#!/bin/bash

# Configuration
DISK_PARTITION="/" # The disk partition to monitor (e.g., / or /var)
THRESHOLD=90 # Percentage threshold (e.g., 90 means 90% full)
ALERT_EMAIL="admin@example.com"
HOSTNAME=$(hostname)

# Get current disk usage percentage
USAGE=$(df -h "$DISK_PARTITION" | grep "$DISK_PARTITION" | awk '{print $5}' | sed 's/%//g')

if [[ -z "$USAGE" ]]; then
  echo "Error: Could not determine disk usage for $DISK_PARTITION. Check partition name."
  exit 1
fi

echo "Current disk usage for $DISK_PARTITION on $HOSTNAME: $USAGE%"

if (( USAGE > THRESHOLD )); then
  SUBJECT="CRITICAL ALERT: High Disk Usage on $HOSTNAME for $DISK_PARTITION"
  BODY="Disk usage for $DISK_PARTITION is at $USAGE%, which exceeds the threshold of $THRESHOLD%.
Please take action immediately.

Full disk usage report:
$(df -h "$DISK_PARTITION")"

  echo "Sending email alert to $ALERT_EMAIL..."
  echo -e "$BODY" | mail -s "$SUBJECT" "$ALERT_EMAIL"

  if [ $? -eq 0 ]; then
    echo "Alert email sent successfully."
  else
    echo "Error: Failed to send alert email."
  fi
else
  echo "Disk usage is within acceptable limits ($USAGE% < $THRESHOLD%). No alert sent."
fi