I have used this a bit to see what’s going on with Apache, when something goes wrong. If, while at your trusty Ubuntu command line, you type ‘tail -F’ and then a file name, it will sit there and show you additions to the file as they occur. This means that you could type ‘sudo tail -F /var/log/apache2/error.log’ and it will sit there and spit out Apache2 error messages as they occur. Good for figuring out what you broke today. 🙂