back-up files

Hi, I'm trying to figure out a way to run a back-up of a directory that has more directories and regular files in it. This is easy with the copy function, but what I can't figure out is how to do back-ups (copy) after the first, so new made files can be backed up without having to make multiple copies of the same original directory with a different name.

I found this at php.net that copies all files and directories.--------------------

  function my_copy($oldname, $newname)
  {
   if(is_file($oldname)){
     $perms = fileperms($oldname);
     return copy($oldname, $newname) && chmod($newname, $perms);
   }
   else if(is_dir($oldname)){
     my_dir_copy($oldname, $newname);
   }
   else{
     die("Cannot copy file: $oldname (it's neither a file nor a directory)");
   }
  }
     
  function my_dir_copy($oldname, $newname)
  {
   if(!is_dir($newname)){
     mkdir($newname);
   }
   $dir = opendir($oldname);
   while($file = readdir($dir)){
     if($file == "." || $file == ".."){
       continue;
     }
     my_copy("$oldname/$file", "$newname/$file");
   }
   closedir($dir);
  }
-----------------------
But I don't understand the function attribute, I'm used to saying something like:

if ($action=="this")
{
 run code here
}

Thanks
LVL 1
dsynAsked:
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dsynAuthor Commented:
point increase
ashooooCommented:
I dont understand  your question very well...

Do you mean you dont understant the format of the if() statement?

If thats your question, the if() statement checks to see if the expression evaluates to true. If you use the == operator, it either returns a true of a false. If you use any other expression, for example a function, its return value is used by the if statement.

for example.. if(foo()) will check for the return value of foo().

If your question is something else, please explain and I'll try to help.
dsynAuthor Commented:
I want to back up a directory and everything inside it into another directory. After the initial back-up I want to be able to add new files without having to back-up files that have already been backed up.

Thanks.
ashooooCommented:
I dont know about linux... but in windows, you can check for the 'archive' attribute. If its set, you need to back up the file and reset this attribute. If its not set, it means that the file is not modified.

Hope this helps
aolXFTCommented:
Hmmm,

This sounds kinda like rsync

Check the last modified time of the archive, using filemtime();

Go through the directory you want to back up using the directory functions.

Test each file using filemtime(), and if it is newer than the archive then back it up

otherwise skip on to the next file.

I would suggest you do this with a recursive algorithm.

PS by the word 'archive' I mean back up directory.

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