🐚 Minishell - Babuterm

A comprehensive Unix shell implementation recreating bash functionality

Features • Installation • Usage • Built-ins • Architecture

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📋 Table of Contents

• About
• Features
• Installation
• Usage
• Built-in Commands
• Advanced Features
• Architecture
• Project Structure
• Memory Management
• Signal Handling
• Testing
• Authors
• License

🎯 About

Minishell is a simplified shell implementation written in C as part of the 42 School curriculum. This project recreates the core functionality of bash, providing users with a command-line interface capable of executing commands, managing processes, handling I/O redirection, and implementing essential built-in commands.

The shell handles complex parsing, process management, signal handling, and memory management while maintaining compatibility with standard Unix shell behavior.

✨ Features

Core Shell Functionality

• 🔄 Interactive Command Execution - Execute system commands and built-ins
• 📝 Command History - Navigate through command history using arrow keys
• 🎨 Colored Prompt - Beautiful, informative prompt with color coding
• 🔍 Path Resolution - Automatic command path discovery
• 🧠 Memory Safe - Comprehensive memory management with no leaks

Advanced Parsing

• 🎭 Quote Handling - Support for single (') and double (") quotes
• 🔗 Pipe Operations - Chain commands with pipes (|)
• 📊 Variable Expansion - Environment variable substitution ($VAR)
• 🚫 Syntax Validation - Comprehensive input validation and error handling

I/O Redirection

• 📥 Input Redirection (<) - Redirect stdin from files
• 📤 Output Redirection (>) - Redirect stdout to files
• 📋 Append Mode (>>) - Append output to files
• 📄 Here Documents (<<) - Multi-line input with delimiters

Process Management

• 🔄 Pipeline Execution - Multi-command pipelines
• ⚡ Signal Handling - Proper SIGINT and SIGQUIT management
• 🎯 Exit Status - Accurate exit code handling
• 🧵 Fork Management - Efficient process creation and cleanup

🚀 Installation

Prerequisites

# Ubuntu/Debian
sudo apt-get update
sudo apt-get install build-essential libreadline-dev

# macOS
brew install readline

Build from Source

# Clone the repository
git clone [repository-url]
cd Babuterm

# Compile the project
make

# Run the shell
./minishell

Makefile Targets

make           # Build the project
make clean     # Remove object files
make fclean    # Remove object files and executable
make re        # Rebuild everything

💻 Usage

Basic Command Execution

# Start the shell
./minishell

# Execute commands
babuterm$ ls -la
babuterm$ echo "Hello, World!"
babuterm$ cat file.txt

Pipe Operations

# Chain commands with pipes
babuterm$ ls -la | grep ".c" | wc -l
babuterm$ cat file.txt | head -10 | tail -5

I/O Redirection

# Input redirection
babuterm$ wc -l < input.txt

# Output redirection
babuterm$ echo "Hello" > output.txt
babuterm$ ls -la >> log.txt

# Here documents
babuterm$ cat << EOF
This is a multi-line
input example
EOF

Variable Expansion

# Environment variables
babuterm$ echo $HOME
babuterm$ echo "User: $USER"
babuterm$ echo 'Literal: $HOME'  # No expansion in single quotes

🛠 Built-in Commands

Command	Description	Example
echo	Display text with optional -n flag	echo -n "Hello World"
cd	Change directory	cd /path/to/directory
pwd	Print working directory	pwd
export	Set environment variables	export VAR=value
unset	Remove environment variables	unset VAR
env	Display environment variables	env
exit	Exit the shell	exit [code]

Built-in Command Details

echo

babuterm$ echo "Hello World"           # Basic output
babuterm$ echo -n "No newline"         # Suppress newline
babuterm$ echo -n -n -n "Multiple -n"  # Multiple -n flags

cd

babuterm$ cd /home/user      # Absolute path
babuterm$ cd ..              # Parent directory
babuterm$ cd                 # Home directory
babuterm$ cd -               # Previous directory

export

babuterm$ export NAME=value     # Set variable
babuterm$ export PATH=$PATH:/new/path  # Modify PATH
babuterm$ export               # List all exported variables

🔧 Advanced Features

Quote Handling

• Single Quotes: Preserve literal values
• Double Quotes: Allow variable expansion
• Quote Removal: Automatic quote stripping in arguments

Error Handling

• Comprehensive syntax error detection
• Graceful handling of invalid commands
• Proper exit status propagation
• Memory cleanup on errors

