How to Sync Two Folders in Python (Lightweight Backup)

import os
import shutil
import sys
from pathlib import Path

def sync_folders(src: Path, dst: Path):
    """Sync src folder to dst folder, copying missing/updated files."""
    dst.mkdir(parents=True, exist_ok=True)

    for src_path in src.rglob("*"):
        relative = src_path.relative_to(src)
        dst_path = dst / relative

        if src_path.is_dir():
            dst_path.mkdir(parents=True, exist_ok=True)
        elif src_path.is_file():
            if not dst_path.exists() or src_path.stat().st_mtime > dst_path.stat().st_mtime:
                shutil.copy2(src_path, dst_path)
                print(f"Copied: {relative}")

    # Remove files in dst not present in src
    for dst_path in dst.rglob("*"):
        relative = dst_path.relative_to(dst)
        src_path = src / relative
        if not src_path.exists():
            if dst_path.is_dir():
                shutil.rmtree(dst_path)
            else:
                dst_path.unlink()
            print(f"Removed: {relative}")

if __name__ == "__main__":
    if len(sys.argv) != 3:
        print("Usage: python sync_folders.py <source> <destination>")
        sys.exit(1)
    source = Path(sys.argv[1])
    destination = Path(sys.argv[2])
    if not source.is_dir():
        print("Source must be an existing directory.")
        sys.exit(1)
    sync_folders(source, destination)