🐚 Minishell

A lightweight Bash-compatible shell built in C

🧠 System Architecture

_{Executor-oriented logic flow (Design by workani)}

Minishell is built around a recursive execution tree that cleanly separates parsing from execution. This architecture enables unlimited pipe depth while keeping process control predictable and robust.

Execution flow

1. Lexing and Parsing: User input is tokenized and transformed into an Abstract Syntax Tree (AST).
2. Tree Traversal: The execution engine walks the AST, resolving pipes, redirections, and built-in commands.
3. Process Orchestration: Processes are forked, signals are configured, and I/O is redirected before handing control to execve.

✨ Supported Features

Command execution

• External commands via PATH using execve.
• Built-ins executed in-process when required.
• Correct exit status propagation ($?).

Pipelines

• Unlimited pipe depth using an AST-based executor.
• Proper file descriptor management.
• Built-ins and external commands mixed safely.

Redirections

• <, >, >>, << (heredoc with delimiter handling).
• Redirections resolved per AST node.

Quoting & expansion

• Single ' and double " quotes with Bash-like behavior.
• $VAR and $? expansion.
• Correct expansion order.

Signals & interaction

• ctrl-C resets prompt.
• ctrl-D exits.
• ctrl-\ ignored.
• Isolated signal handling for parent and children.

Built-ins

• echo -n, cd, pwd, export, unset, env, exit.

🛠️ Credits

• workani (Backend & Stability)

  • Project architecture and initial research.
  • Core execution loop: pipes, forks, and process management.
  • Memory safety and leak patching.

• mbondare (Parser & Signals)

  • Lexer and parser implementation.
  • Signal handling and interactive prompt.

• Joint Effort

  • Redirections, executor integration, and fixing edge cases.

🚀 Usage

Build:

make

Run:

./minishell

🧪 Testing

You can launch the verification suite shown above by following these steps:

1. Clone repository:

   git clone https://github.com/LucasKuhn/minishell_tester

2. Run:

   cd minishell_tester
   ./tester