🐚 PyShell — A Feature-Rich POSIX-Compatible Shell in Python

A feature-rich, POSIX-compatible shell implemented in Python with advanced scripting capabilities.
Cross-platform and extensible, PyShell brings the power of Unix-style scripting to Python environments.

✨ Features

• POSIX Compatibility: Standard shell syntax (if, while, for, case)
• Advanced Arrays: Indexed and associative arrays
• Pipeline Support: Full pipe, redirection, and background job control
• Function Definitions: Shell functions with local variables
• Parameter Expansion: ${var:-default}, ${var#pattern}, etc.
• Command Substitution: $(command) and backtick syntax
• Arithmetic Expansion: $((expression)) with full math operations
• Brace Expansion: {1..10}, {a,b,c}
• Glob Patterns: *, ?, [...] with extended matching
• Built-in Commands: 50+ built-ins (cd, echo, export, test, local, etc.)
• Job Control: Background jobs with fg / bg
• History & Completion: Command history with readline integration
• Aliases: Command aliasing support
• Cross-Platform: Works on Linux, macOS, and Windows

🚀 Installation

<<<<<<< HEAD

From Source

git clone https://github.com/yogvidwankhede/PyShell.git
cd pyshell
pip install -e .

Using pip (once published)

=======

pip install pyshell-terminal

From Source

git clone https://github.com/yogvidwankhede/PyShell.git
cd PyShell
pip install -e .

📖 Usage

Interactive Mode

python main.py

Execute Command

python main.py -c "echo Hello World"

Run Script

python main.py script.sh

💡 Examples

Variables and Arrays

# Simple variables
name="PyShell"
echo $name

# Arrays
arr=(one two three)
echo ${arr[0]}
echo ${arr[@]}

# Associative arrays
declare -A config
config[host]="localhost"
config[port]=8080
echo ${config[host]}

Control Flow

# If statements
if [ -f "file.txt" ]; then
    echo "File exists"
else
    echo "File not found"
fi

# Loops
for i in {1..5}; do
    echo "Count: $i"
done

# While loops
count=0
while [ $count -lt 5 ]; do
    echo $count
    count=$((count + 1))
done

Functions

greet() {
    local name=$1
    echo "Hello, $name!"
}

greet "World"

Pipelines and Redirection

# Pipes
cat file.txt | grep "pattern" | wc -l

# Redirection
echo "data" > output.txt
cat input.txt >> output.txt
command 2> errors.log

🏗️ Architecture

pyshell/
├── main.py           # Entry point and REPL
├── pyshell/
│   ├── tokenizer.py  # Lexical analysis
│   ├── parser.py     # Syntax analysis
│   ├── executor.py   # Command execution
│   ├── expansions.py # Variable/command expansion
│   ├── builtins.py   # Built-in commands
│   ├── state.py      # Global shell state
│   ├── ast_nodes.py  # AST node definitions
│   ├── exceptions.py # Custom exceptions
│   └── utils.py      # Utilities
└── tests/            # Test suite

🧪 Testing

python tests/run_all_tests.py

🤝 Contributing

Contributions are welcome! 🙌

1. Fork the repository
2. Create a feature branch

   git checkout -b feature/AmazingFeature
   

3. Commit your changes

   git commit -m "Add some AmazingFeature"
   

4. Push to your branch

   git push origin feature/AmazingFeature
   

5. Open a Pull Request

📝 Roadmap

• Tab completion improvements
• More POSIX test operators
• Process substitution
• Co-processes
• Additional shell options
• Performance optimizations

🙏 Acknowledgments

• Inspired by Bash, Zsh, and other Unix shells
• Built using Python’s readline and subprocess modules