在unix下的用shell写的进度显示小程序，可以自己扩展功能-Under unix used in writing the progress of shell showed procedures, can extend the functionality

shell编程经典指南：共9章，shell扩展编程完全指南1-9，开发人员必备！-shell programming classic Guide: Chapter 9, shell extension programming complete guide to 1-9, the developer must have!

对后台实时监视发现文件状态的变化，可以进行参考扩展，实现想实现的功能(Real time monitoring of the background, the discovery of changes in file status, you can reference expansion, to achieve the desired function)