SysMon 🖥️

A lightweight, real-time Linux system monitor built in modern C++17 with zero external runtime dependencies (except ncurses).

Built for accurate metrics, stable process behavior, and clean terminal UX .

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What to notice in the demo:

• Selection sticks to the same PID even while sorting changes
• CPU usage updates smoothly using delta sampling (no spikes/jumps)
• Clean window layout with stable rendering (minimal flicker)

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Why SysMon?

• Stable process tracking — selection follows the same PID even during live sorting and updates
• Accurate CPU measurement — delta-based calculation avoids misleading spikes
• Correct disk usage — matches real system availability (df -h behavior)
• Clean, predictable layout — structured ncurses UI for readability
• Direct kernel data access — reads from /proc and statvfs, no shell utilities

Summary: SysMon is built for correctness, stability, and clarity, not just displaying stats.

Overview

SysMon is a terminal-based system monitor built from scratch in C++17. It reads directly from Linux kernel interfaces instead of relying on external tools like top, ps, or df.

Focus areas:

• /proc parsing
• CPU delta sampling
• Memory correctness using MemAvailable
• Disk accounting using statvfs
• Real-time UI rendering with ncurses

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Core Features

System Metrics

• CPU usage (user, system, idle, iowait, IRQ)
• Memory usage using accurate availability model
• Disk usage aligned with df -h
• System uptime
• Network I/O per interface

Process Management

• Full process list (PID, CPU%, memory, state)
• Sorting (CPU / Memory / PID)
• Scrollable navigation
• Kill process support (K)
• Kernel thread filtering
• PID-stable selection across re-sorts

TUI

• Window-based layout
• Color-coded usage bars
• Pause-on-scroll behavior
• Help overlay (H)
• Terminal resize handling

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Performance

• Refresh interval: 1s
• CPU usage: ~3–5% (idle system)
• Memory usage: ~5–6 MB
• Consistent real-time updates with low overhead

• Direct kernel reads (/proc, statvfs), no subprocess calls

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How It Works (Key Concepts)

CPU Usage

cpu_usage% = (1 - idle_delta / total_delta) * 100

Memory

used = MemTotal - MemAvailable

Disk

used  = (f_blocks - f_bfree) * f_frsize
free  = f_bavail * f_frsize

Process CPU%

process_cpu% = (proc_delta / total_cpu_delta) * 100

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Installation

Requirements

• C++17 compiler
• CMake
• ncurses

Build

git clone https://github.com/riteshdhurwey/SysMon.git
cd SysMon
mkdir build && cd build
cmake ..
make

Install

sudo make install

Run

sysmon

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Project Structure

sysmon/
├── include/
├── src/
└── tests/

Modular design with separate components for CPU, memory, process, network, and UI.

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Roadmap

• Detailed memory view
• Disk I/O stats
• Network graphs
• Process filtering
• Custom refresh intervals
• Metrics export

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Contributing

Contributions are welcome. See CONTRIBUTING.md.

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Author

Ritesh Dhurwey LinkedIn · GitHub