Lifo

A tiny Linux-like operating system, written in TypeScript, that runs anywhere JavaScript does -- a browser tab, a Node.js process, a serverless function. Not a VM, not an emulator -- a clean-room reimplementation of Unix in TypeScript, where the JS runtime is the kernel and its APIs are the system calls.

┌──────────────────────────────────────────────────┐
│                  Terminal UI                      │  xterm.js + Tokyo Night theme
├──────────────────────────────────────────────────┤
│                    Shell                          │  bash-like interpreter
├──────────────────────────────────────────────────┤
│            Command Registry / $PATH              │  ES module command map
├───────────┬────────────┬─────────────────────────┤
│ Coreutils │ Net Cmds   │ User Packages           │  each cmd = async function
├───────────┴────────────┴─────────────────────────┤
│          Node.js Compatibility Layer             │  thin wrappers over OS APIs
├──────────────────────────────────────────────────┤
│           Virtual Filesystem (VFS)               │  in-memory + IndexedDB persistence
├──────────────────────────────────────────────────┤
│              Kernel API Layer                    │  unified browser API wrappers
├──────────────────────────────────────────────────┤
│               Browser APIs                       │  fetch, streams, OPFS, etc.
└──────────────────────────────────────────────────┘

Getting Started

pnpm install
pnpm dev

Open http://localhost:5173 in a modern browser. You'll be greeted with a fully functional terminal.

pnpm build        # Production build
pnpm test         # Run test suite
pnpm typecheck    # Type check without emitting

What's Inside

Kernel

• Virtual Filesystem (VFS) -- synchronous in-memory INode tree with full POSIX-like semantics (read, write, stat, mkdir, symlinks, hard links, permissions)
• Virtual Providers -- /proc exposes system info (uptime, meminfo, cpuinfo, version) and /dev provides device files (null, zero, random, urandom)
• Persistence -- IndexedDB-backed filesystem persistence with serialization/deserialization of the entire INode tree

Shell

A bash-like shell with:

• Full lexer/parser/interpreter pipeline producing an AST
• Pipes (ls | grep foo | wc -l), redirects (>, >>, <, 2>, &>)
• Logical operators (&&, ||), sequences (;), background (&)
• Variable expansion ($VAR, ${VAR:-default}), command substitution ($(...))
• Glob expansion (*.txt, **/*.js), tilde expansion (~), brace expansion ({a,b,c})
• Tab completion for commands, files, and directories
• Command history with reverse search
• Job control (Ctrl+C, fg, bg, jobs)
• Builtins: cd, pwd, export, alias, source, read, test, echo, and more

60+ Commands

Category	Commands
Filesystem	ls, cat, cp, mv, rm, mkdir, rmdir, touch, ln, stat, find, tree, du, df, chmod, file, basename, dirname, realpath, mktemp
Text	grep, sed, awk, head, tail, sort, uniq, wc, cut, tr, diff, nl, rev
I/O	printf, tee, xargs, yes
Network	curl, wget, ping, dig
System	ps, top, kill, env, uname, whoami, hostname, uptime, free, date, cal, bc, sleep, watch, which, man, help
Archive	tar, gzip, gunzip, zip, unzip
Runtime	node (run JS with Node.js compat layer), pkg (package manager)

Node.js Compatibility Layer

Run JavaScript files with node script.js or node -e "code". The compatibility layer maps 15 Node.js standard library modules to browser APIs:

fs, path, events, buffer, util, os, process, http, child_process, stream, url, timers, crypto, console

Package Manager

pkg install <url>    # Install a package from URL
pkg remove <name>    # Uninstall a package
pkg list             # List installed packages
pkg info <name>      # Show package details

Filesystem Hierarchy

/
├── home/user/          # User home directory ($HOME)
├── tmp/                # Temporary files (in-memory)
├── etc/                # System configuration
├── var/log/            # System logs
├── usr/bin/            # Installed package binaries
├── proc/               # Virtual: system info (cpuinfo, meminfo, uptime)
├── dev/                # Virtual: devices (null, zero, random, urandom)
└── bin/                # Core commands

Tech Stack

• TypeScript (strict mode, ESM throughout)
• Vite for builds
• xterm.js + WebGL addon for terminal rendering
• Vitest for testing
• Target: Chrome 110+, Firefox 110+, Safari 16.4+

Project Structure

src/
├── main.ts              # Boot sequence
├── kernel/              # VFS, persistence, virtual providers
├── shell/               # Lexer, parser, interpreter, expander, completer
├── commands/            # All 60+ commands organized by category
├── node-compat/         # Node.js standard library shims
├── pkg/                 # Package manager
├── terminal/            # xterm.js wrapper
└── utils/               # Path, args, glob, colors, encoding, archive
tests/                   # Mirrors src/ structure with full coverage

Related projects

Lifo is built by the team behind RapidNative — AI that generates production-ready React Native apps and UIs from a prompt — alongside these open-source tools:

Project	What it is
RapidNative	AI that generates production-ready React Native apps and UIs from a prompt
tinbase	A Supabase-compatible backend without Docker — one process, real Postgres, runs in the browser
ORCHD	A multi-tenant workload orchestrator — per-tenant workloads that sleep when idle and wake on the next request
jetplane	A Metro plugin and a thin dev server for Expo — many dev environments per machine

See them all on rapidnative.com/open-source.

License

MIT