hosts - /etc/hosts Manager

A modern Python TUI (Text User Interface) application for managing your system's /etc/hosts file with ease and safety.

Overview

The hosts application provides a powerful, user-friendly terminal interface for viewing, editing, and managing your /etc/hosts file. It eliminates the need for manual text editing while providing advanced features like DNS resolution, entry validation, and comprehensive backup capabilities.

Features

🔍 Read-Only Mode (Default)

• Two-pane interface: List view with detailed entry information
• Smart parsing: Handles all real-world hosts file formats
• Sorting capabilities: Sort by IP address or hostname
• Filtering options: Hide/show system default entries
• Search functionality: Find entries by hostname, IP, or comment
• Configuration management: Persistent settings with modal interface
• Live reload: Automatically refresh when hosts file changes

✏️ Edit Mode (Permission-Protected)

• Safe editing: Automatic backups before any modifications
• Entry management: Add, delete, and modify host entries
• Activation control: Toggle entries active/inactive
• Reordering: Move entries up/down with keyboard shortcuts
• Undo/Redo system: Full operation history with Ctrl+Z/Ctrl+Y
• Atomic operations: Safe file writing with rollback capability
• Permission management: Secure sudo handling for system file access

🛡️ Safety & Reliability

• Automatic backups: Timestamped backups before modifications
• Change detection: Track modifications with save confirmation
• Input validation: Comprehensive IP and hostname validation
• Error handling: Graceful error recovery with user feedback
• File integrity: Preserve comments and formatting

Installation

Prerequisites

• Python 3.13 or higher
• uv package manager

Run with uv

uvx git+https://git.s1q.dev/phg/hosts.git

Setup alias

# Install uv if not already installed
echo "alias hosts=\"uvx git+https://git.s1q.dev/phg/hosts.git\"" >> ~/.zshrc

Usage

Basic Usage

# Launch the application
uv run hosts

# Or if installed globally
hosts

Interface Overview

Keyboard Shortcuts

Navigation

• ↑/↓: Navigate entries
• Home/End: Go to first/last entry
• Page Up/Down: Navigate by page

View Operations

• Ctrl+e: Toggle between Read-only and Edit mode
• Ctrl+r: Reload hosts file
• i: Sort by IP address
• h: Sort by hostname
• c: Open configuration modal
• q or Ctrl+C: Quit application

Edit Mode (requires sudo)

• e: Toggle Entry edit mode
• Space: Toggle entry active/inactive
• Shift+↑/↓: Move entry up/down
• n: Add new entry
• d: Delete selected entry
• r: Update the current select DNS based Entry
• Shift+r: Update all DNS based Entries
• Ctrl+z: Undo last operation
• Ctrl+y: Redo operation
• Ctrl+s: Save changes

Configuration

The application stores its configuration in ~/.config/hosts-manager/config.json:

{
  "show_default_entries": true,
  "default_sort_column": "ip",
  "default_sort_reverse": false,
  "backup_directory": "~/.config/hosts-manager/backups"
}

Configuration Options

• show_default_entries: Show/hide system default entries (localhost, etc.)
• default_sort_column: Default sorting column ("ip" or "hostname")
• default_sort_reverse: Default sort direction
• backup_directory: Location for automatic backups

Architecture

The application follows a clean, layered architecture:

src/hosts/
├── main.py              # Application entry point
├── core/                # Business logic layer
│   ├── models.py        # Data models (HostEntry, HostsFile)
│   ├── parser.py        # File parsing and writing
│   ├── manager.py       # Edit operations and permissions
│   ├── config.py        # Configuration management
│   ├── dns.py           # DNS resolution (planned)
│   ├── commands.py      # Command pattern for undo/redo
│   ├── filters.py       # Entry filtering and search
│   └── import_export.py # Data import/export utilities
└── tui/                 # User interface layer
    ├── app.py           # Main TUI application
    ├── styles.py        # Visual styling
    ├── keybindings.py   # Keyboard shortcuts
    └── *.py             # Modal dialogs and components

Key Components

• HostEntry: Immutable data class representing a single hosts entry
• HostsFile: Container managing collections of entries with operations
• HostsParser: File I/O operations with atomic writing and backup
• HostsManager: Edit mode operations with permission management
• HostsManagerApp: Main TUI application with Textual framework

Development

Setup Development Environment

# Clone and enter directory
git clone https://github.com/yourusername/hosts.git
cd hosts

# Install development dependencies
uv sync

# Run tests
uv run pytest

# Run linting
uv run ruff check
uv run ruff format

Testing

The project maintains comprehensive test coverage with 150+ tests:

# Run all tests
uv run pytest

# Run specific test modules
uv run pytest tests/test_models.py
uv run pytest tests/test_parser.py

# Run with coverage
uv run pytest --cov=src/hosts

Test Coverage

• Models: Data validation and serialization (27 tests)
• Parser: File operations and parsing (15 tests)
• Manager: Edit operations and permissions (38 tests)
• Configuration: Settings persistence (22 tests)
• TUI Components: User interface (28 tests)
• Commands: Undo/redo system (43 tests)
• Integration: End-to-end workflows (additional tests)

Code Quality

The project uses ruff for linting and formatting:

# Check code quality
uv run ruff check

# Format code
uv run ruff format

# Fix auto-fixable issues
uv run ruff check --fix

Security Considerations

• Sudo handling: Secure elevation only when entering edit mode
• File validation: Comprehensive input validation and sanitization
• Atomic operations: Safe file writing to prevent corruption
• Backup system: Automatic backups before any modifications
• Permission boundaries: Clear separation between read and edit operations

Troubleshooting

Common Issues

Permission denied when entering edit mode:

# Ensure you can run sudo
sudo -v

# Check file permissions
ls -la /etc/hosts

Configuration not saving:

# Ensure config directory exists
mkdir -p ~/.config/hosts-manager

# Check directory permissions
ls -la ~/.config/

Application won't start:

# Check Python version
python3 --version

# Verify uv installation
uv --version

# Install dependencies
uv sync

Contributing

We welcome contributions! Please see our development setup above.

Contribution Guidelines

1. Fork the repository and create a feature branch
2. Write tests for new functionality
3. Ensure all tests pass with uv run pytest
4. Follow code style with uv run ruff check
5. Submit a pull request with clear description

Future Enhancements

• DNS Resolution: Automatic hostname-to-IP resolution
• Import/Export: Support for different file formats
• Advanced Filtering: Complex search and filter capabilities
• Performance Optimization: Large file handling improvements

License

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

Support

• Issues: Report bugs and feature requests on GitHub Issues
• Documentation: See the project wiki
• Discussions: Join community discussions on GitHub Discussions

---

Note: This application modifies system files. Always ensure you have proper backups and understand the implications of hosts file changes. The application includes safety features, but system administration knowledge is recommended.