🐚 Minishell

A simplified Unix shell implementation, developed as part of the 42 School curriculum.

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🧠 Introduction

Minishell is a project that aims to create a functional shell, inspired by Bash, with built-in command support, redirections, pipelines, variable expansions, and signal handling. It’s a great exercise in process management, parsing, memory allocation, and system calls in a POSIX environment.

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🚀 Features

✅ Mandatory:

• Prompt loop with input reading.
• Execution of commands with full path or via $PATH.
• Built-in commands: echo, cd, pwd, export, unset, env, exit.
• Redirections: >, <, >>, << (heredoc).
• Pipelines: ls | grep .c | wc -l.
• Environment variable expansion: $HOME, $?, etc.
• Quote handling: ' and " following POSIX rules.
• Signal handling (Ctrl-C, Ctrl-\, etc.).

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🧪 Usage

./minishell

A prompt (minishell$) will appear. You can now use built-in or system commands.

Examples:

minishell$ echo Hello World
minishell$ export PATH=/bin:/usr/bin
minishell$ ls -l | grep minishell > output.txt
minishell$ cat << EOF
> hello
> EOF

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📚 Implementation Highlights

🔤 Lexer & Parser

• Tokenizes the user input and builds a command structure.
• Supports syntax error checking and quote balancing.

🧩 Expansion

• Expands environment variables, $?, and handles double quotes correctly.

🔧 Execution Engine

• Manages child processes, file descriptors, pipes, and built-in execution without forking.
• Implements a heredoc manager and redirection handlers.

💥 Signals

• Restores terminal behaviors and handles SIGINT, SIGQUIT gracefully.
• Prevents crashes and zombie processes.

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👨‍💻 Authors

🧑‍🎓 Tharushan – utharushan 🧑‍🎓 El Bachir – ebella