copy(
$_SERVER['SCRIPT_NAME'].'uploaded_files/file.txt',
$_SERVER['SCRIPT_NAME'].'../completed_files/file.txt');
perhaps? Maybe some other $_SERVER[] variable - the absolute path up to and including the admin directory, anyway. That's assuming you mean
files
|
+-admin
| |
| +-uploaded_files
|
+-completed_files
Rereading that, it looks like you could mean
|
+-files
| |
| +-admin
| |
| +-uploaded_files
|
+-completed_files
In which case an additonal .. in diego25's or my code would be in order.