Taking PHP executed scipt and writing to htm file

I have looked far and low. I am sure the answer is already out here, but dont know what search terms to be looking for.

I am trying to take the full html generated by one of my PHP scripts and write it to an htm file.

Should I capturing all the PHP output to a string and then write it at execution time of the script?

Or should I be opening and capturing the PHP generated html to a string from an external PHP script ala fread ()?

Thanks

the first method, can select what to fwrite

the second method, fwrite the whole site..

depend on what u want to copy...IMHO

fread() method works fine to read myfile.php (I get the entire code), but I want it to actually ready the execute PHP generated HTML.

Likewise I cannot read:

myfile.php?id=215

How do I read the final product generated by the script, myfile.php?