Linux Tips: Using ‘tail’ to Display File Updates in Realtime

This article will show you how to use the tail command to automatically view data that is appended to a file. This is particularly useful when you want to view the progress of some process from a log file. For example, if you want to see when the Apache server has finished loading, instead of doing a cat on the log file every few seconds you can use the tail command to constantly monitor the log file and output any updates to it.

Using tail to follow a file

To display data that is being appended to a file
tail -f [filename]

Now whenever new data is appended into the file specific, it will be displayed!

One convenient option to use is the -n flag which specifies how many lines of the file to display before it begins following. For example:
tail -f [filename] -n 500

This will output the last 500 files of the file and then begin following it for changes.