filesystem|none|cdrom' | awk '{ print $5 " " $1 }' | while read -r output;

do
  echo "$output"
  usep=$(echo "$output" | awk '{ print $1}' | cut -d'%' -f1  )
  partition=$(echo "$output" | awk '{ print $2 }' )

  if [ "$usep" -ge 90 ]; then
    echo "Running out of space \"$partition ($usep%)\" on $(hostname) as on $(date)" |
    mail -s "Alert: Almost out of disk space $usep%" -r system@server sendto@email.com
  fi
done