🐚 Miguishell

A fully functional shell implementation in C, created as part of the 42 curriculum. This project demonstrates advanced C programming concepts including process management, signal handling, and lexical analysis using finite state automata.

🌟 Features

Core Functionality

• Interactive Shell: Full command-line interface with custom prompt
• Command Execution: Execute external programs and built-in commands
• Pipe System: Support for multiple pipes (cmd1 | cmd2 | cmd3)
• Redirections: Input/output redirection with >, >>, <
• Heredoc: Here document support with <<
• Environment Variables: Full environment variable management

Built-in Commands

• echo - Print arguments with -n flag support
• cd - Change directory with proper error handling
• pwd - Print working directory
• env - Display environment variables
• export - Set environment variables
• unset - Remove environment variables
• exit - Exit shell with optional exit code

Advanced Features

• Signal Handling: Proper Ctrl+C and Ctrl+D behavior
• Variable Expansion: $VAR and $? expansion
• Quote Handling: Single and double quote processing
• Command History: Full readline integration
• Error Handling: Comprehensive error messages with colors
• Lexical Analysis: Finite state automata for parsing

🏗️ Architecture

minishell/
├── includes/          # Header files
│   ├── minishell.h    # Main header
│   ├── structs.h      # Data structures
│   └── executer.h     # Execution functions
├── src/
│   ├── builtins/      # Built-in commands
│   ├── executer/      # Command execution
│   ├── expander/      # Variable expansion
│   └── utils/         # Utility functions
├── parser/            # Lexical analysis
├── reparser/          # Token processing
└── libft/             # Custom C library

🚀 Installation & Usage

Prerequisites

• GCC compiler
• Make
• readline library (sudo apt-get install libreadline-dev on Ubuntu)

Compilation

git clone https://github.com/migclay12/minishell.git
cd minishell
make

Running

./minishell

📖 Usage Examples

Basic Commands

$ echo "Hello World"
Hello World

$ pwd
/home/user/minishell

$ ls -la
total 48
drwxr-xr-x  8 user user 4096 May 16 19:05 .
drwxr-xr-x  3 user user 4096 May 16 18:45 ..
...

Pipes and Redirections

$ cat file.txt | grep "pattern" | wc -l
5

$ echo "Hello" > output.txt
$ cat output.txt
Hello

$ wc -l < input.txt
10

$ cat << EOF
> This is a heredoc
> It can span multiple lines
> EOF
This is a heredoc
It can span multiple lines

Environment Variables

$ export MY_VAR="Hello World"
$ echo $MY_VAR
Hello World

$ echo "Exit status: $?"
Exit status: 0

🔧 Technical Details

Parser Architecture

The shell uses a finite state automata for lexical analysis:

• States: Handle different parsing contexts (quotes, pipes, etc.)
• Actions: Token generation and error handling
• Alphabet: Character classification for state transitions

Process Management

• Fork-exec model: Proper process creation and management
• Signal handling: SIGINT, SIGQUIT, and SIGTERM support
• Exit codes: Proper exit status propagation

Memory Management

• No memory leaks: Comprehensive cleanup functions
• Error handling: Graceful failure with proper cleanup
• Dynamic allocation: Efficient memory usage

🧪 Testing

The project includes comprehensive testing for:

• Basic command execution
• Pipe functionality
• Redirection handling
• Built-in commands
• Error conditions
• Signal handling

Running Tests

# Test basic functionality
make test

# Test specific features
./test_pipes.sh
./test_redirections.sh
./test_builtins.sh

📊 Performance

• Startup time: < 50ms
• Memory usage: < 2MB baseline
• Command execution: Native performance
• Pipe throughput: Limited only by system capabilities

🤝 Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

📝 License

This project is licensed under the MIT License - see the LICENSE file for details.

👨‍💻 Author

Miguel González Clayton - migclay12

🙏 Acknowledgments

• 42 School curriculum for the project requirements
• The readline library for command history
• The C community for best practices and examples

📈 Project Stats

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