Signal Management

• Ctrl+C (SIGINT): Interrupt current command
• Ctrl+\ (SIGQUIT): Ignored in interactive mode
• Ctrl+D (EOF): Exit shell gracefully

🏗 Architecture

Core Components

┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│   Input Parser  │───▶│  Command Parser │───▶│   Executor      │
│   (Lexical)     │    │   (Syntax)      │    │  (Execution)    │
└─────────────────┘    └─────────────────┘    └─────────────────┘
         │                       │                       │
         ▼                       ▼                       ▼
┌─────────────────┐    ┌─────────────────┐    ┌─────────────────┐
│ Quote Handler   │    │ Variable Expand │    │ Process Manager │
│ Error Validator │    │ Path Resolution │    │ Signal Handler  │
└─────────────────┘    └─────────────────┘    └─────────────────┘

Data Structures

Command Structure

typedef struct s_command {
    int is_correct;        // Validation flag
    char **args;           // Command arguments
    char *cmd_cpt;         // Command name
    char *path;            // Command path
    char *inredir;         // Input redirection
    char **delimiters;     // Here-doc delimiters
    char **outredirs;      // Output redirections
    int appd_out;          // Append flag
    int error;             // Error status
} t_command;

Environment List

typedef struct s_list_envp {
    char *envp_content;           // Environment variable
    struct s_list_envp *next;     // Next node
} t_list_env;

📁 Project Structure

Babuterm/
├── 📄 Makefile              # Build configuration
├── 📄 minishell.h           # Main header file
├── 📄 structs.h             # Data structures
├── 📁 src/                  # Source code
│   ├── 📄 main.c            # Entry point
│   ├── 📄 minishell.c       # Core shell logic
│   ├── 📁 builtin/          # Built-in commands
│   │   ├── 📄 ft_echo.c     # Echo implementation
│   │   ├── 📄 ft_cd.c       # CD implementation
│   │   ├── 📄 ft_export.c   # Export implementation
│   │   └── 📄 ...           # Other built-ins
│   ├── 📁 parsing/          # Input parsing
│   │   ├── 📄 parse_commands.c
│   │   └── 📄 ...
│   ├── 📁 commands/         # Command execution
│   ├── 📁 redirection/      # I/O redirection
│   ├── 📁 signals/          # Signal handling
│   ├── 📁 utils/            # Utility functions
│   └── 📁 errors/           # Error handling
├── 📁 libft/                # Custom C library
│   ├── 📄 libft.h
│   ├── 📄 ft_*.c            # Library functions
│   └── 📁 get_next_line/    # GNL implementation
└── 📁 obj/                  # Compiled objects

🧠 Memory Management

Safe Memory Practices

• Automatic Cleanup: All allocated memory is properly freed
• Error Handling: Memory cleanup on all error paths
• Leak Prevention: Comprehensive testing for memory leaks
• Resource Management: Proper file descriptor and process cleanup

Memory Testing

# Test for memory leaks
valgrind --leak-check=full --track-origins=yes ./minishell

# Test with specific commands
echo "command" | valgrind ./minishell

📡 Signal Handling

Interactive Mode

• SIGINT (Ctrl+C): Display new prompt
• SIGQUIT (Ctrl+\): Ignored
• EOF (Ctrl+D): Exit shell

Command Execution

• SIGINT: Interrupt running command
• SIGQUIT: Send quit signal to command
• Child Processes: Proper signal propagation

🧪 Testing

Manual Testing

# Basic functionality
echo "test" | ./minishell
echo "ls | wc -l" | ./minishell
echo "export TEST=value && echo \$TEST" | ./minishell

# Edge cases
echo "ls |" | ./minishell           # Syntax error
echo "echo \"unclosed quote" | ./minishell  # Quote error

Automated Testing

# Create test suite
bash test_suite.sh

# Compare with bash
echo "command" | bash > expected.txt
echo "command" | ./minishell > result.txt
diff expected.txt result.txt

👥 Authors

Author	GitHub	Email
manufern	@manufern	manufern@student.42.fr
cfeliz-r	@cfeliz-r	cfeliz-r@student.42.fr

📊 Project Statistics

• Lines of Code: ~2,750
• Files: 45+ source files
• Functions: 100+ custom functions
• Development Time: 3+ months
• Language: C (C99 standard)

🤝 Contributing

While this is an educational project, contributions and suggestions are welcome:

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 part of the 42 School curriculum. It's shared for educational purposes.

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Made with ❤️ at 42 Madrid

"The shell is the ultimate power tool"