string replace in files

I am trying to write a script that will replace a string in a file. Actually, about 3000 files. And I am stuck. I can get the list of files, but then I pretty much become stuck. I wanted to try str_ireplace (not sure if that is what I should use or not), but I can't even get far enough to do that. I am hoping that someone out there has an easy response to this. Below is the code that I have so far. Thanks Steve #!/usr/bin/php <? $strtoreplace="require \"http://www.domain.com/"; $replacewithstring="require \"/home/domain/www/"; replacestring(); function replacestring(){ GLOBAL $strtoreplace,$replacewithstring;

        $FILES=array(ls -1 */*|grep .php);
        foreach($FILES as $value){
                if($value){
                        echo "file $value\n";
                        $handle=fopen($value,'a');
                }
        }

} ?>