Batch editing files.

[Boogityboo04]

I have about 300 php files that I need to insert a header into the top of. Does anyone one know of a program or script to loop through all the files in a directory with a certain extension and add something into them? I also need to search through them and find and replace all intances of several keywords.

Is there any way to do this?

EDIT: It looks like I found the answer. I was playing around in Notepad++ and just tried opening all 398 files at once and running a find and replace on all open files.