Overview

Log Analyzer is a command-line log analysis tool written in C that processes large log files efficiently using a streaming design. It reads log files line-by-line, classifies log levels, aggregates repeated error messages, and produces a concise summary report.

This project is intentionally built as a core engine that can later be reused by a graphical interface without modifying the analysis logic.

Version v1.0 represents a feature-complete, tested, and frozen CLI tool.

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What This Tool Does (v1.0)

1. Streaming Log File Processing

• Reads log files line by line
• Does not load the entire file into memory
• Suitable for very large log files

This ensures:

• Low memory usage
• Stable performance
• No risk of memory exhaustion

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2. Log Level Classification

The analyzer recognizes and counts the following log levels:

• INFO
• WARN
• ERROR

Each valid log entry contributes to:

• Total line count
• Individual severity counters

Invalid or malformed lines are safely ignored without crashing.

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3. Error Message Aggregation

• Error messages are grouped by exact message text

• Duplicate errors are counted

• Each unique error message stores:

  • Message text
  • Number of occurrences

This allows the tool to highlight recurring problems, not just raw error volume.

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4. Top-N Error Reporting

• Displays the most frequent error messages
• Supports configurable limits via CLI flags
• Errors are sorted by occurrence count (descending)

This helps identify root causes, not noise.

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5. Robust Command-Line Interface

The CLI supports:

• File path input

• Optional flags:

  • --errors-only
  • --top-errors N
  • --help
  • --version

The program validates arguments and exits cleanly on invalid input.

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6. Defensive Parsing & Error Handling

• Missing files are handled gracefully
• Empty files do not cause failures
• Invalid log lines are ignored safely
• No segmentation faults under normal or edge-case inputs

This makes the tool safe to run on unknown logs.

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Internal Architecture (v1.0)

The project follows a modular C design with strict separation of responsibilities:

Core Modules

• File Reader

  • Streams log lines from disk

• Parser

  • Converts raw log lines into structured entries

• Analyzer

  • Maintains counters and aggregates errors

• Reporter

  • Formats and prints final output

Each module is isolated through headers and does one job only.

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Build System

• Uses a Makefile
• Compiles each source file independently
• Produces a single CLI executable: loganalyzer

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Features (v1.0)

• Streaming log file analysis
• INFO / WARN / ERROR classification
• Error aggregation by message text
• Top-N most frequent errors
• Robust CLI argument parsing
• Safe handling of malformed input
• Stable performance on large files
• Windows-compatible command-line tool

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Non-Goals (v1.0)

The following are intentionally excluded from this version:

• No graphical user interface (GUI)
• No JSON or machine-readable output
• No multithreading
• No log file modification or writing
• No real-time log monitoring

These exclusions are deliberate to keep the core engine simple, stable, and reusable.

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Version Freeze Statement

This project is now frozen as:

loganalyzer v1.0 (CLI)

From this point forward:

• Only bug fixes are allowed
• No refactoring of working code
• No new features added
• Core analysis logic remains unchanged

Any future development (such as a GUI) will be built on top of this engine, not inside it.

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Intended Next Phase (Not Part of v1.0)

• Graphical user interface using a separate front-end layer
• Reuse of the existing C engine without modification

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Summary

Version v1.0 represents a complete, stable, and tested CLI log analysis tool written in standard C. It demonstrates real-world systems programming concepts including modular design, safe memory usage, and defensive input handling.

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✅ CLI Phase: COMPLETE

🔒 Status: FROZEN

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Features (v1.0)

• Streaming log file analysis
• INFO / WARN / ERROR classification
• Error aggregation by message
• Top-N most frequent errors
• Robust CLI argument parsing
• Handles large log files safely
• Windows-compatible CLI tool

Non-Goals (v1.0)

• No GUI
• No JSON output
• No multithreading
• No log file modification