Output HTML to a file

Hello list, I need to capture, into a file, the HTML generated via my PHP. I just wanted to verify there was not an easy solution that would allow me to redirect my output to a file (since I have the PHP page generating the HTML and currently displaying to the browser). I have read the list about the setting everything into a string, then fwriting the string. Just wanted to check before I go to the trouble of modifying every line in my PHP page. Thanks a head of time, Kevin