What is this line: Ôªø and how to avoid it?

Question

Somehow I managed to insert Ôªø at the top of the PHP script. What is this terrifying group of characters, how could I get into it, and how can I expose and / or avoid it in the future?

Anecdotally, he was hiding at the very top of the PHP script, before <?php. The script needs to send a Content-type header. As Ôªø pushed the header from the top of the file, the server continued to send its own header, and it was 2 hours of fun. I have not even seen a line in nano or bash. But I redirected diff and there it was.

Answer 1

UTF-8 ( EF BB BF). , , , .

Answer 2

, , . , script , . , , . , .