Project 8: Terminal Multiplexer (Mini-tmux)

A terminal multiplexer like tmux/screen that lets you detach/reattach sessions, with multiple panes in one terminal.

Quick Reference

Attribute Value
Primary Language C
Alternative Languages Rust, Go
Difficulty Level 3: Advanced (The Engineer)
Time Estimate 4-6 weeks
Knowledge Area Multiplexing / Client-Server / PTY
Tooling Terminal Multiplexer
Prerequisites Project 7

What You Will Build

A terminal multiplexer like tmux/screen that lets you detach/reattach sessions, with multiple panes in one terminal.

Why It Matters

This project builds core skills that appear repeatedly in real-world systems and tooling.

Core Challenges

  • Client-server architecture → Detach/reattach requires separate processes
  • Multiple PTYs → Each pane has its own PTY
  • Virtual rendering → Render shells to buffers, composite to real terminal
  • Pane layout → Splitting, resizing, handling geometry
  • Re-rendering → Diff-based updates for efficiency

Key Concepts

  • tmux Architecture: tmux source code (server.c, window.c, screen.c)
  • Unix Domain Sockets: “Advanced Programming in the UNIX Environment” Chapter 17 - Stevens & Rago
  • Virtual Terminal: How tmux Works

Real-World Outcome

$ ./minitux new-session
# Creates a new session, attaches to it

$ ./minitux split-horizontal
┌─────────────────────────────────────┐
│ $ _                                 │
├─────────────────────────────────────┤
│ $ _                                 │
└─────────────────────────────────────┘

$ ./minitux detach
[detached from session 0]

# Close terminal, SSH again...

$ ./minitux attach
# Your session is restored!

Implementation Guide

  1. Reproduce the simplest happy-path scenario.
  2. Build the smallest working version of the core feature.
  3. Add input validation and error handling.
  4. Add instrumentation/logging to confirm behavior.
  5. Refactor into clean modules with tests.

Milestones

  • Milestone 1: Minimal working program that runs end-to-end.
  • Milestone 2: Correct outputs for typical inputs.
  • Milestone 3: Robust handling of edge cases.
  • Milestone 4: Clean structure and documented usage.

Validation Checklist

  • Output matches the real-world outcome example
  • Handles invalid inputs safely
  • Provides clear errors and exit codes
  • Repeatable results across runs

References

  • Main guide: TERMINAL_EMULATOR_DEEP_DIVE_PROJECTS.md
  • “Advanced Programming in the UNIX Environment” by Stevens & Rago