.htaccess how to hide .php?

Question

htaccess

Help me please! There is a site where users can register. A link must be created for each user. For example: example.com/username123.gif . The username123.gif file is the test.php file. I need to do something in htaccess so that when I follow the link example.com/username123.gif, the test.php file works. The name of the file in the link may be different, depending on the user's login. It is also necessary that this file can accept GET. For example:
example.com/username123.gif?qwerty
I'm very bad at all of this. Help me please!

Answer 1

Roughly speaking, everything is simple:
RewriteEngine on
# if a directory or a file exists, use the request directly
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
# otherwise forward the request to test.php
RewriteRule . test.php