minishell

Minishell - From Zero to Hero 🚀

Welcome to your Minishell journey! This README provides a full guide on what you need to learn and implement to successfully complete the mandatory part of the Minishell project.

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📚 What You Will Learn

By building Minishell, you’ll learn:

• How shells work internally
• Parsing and executing commands
• Managing processes and file descriptors
• Handling pipes and redirections
• Managing environment variables
• Implementing built-in commands
• Signal handling

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🧠 Step-by-Step Learning & Implementation Guide

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1. 🧵 Shell & Terminal Basics

• What is a shell and how does it work?
• Shells vs terminals
• Execution flow of a command like ls -l

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2. 🧠 C Programming Fundamentals

Make sure you're confident with:

• malloc, free, realloc
• String manipulation: strdup, strtok, strchr, strncmp
• File descriptors: read, write, open, close
• Understanding and using arrays of strings (char **)

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3. 🔄 Process Management

Key system calls:

• fork() - create a new process
• execve() - replace process image
• wait() / waitpid() - wait for child process
• exit() - return exit code

💡 Each command will be run in a child process using these calls.

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4. 🌍 Environment Variables

• Understand char **envp in main
• How to copy and modify environment variables
• Implement env, export, unset

You’ll maintain your own internal env list and update it as needed.

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5. 🧰 Built-in Commands

Implement these:

• echo (with -n)
• cd
• pwd
• export
• unset
• env
• exit

💡 Only cd, exit, and export must be run in the parent process.

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6. 🧹 Parsing & Tokenizing Input

You’ll write a custom parser to:

• Split input by spaces while respecting:
  • Quotes 'like this', "like this"
  • Environment variables: $HOME, $?
• Detect syntax errors
• Handle escape sequences and empty inputs

Example:

echo "Hello $USER" | grep "o" > output.txt