so while while I'm using SSH to connect my server the backspace shows me bad character.

The backspace is the one with question mark. The backspace itself works normally, but in the screen, it wasn't very neat to look stacking question mark.

This is the example. The square-bracketed question mark means backspace.

cat[?] output: ca: not found

cat[?][?] output: c:not found

cat[?][?][?] output: nothing, because it simple delete the 3 character. Please help. Thank you.