When scripting in bash or any other shell in *NIX, while running a command that will take more than a few seconds, a progress bar is needed. For example, copying a big file, opening a big tar file. What ways do you recommend to add progress bars to shell scripts?
![How to add a progress bar to a shell script?](https://cdn-ak-scissors.b.st-hatena.com/image/square/98d6f053a97a87156775f60757c60865d0f2c47d/height=288;version=1;width=512/https%3A%2F%2Fcdn.sstatic.net%2FSites%2Fstackoverflow%2FImg%2Fapple-touch-icon%402.png%3Fv%3D73d79a89bded)