🐚 42sh – A Unix Shell Inspired by TCSH

42sh is a custom Unix shell written in C as part of the EPITECH curriculum. Inspired by tcsh, this project aims to recreate a powerful, interactive command-line interface, complete with many built-in features, scripting capabilities, and user-friendly enhancements.

✨ Features

• Built-in commands:
  • cd, echo, exit, alias, setenv, unsetenv, env, printenv, which, where, repeat, yes, termname, expr, and more...
• Redirections:
  • Input/output redirection support: >, <, >>, << (here-documents)
• Pipelines:
  • Command chaining using pipes (|)
• Globbing:
  • Wildcard expansion (*, ?, etc.)
• Job control:
  • Background job handling with & fg bg Ctrl+Z
• History:
  • Command history navigation using arrow keys
• Interractive reverse search:
  • Search in the history with Ctrl+R
• Line editing:
  • Interactive line editing and cursor movement
• Auto completion:
  • Interactive auto completion with TAB
• Git integration:
  • Dynamic prompt with branch name, ahead and behind indicator
• Alias system:
  • Define and expand custom aliases
• Environment variables:
  • Manage the shell’s environment
• And more...

⚙️ Build & Run

git clone https://github.com/Savapitech/42sh.git
cd 42sh
make
./42sh

• Requires a POSIX-compliant system and a C compiler (tested with gcc on Linux).

📁 Project Structure

42sh/
├── include/            # Header files
├── src/                # Shell source code
├── ulib/               # Custom utility libraries
├── validation_tests.py # Functional tests
├── Makefile            # Build system
└── README.md           # You're reading it!

🧠 Concepts & Architecture

• Lexer/Parser: Tokenizes user input into an Abstract Syntax Tree (AST)
• Executor: Traverses the AST to execute commands
• Builtins: Custom implementation of standard shell commands

🧪 Testing

You can run the test suite using:

make tests_run

(Requires python3)

❄️ Nix Support

This project provides full support for Nix:

• You can run the shell directly with:

nix run github:Savapitech/42sh

• If you are working on the project, a development environment is available via the flake:

nix develop

This gives you access to a reproducible devShell with all required dependencies.

🛠️ Development Notes

Written in C99

Follows the EPITECH coding style

No memory leaks (only if no errors occured)

Handles signals (e.g., Ctrl+C, Ctrl+D)

Compatible with tcsh-style interactive behavior

📜 License

This project is part of the Epitech curriculum and is shared for educational purposes.

👥 Authors

@savalet, @tekClovis, @Arthur-gtr, @Titouanhct, @eiffis