How to rename an uploaded file to give it a unique name with PHP
If you own an interactive website where your users can upload their files, you will need to insure that each file has a unique name that can be used as an identifier. One way to accomplish this task is to add a timestamp to the filename. Granted two users could upload a file with exactly the same name at exactly the same time. But unless you have a website with billions of visitors per day you should be safe.
As you could probably guess the function to change a file's name goes under the name of rename(). The other function that we will use in the following example is file_exists(), simply to check if the file and path specified are indeed correct.
$tmp_name = "file.txt";
$new_name = "file".time().".txt";
echo "<i>".$tmp_name."</i> has been renamed to: <i>".$new_name."</i>";
echo "The file <i>".$tmp_name."</i> could not be found.";