寻找一种自动检查文件更新的方法，如果有更改，请下载到我们服务器上的目录

We will be implementing a new template for our web site. The template actually lives on another server. I would like to schedule a script to run nightly, to check if the remote page has been updated since the last download, and if so, download the file to a directory on our server. I can use either perl or php.

In nothing but PHP, you could use something like similar_text() (or levenshtein() ):

if(similar_text( // line breaks for clarity.
    file_get_contents("/path/to/local.tpl"), 
    file_get_contents("http://remote.com/remote.tpl") < 90
 ) {// thus, if the similarity between the two files is less than 90%, 
     file_put_contents("/path/to/local.tpl", "http://remote.com/remote.tpl"); 
 }// download and save the remote template.

Or, if you wanted to use rsync - just go for system() or exec() and pass a script as the argument.

to make it run nightly, you just add it to the crontab:

crontab -e

add:

59 23 * * * /path/to/bash-or-php.script