Minishell

A small Unix shell in C focused on parsing, builtins, pipes, redirections and signal handling.

parsing, execve, pipes, redirections, heredoc, builtins, environment, signals

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📌 Overview

Minishell is a project developed as part of the 42 curriculum.

This repository implements an interactive shell loop based on readline, a parsing layer that builds command and redirection structures, and an execution layer that dispatches builtins, external commands, pipes and redirections.

This project focuses on:

• interactive command reading and shell loop management
• quote-aware parsing and token organization
• process creation with fork, execve and wait
• file descriptor management for pipes, redirections and heredocs

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✨ Features

• ✅ Interactive prompt with readline history support
• ✅ Builtins: echo, cd, pwd, export, unset, env, exit
• ✅ Pipe execution for chained commands
• ✅ Redirections: <, >, >> and <<
• ✅ Signal handling for interactive mode and heredoc interruption
• ⚠️ Current parser design only exposes command, pipe and redirection tokens, so control operators such as &&, || or subshells are not implemented in this repository

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🧠 Concepts Covered

This project covers the following concepts:

• linked-list based token and redirection structures
• quote-aware string parsing
• environment duplication and mutation
• process lifecycle management
• file descriptor duplication with dup and dup2
• manual memory management and cleanup paths

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🛠️ Build

Clone the repository and compile the project:

git clone git@github.com:Middle-555/minishell.git
cd minishell
make

Available Makefile rules:

make
make clean
make fclean
make re

Additional notes:

• The repository also provides a make rapide target for a quieter build.
• The build links against readline with -lreadline.

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🚀 Usage

Run the program with:

./minishell

Examples

./minishell
echo "hello from minishell"
ls -l | grep minishell > out.txt
cat << EOF
heredoc line
EOF

Usage notes:

• main expects no extra CLI arguments and exits immediately if argc != 1.
• Ctrl-D exits the shell and prints exit.
• Once the prompt is open, commands are entered interactively inside minishell.

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📂 Project Structure

.
├── Makefile
├── include/
│   ├── minishell.h
│   └── utils/
│       ├── ft_printf/
│       ├── gnl/
│       └── libft/
├── srcs/
│   ├── builtin/
│   ├── envp/
│   ├── exec/
│   ├── parsing/
│   └── main.c
├── LICENSE
├── template.md
└── README.md

Structure Details

• include/ : main project headers and shared declarations
• srcs/ : application source files grouped by responsibility
• srcs/builtin/ : builtin command implementations and builtin dispatching
• srcs/parsing/ : tokenization, quote handling, expansion logic and redirection parsing
• srcs/exec/ : command execution, pipes, redirections, heredocs and signal flow
• include/utils/ : local utility libraries (libft, ft_printf, get_next_line)

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⚙️ Project Constraints

This repository is clearly organized around the 42 Minishell project scope:

• written in C
• centered on an interactive shell executable named minishell
• structured around parsing, execution, environment handling and builtins
• relies on manual memory management
• uses GNU Readline for the prompt layer

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🧪 Testing

Testing in this repository is mainly manual:

• interactive command execution checks
• builtin behavior checks
• pipeline and redirection scenarios
• heredoc and signal interruption scenarios
• environment mutation and exit status checks

Manual test examples

./minishell
echo "test" | cat
cat << EOF
hello
EOF

Memory checks

valgrind --leak-check=full --track-fds=yes ./minishell

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📖 What I Learned

This kind of project helps improve in the following areas:

• separating parsing concerns from execution concerns
• reasoning about processes and file descriptors
• handling shell edge cases around quotes, pipes and redirections
• cleaning dynamic allocations reliably in error and exit paths

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🚧 Possible Improvements

Although the project already covers the core minishell mechanics, several improvements are possible:

• replace Linux-specific headers with a more portable alternative
• add an automated regression test suite
• extend the parser to support more shell grammar features
• align edge-case behavior even more closely with Bash semantics

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👤 Authors

• Yoan Onieva
• Gauthier Esteve
• Kévin Pourcel
• Adrien Cabarbaye

📄 License

This project is distributed under the MIT license. See LICENSE.