Build Real-World Shell Automation Projects

#!/bin/sh
set -e

LOG_FILE="/var/log/nginx/access.log"
REPORT_FILE="/tmp/security_report_$(date +%F).txt"

# Defensive Validation
if [ ! -f "$LOG_FILE" ]; then
    echo "ERROR: Log file missing!" >&2
    exit 1
fi

echo "Initiating Forensic Log Analysis..."

# Create the report header
echo "=== TOP 5 SUSPICIOUS IP ADDRESSES ===" > "$REPORT_FILE"
echo "Count | IP Address" >> "$REPORT_FILE"
echo "-----------------------------------" >> "$REPORT_FILE"

# The Text Processing Pipeline
# 1. awk prints the 1st column (IPs)
# 2. sort groups them alphabetically
# 3. uniq -c counts the occurrences
# 4. sort -nr ranks them highest to lowest numerically
# 5. head -n 5 grabs the top 5 lines
awk '{print $1}' "$LOG_FILE" | sort | uniq -c | sort -nr | head -n 5 >> "$REPORT_FILE"

echo "Analysis complete. Report successfully generated at $REPORT_FILE."
cat "$REPORT_FILE"

#!/bin/sh

# Configuration
DISK_THRESHOLD=90
SERVICE_TO_HEAL="apache2"
LOG_DEST="/var/log/system_health.log"

TIMESTAMP=$(date +"%Y-%m-%d %H:%M:%S")

# Extract the Disk Usage percentage using df, awk, and sed
CURRENT_USAGE=$(df -h / | awk '{print $5}' | tail -n 1 | sed 's/%//g')

if [ "$CURRENT_USAGE" -ge "$DISK_THRESHOLD" ]; then
    echo "[$TIMESTAMP] CRITICAL: Disk Usage is at ${CURRENT_USAGE}%. Executing self-healing protocol..." >> "$LOG_DEST"
    
    # Attempt to restart the service to clear temporary cache logs safely
    sudo systemctl restart "$SERVICE_TO_HEAL"
    
    if [ $? -eq 0 ]; then
        echo "[$TIMESTAMP] RECOVERY: $SERVICE_TO_HEAL restarted successfully to clear cache." >> "$LOG_DEST"
    else
        echo "[$TIMESTAMP] FATAL: Failed to restart service. Manual intervention absolutely required!" >> "$LOG_DEST"
    fi
else
    # Silent success for cron (Execute a colon which does nothing)
    : 
fi

#!/bin/sh
set -e
set -u

SOURCE_DIR="/var/www/html"
BACKUP_DIR="/archive/web_backups"
DATE=$(date +"%Y%m%d_%H%M%S")
BACKUP_FILE="${BACKUP_DIR}/website_backup_${DATE}.tar.gz"

# 1. Self-Healing Environment Setup
if [ ! -d "$BACKUP_DIR" ]; then
    mkdir -p "$BACKUP_DIR"
    chmod 700 "$BACKUP_DIR" # Restrict access to root only for security
fi

# 2. Trap for Cleanup on Failure
cleanup() {
    echo "ERROR: Backup failed unexpectedly! Cleaning up partial files..." >&2
    rm -f "$BACKUP_FILE"
}
# Catch Errors or Ctrl+C
trap cleanup ERR SIGINT

# 3. Execution
echo "Starting secure backup sequence..."

# Compress securely, discarding standard output to keep cron quiet, but allowing errors to trigger the trap
tar -czf "$BACKUP_FILE" "$SOURCE_DIR" > /dev/null

echo "SUCCESS: Backup securely stored at $BACKUP_FILE."

# Clear the trap since we succeeded naturally
trap - ERR SIGINT