Adding a Function

Hi, I've been using PHP for several years and I take is as my primary priority for making web applications. But recently I'm having a problem in file reading. I have a huge file containing simple text data. Whatever I append to the file it adds at the bottom, It's OK but, I want to read the file from the bottom by lines and I couldn't find any appropriate function to do this, and as It's a huge file (50mb+) it takes forever to load by the formal way from the start. So I'm requesting PHP crew to add a function that can read files backwards from the end by lines. It'll be a huge help for me including many programmers :-) THANK YOU