我可以使用PHP / Perl脚本在所有PHP文件的末尾添加一些文本/代码吗？

I need to rescript every file on my website by putting a footer at the bottom.

Give this a try:

This will add the line $footer_code to the end of all php files in $dir.

<?php

  $dir = 'YOUR DIRECTORY';
  $footer_code = "footer code";

  if ($handle = opendir($dir)) {
    while (false !== ($file = readdir($handle))) {
        if (substr($file, -4) == '.php') {
          $fh = fopen($file, 'a') or die("can't open file");
          fwrite($fh, $footer_code);
          fclose($fh);
        }
    }
    closedir($handle);
  }

?>

There is an Apache module lets you set a common footer for every file served, check this for mroe -> http://freshmeat.net/projects/mod_layout/

If this is some boilerplate code that all of your pages need, then might I suggest using some sort of abstract class that all of the actual pages in your website extend. This way all of the common code can be kept in one file and you don't have to worry about separately updating every single one of your pages every time you have an update for the common code.

<?php
    abstract class AbstractPage {
        // Constructor that children can call 
        protected function __construct() {
        }

        // Other functions that may be common
        private function displayHeader() {}
        private function displaySidebar() {}
        private function displayFooter() {}
        abstract protected function displayUniquePageInfo();

        public function display() {
            $this->displayHeader();
            $this->displaySidebar();
            $this->displayUniquePageInfo();
            $this->displayFooter();
        }

    }

    // Next have a page that inherits from AbstractPage
    public class ActualPage extends AbstractPage {
        public function __construct() {
            parent::__construct();
        }

        // Override function that displays each page's different info
        protected function displayUniquePageInfo() {
            // code
        }
    }

    // Actually display the webpage
    $page = new ActualPage();
    $page->display();
?>