CPW - Copy on Write

A CLI tool that watches for changes in files or directories and copies the changed files to a target destination.

Features

• Watch a single file or directory for changes
• Automatically copy changed files to the target destination
• Preserve directory structure when copying from a directory to another
• Initial copy of all files when watching directories
• Auto-create destination directories as needed
• Built-in versioning support

Installation

Using Homebrew

The easiest way to install CPW on macOS or Linux is via Homebrew:

# Add the tap
brew tap mxvsh/cpw

# Install CPW
brew install cpw

From Releases

You can download pre-built binaries for ARM64 and ARM architectures from the GitHub Releases page.

Available platforms:

• Linux ARM64 (aarch64)
• Linux ARM (armv7)
• macOS ARM64 (Apple Silicon)

From Source

# Clone the repository
git clone https://github.com/mxvsh/cpw.git
cd cpw

# Build the binary
make build

# Or build with a specific version
make build VERSION=v1.0.0

# Optionally move to a directory in your PATH
cp cpw /usr/local/bin/

Usage

# Basic usage
cpw <source> <destination>

# Check version
cpw -version

Examples

Watch a single file and copy it when changed:

cpw /path/to/source/file.txt /path/to/destination/file.txt

Watch a directory and copy any changed files with the same directory structure:

cpw /path/to/source/dir /path/to/destination/dir

How It Works

1. The program starts by checking if both source and destination locations exist
2. If watching a directory, it initially copies all files to the destination
3. The program then monitors the source for file changes (write or create events)
4. When a change is detected, the file is copied to the destination, preserving directory structure
5. If new directories are created, they are automatically added to the watch list

Versioning

CPW includes built-in versioning that displays:

• Version number (from Git tag)
• Commit SHA
• Build date

This information is automatically included in builds when:

• Building with make build VERSION=v1.0.0
• Creating a release with GitHub Actions

You can view the version information by running:

cpw -version

CI/CD

This project uses GitHub Actions to automatically build and release binaries for different architectures:

• When a tag is pushed with the format v* (e.g., v1.0.0), GitHub Actions will:
  • Build binaries for ARM64 and ARM architectures
  • Include version information in the builds
  • Create a GitHub release with these binaries
  • Generate release notes
  • Update the Homebrew formula

Dependencies

• github.com/fsnotify/fsnotify - File system notifications for Go