flutter cli: hot reload on file save

flutter-hot-reload

#!/bin/bash

# Flutter Hot Reload Script
# Usage: ./flutter-hot-reload.sh [-d device_id] [-w watch_dir]
# depends on fswatch

# Default values
DEVICE=""
WATCH_DIR="lib/"

# Parse command line arguments
while [[ $# -gt 0 ]]; do
    case $1 in
        -d|--device)
            DEVICE="$2"
            shift 2
            ;;
        -w|--watch)
            WATCH_DIR="$2"
            shift 2
            ;;
        -h|--help)
            echo "Usage: $0 [-d device_id] [-w watch_directory]"
            echo "  -d, --device    Device ID (e.g., emulator-5554)"
            echo "  -w, --watch     Directory to watch for changes (default: lib/)"
            echo "  -h, --help      Show this help message"
            exit 0
            ;;
        *)
            echo "Unknown option: $1"
            echo "Use -h for help"
            exit 1
            ;;
    esac
done

# Check if we're in a Flutter project
if [ ! -f "pubspec.yaml" ]; then
    echo "Error: Not in a Flutter project directory (no pubspec.yaml found)"
    exit 1
fi

# Check if watch directory exists
if [ ! -d "$WATCH_DIR" ]; then
    echo "Error: Watch directory '$WATCH_DIR' does not exist"
    exit 1
fi

# Build flutter run command
FLUTTER_CMD="flutter run"
if [ -n "$DEVICE" ]; then
    FLUTTER_CMD="$FLUTTER_CMD -d $DEVICE"
fi

echo "Starting Flutter with hot reload..."
echo "Device: ${DEVICE:-"default"}"
echo "Watching: $WATCH_DIR"
echo "Press Ctrl+C to stop"
echo

# Start flutter run in background
$FLUTTER_CMD &
FLUTTER_PID=$!

# Function to cleanup on exit
cleanup() {
    echo
    echo "Stopping Flutter..."
    kill $FLUTTER_PID 2>/dev/null
    exit 0
}

# Set up signal handlers
trap cleanup SIGINT SIGTERM

# Watch for file changes and send 'r' to flutter process
fswatch -o "$WATCH_DIR" | while read f; do
    echo "Files changed, hot reloading..."
    echo "r" > /proc/$FLUTTER_PID/fd/0 2>/dev/null || {
        # If /proc method fails, try alternative approach
        kill -USR1 $FLUTTER_PID 2>/dev/null
    }
done