send_full_disk_alert_mail.sh

#!/bin/bash

# Script that sends an alert email when any disk's used space is over a certain
# limit.
# The first parameter to this script is the min disk space usage percentage for
# when the alerts kicks in.
# The second parameter is the email address the alert message should be sent
# to.
#
# Can be configured in a crontab like this:
#
#     0 0 * * * send_full_disk_alert_mail 90 mail@example.com
#
# Based on: https://unix.stackexchange.com/a/84359/39618

message=$(df -h | awk -v ALERT="$1" '
    NR == 1 {next}
    $1 == "abc:/xyz/pqr" {next}
    $1 == "tmpfs" {next}
    $1 == "/dev/cdrom" {next}
    1 {sub(/%/,"",$5)}
    $5 >= ALERT {printf "%s is almost full: %d%%\n", $1, $5}
')

if [ -n "$message" ]; then
  echo "$message" | mail -s "Alert: Almost out of disk space" "$2"
fi