Disk Space Alert Script

Overview

This script monitors disk usage across all mounted filesystems and sends email alerts when usage exceeds a configurable threshold. Ideal for cron job automation.

The Script

#!/bin/bash
# Disk Space Alert Script
# Usage: ./disk-alert.sh [threshold] [email]

THRESHOLD=\${1:-85}
EMAIL=\${2:-"[email protected]"}
HOSTNAME=$(hostname)
DATE=$(date '+%Y-%m-%d %H:%M:%S')

# Get disk usage, skip header and tmpfs
df -h | awk 'NR>1 && !/tmpfs/ {print $5, $6}' | while read usage mount; do
    # Remove % sign and compare
    usage_int=\${usage%\%}

    if [ "$usage_int" -ge "$THRESHOLD" ]; then
        echo "WARNING: $mount is \${usage} full on $HOSTNAME at $DATE" | \\
            mail -s "Disk Alert: $HOSTNAME - $mount at \${usage}" "$EMAIL"

        # Also log locally
        logger -t disk-alert "WARNING: $mount is \${usage} full"
    fi
done

echo "Disk check completed at $DATE"

Installation

1. Save the script:

sudo vim /usr/local/bin/disk-alert.sh
sudo chmod +x /usr/local/bin/disk-alert.sh

1. Add to crontab (check every hour):

# Edit root's crontab
sudo crontab -e

# Add this line (runs every hour)
0 * * * * /usr/local/bin/disk-alert.sh 85 [email protected]

Configuration Options

Requirements

• `mailutils` or `mailx` for email sending
• Proper mail configuration (postfix, sendmail, etc.)