def touch(file_path):
    """
    Emulates the Linux 'touch' command by creating an empty file if it doesn't exist, or updating the modified timestamp if it does.

    :param file_path: str: The path to the file to be created or updated.
    :return: None
    """
    if not os.path.exists(file_path):
        p = Path(file_path)
        # ensure parent directory exists
        os.makedirs(str(p.parent), exist_ok=True)
        open(file_path, "w").close()

    # Update the modified timestamp
    os.utime(file_path)

    Emulates the Linux 'touch' command by creating an empty file if it doesn't exist, or updating the modified timestamp if it does.

    :param file_path: str: The path to the file to be created or updated.
    :return: None
    
python/aitemplate/utils/io.py