Nginx Log Analyzer (Shell Script)

A simple command-line tool written in Bash to analyze Nginx access logs and extract useful insights such as the most active IPs, requested paths, response status codes, and user agents.

This project is designed to practice basic shell scripting and Unix text-processing tools like awk, sort, uniq, grep, sed, and cut. More about this project roadmap can be found here: Roadmap.sh Project Page

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📌 Features

The script analyzes an Nginx access log file and displays:

• Top 5 IP addresses with the most requests
• Top 5 most requested paths
• Top 5 response status codes
• Top 5 user agents

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📂 Project Structure

nginx-log-analyzer/
│
├── analyze_logs.sh        # Main shell script
├── access.log             # Nginx access log file
├── README.md              # Project documentation
└── output/                # (Optional) generated reports

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📄 Log Format Assumption

The script assumes a standard Nginx combined access log format, for example:

45.76.135.253 - - [10/Oct/2025:13:55:36 +0000]
"GET /api/v1/users HTTP/1.1" 200 1234
"[https://example.com](https://example.com)"
"Mozilla/5.0 (Windows NT 10.0; Win64; x64)"

Fields analyzed include:

• IP address
• Request method and path
• HTTP status code
• User agent

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🚀 Usage

1. Make the script executable

chmod +x analyze_logs.sh

2. Run the script

./analyze_logs.sh access.log

3. (Optional) Save output to a file

./analyze_logs.sh access.log > output/report.txt

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🧾 Sample Output

Top 5 IP addresses with the most requests:
45.76.135.253 - 1000 requests
142.93.143.8 - 600 requests
178.128.94.113 - 50 requests
43.224.43.187 - 30 requests
178.128.94.113 - 20 requests

Top 5 most requested paths:
/api/v1/users - 1000 requests
/api/v1/products - 600 requests
/api/v1/orders - 50 requests
/api/v1/payments - 30 requests
/api/v1/reviews - 20 requests

Top 5 response status codes:
200 - 1000 requests
404 - 600 requests
500 - 50 requests
401 - 30 requests
304 - 20 requests

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🛠 Tools & Commands Used

• awk – field extraction and text processing
• sort – sorting data
• uniq – counting unique values
• grep – pattern matching
• sed – text transformation
• cut – column extraction
• head – limiting output

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🎯 Learning Objectives

• Practice Unix shell scripting
• Understand Nginx access log structure
• Gain confidence using command-line text processing tools
• Build reusable CLI utilities

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🔧 Possible Enhancements

• Support custom log formats
• Add CSV or JSON output
• Filter logs by date/time range
• Add argument flags (e.g. --ips, --paths)
• Dockerize the script for portability

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