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 .

demo

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

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

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

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

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

Project Structure

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

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

Roadmap

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

Contributing

Contributions are welcome. See CONTRIBUTING.md.

Author

Ritesh Dhurwey LinkedIn · GitHub

SysMon

Install / Use

README