while (!feof($fp)) {
         
        $line =  fgets($fp, 128);
        echo $line."\n";
        
        $line = explode(":soda", $line);
        
        echo $line[0]."\n";

        if ($line[1]) {
            
            fwrite($fp, "pop".$line[1]."\r\n"); 
        }

    }
    
    fclose($fp);