Ruby script for mac os, that backups minecraft save data wherever you want to put. Modify save_path wherever you like to save data. Default backup path is set Documents/backup direcotry.

backup.rb

require 'fileutils'

#path to your minecraft save data.Ordinary minecraft's save data is game_path directory, but if you change your minecraft data to another place, change the game_path.
game_path = "/Users/YOUR_ACCOUNT_NAME/Library/Application\ Support/minecraft/saves"
#path to your directory where you want to save your minecraft save data.
save_path = "/Users/YOUR_ACCOUNT_NAME/Documents/backup/"

#make a folder named as daytime by Time.now method and copy save data files in that folder.
FileUtils.cp_r(game_path, save_path + Time.now.to_s)