With the concept of tail -f, only the script was provided, where you have the list updated in the file 'update' every 'n' seconds maintained in the for loop, if you want to refresh the list as soon as possible, decrement the sleep time.

Though I had not done extensive testing for the posted script. I just verified whether the update file is getting refreshed and it worked for me.

Am sure the required difference would be necessarily be captured.

Please post us with what is needed and whats happening!