# rtop

**Author:** retoor <retoor@molodetz.nl>

A terminal-based system monitoring tool written in C that displays comprehensive system statistics in a tabbed, auto-refreshing interface. rtop is designed as a lightweight alternative to htop with no external dependencies beyond the standard C library.

## Features

- Tabbed interface with 5 dedicated views (CPU, Memory, Network, Disk, Process)
- Real-time system monitoring with configurable refresh interval
- Auto-rotate tabs at configurable interval
- Pause mode for copy/paste operations
- Per-core CPU utilization with temperature and frequency display
- Memory and swap usage statistics with task summary
- Process listing sorted by CPU or memory usage
- Network interface statistics with RX/TX rates and IP addresses
- Disk I/O statistics with IOPS
- Filesystem usage information
- Color-coded progress bars for utilization levels
- Terminal resize handling

## Requirements

- Linux operating system
- GCC compiler (C99 compliant)
- Make build system

## Building

```bash
make
```

The build produces a single binary `rtop` with minimal dependencies.

### Build Options

```bash
make clean      # Remove build artifacts
make debug      # Build with debug symbols
make install    # Install to /usr/local/bin (requires root)
```

## Usage

```bash
./rtop [OPTIONS]

Options:
  -d, --delay SECS   Update interval in seconds (default: 1.0)
  -r, --rotate SECS  Auto-rotate tabs every SECS seconds (0=off, default: 0)
  -s, --sort MODE    Sort by: cpu (default), mem
  -h, --help         Show help message
  -v, --version      Show version
```

### Examples

```bash
./rtop              # Run with default settings
./rtop -d 2         # Update every 2 seconds
./rtop -r 5         # Auto-rotate tabs every 5 seconds
./rtop -s mem       # Sort processes by memory usage
./rtop -d 0.5 -r 3  # Fast refresh with 3-second tab rotation
```

## Tabs

| Tab | Content |
|-----|---------|
| CPU | Per-core utilization bars, temperature, frequency, total usage |
| Memory | RAM/Swap usage, buffers/cache, task summary (running, sleeping, stopped, zombie) |
| Network | Interface list with IP addresses, RX/TX rates, total bytes transferred |
| Disk | Per-device I/O rates, IOPS, filesystem mount points with usage |
| Process | Detailed process list with PID, user, CPU%, MEM%, command |

## Controls

| Key | Action |
|-----|--------|
| Left/Right arrows | Switch between tabs |
| 1-5 | Jump directly to tab |
| ESC | Pause refresh (for copy/paste) |
| q / Q | Quit the application |
| Ctrl+C | Terminate |

## Technical Details

### Data Sources

All system information is read from the Linux `/proc` and `/sys` filesystems:

| Source | Information |
|--------|-------------|
| `/proc/stat` | CPU statistics |
| `/proc/meminfo` | Memory information |
| `/proc/[pid]/stat` | Process information |
| `/proc/net/dev` | Network statistics |
| `/proc/diskstats` | Disk I/O statistics |
| `/sys/class/thermal/` | Temperature sensors |
| `/sys/devices/system/cpu/` | CPU frequency |

### Performance

- Target CPU usage: <5%
- Startup time: <100ms
- Memory footprint: <10MB RSS

## Project Structure

```
rtop/
├── include/
│   ├── cpu.h
│   ├── disk.h
│   ├── display.h
│   ├── filesystem.h
│   ├── memory.h
│   ├── network.h
│   ├── process.h
│   ├── system.h
│   └── terminal.h
├── src/
│   ├── cpu.c
│   ├── disk.c
│   ├── display.c
│   ├── filesystem.c
│   ├── main.c
│   ├── memory.c
│   ├── network.c
│   ├── process.c
│   ├── system.c
│   └── terminal.c
├── Makefile
└── README.md
```

## License

This project is provided as-is for educational and personal use.