MINIMON - Linux Resource Monitoring Tool

Author: Beyza Komiş Student Number: B231202072

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📌 Project Overview

MINIMON is a lightweight Linux system resource monitoring tool built using C++. It retrieves and reports detailed information about CPU, memory, disk, network, and processes. Reports are printed to the console and also exported as JSON and CSV files for further analysis.

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⚙️ Platform & Environment

Important Note: Due to limitations on running virtual machines on my Windows machine, I used Windows Subsystem for Linux (WSL) to emulate a Linux environment. This enabled full compatibility with Linux commands and virtual file structures like /proc.

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📁 Project Structure

minimon/
├── README.md
├── Makefile
├── main.cpp                // Entry point with userInput() function
├── minimon                 // Compiled binary
├── core/
│   ├── collector.h/.cpp    // Collect data from Linux system
│   ├── analyzer.h/.cpp     // Analyze resource trends (optional use)
│   ├── reporter.h/.cpp     // Print to console / Export to CSV & JSON
├── ui/
│   ├── cli.h/.cpp          // Command-line interface
├── csvFiles/
│   ├── cpu_usage.csv
│   ├── memory_info.csv
│   ├── disk_info.csv
│   ├── network_info.csv
│   └── top_process.csv
├── jsonFiles/
│   ├── cpu_usage.json
│   ├── memory_info.json
│   ├── disk_info.json
│   ├── network_info.json
│   └── top_process.json

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🛠️ Build Instructions

Prerequisites

• Linux or WSL (Windows Subsystem for Linux)
• g++ with C++17 support
• make

Build

make

Run

./minimon [cpu|mem|disk|net|top N|conn PID|check PID]

Example Usage

./minimon cpu      # Shows CPU usage
./minimon mem      # Shows memory info
./minimon top 5    # Shows top 5 CPU-consuming processes
./minimon conn 123 # Shows network connections for process with PID 123

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🧩 Features

1. Resource Monitoring Functions

• vector<ProcessInfo> collectProcesses(int n)
• CPUUsage getCPUUsage()
• MemoryInfo getMemoryInfo()
• DiskInfo getDiskInfo()
• NetworkInfo getNetworkInfo()
• vector<ConnectionInfo> getConnectionInfo(int pid)
• long getProcessRAMUsage(int pid)
• float getProcessCPUUsage(int pid)

2. Reporting Functions

• Print to console, CSV, and JSON
• reportCPUUsage()
• reportMemoryInfo()
• reportDiskInfo()
• reportNetworkInfo()
• reportTopProcess(int n)
• reportConnectionInfo(int pid)

3. Simple Command-Line Interface

Handled using:

void userInput(int argc, char *argv[]);

Provides user feedback for invalid input and guides correct usage.

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🧠 Logic Behind Data Collection

Most data is collected by reading from Linux virtual filesystems like /proc. Here's a breakdown of the logic behind the function collectProcesses(int n):

• Iterate over /proc directories.

• Filter numeric names (valid PIDs).

• Open /proc/[pid]/stat to extract CPU time.

• Use helper functions to get:

  • RAM usage
  • Process status

• Store in ProcessInfo struct.

• Sort by CPU time and return top n.

Other resource functions follow a similar pattern of reading, filtering, parsing, and structuring.

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🧪 Analyzer Module

Although included, the analyzer functions had limited use due to the small scope. Example functions:

• CPUUsage calculatePrevAndNewUsage(...)
• bool isCPUUsageIncreased(...)
• vector<ProcessInfo> sortProcess(...)

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📂 Files Used for Monitoring

File Path	Purpose
/proc/[pid]/stat	Process stats
/proc/[pid]/status	Process state
/proc/[pid]/cmdline	Command line
/proc/meminfo	Memory and swap info
/proc/stat	CPU stats
/proc/diskstats	Disk I/O stats
/proc/net/dev	Network device info
/proc/net/tcp	TCP connections
/proc/net/udp	UDP connections

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🧰 Libraries Used

• <dirent.h> - For directory handling (/proc)
• <arpa/inet.h> - IP/port parsing
• <unistd.h> - Sleep and system config
• <sys/statvfs.h> - Disk stats

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🔎 Filtering Logic

Filtering is applied in several layers:

• Memory Info: Filters "MemTotal", "MemFree", "MemAvailable"
• Disk Info: Filters lines starting with "sda"
• Network Info: Filters known interfaces: eth0, wlan0, enp0s3

This ensures that only relevant data is processed and displayed.

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❗ Limitations

• Requires a Linux environment. Windows users must use WSL.
• Analyzer functions were not fully leveraged due to project simplicity.
• Some edge-case processes may not return full data.

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📌 Final Notes

MINIMON demonstrates how to build a modular, console-based system monitoring tool by leveraging the Linux /proc virtual filesystem, C++ structs/vectors, and file-based I/O. Though simplified, it sets a strong foundation for more advanced real-time monitoring tools.