Unix uses line feed ^J, Windows carriage return ^M for carriage control. Files from Windows can be converted using dos2unix or unix2dos (on most unix systems) when transferring in reverse. ascii mode ftp will also perform carriage control translation implicitly.

Without any such translation, unix, when seeing both characters will pick the LF as the carriage control and render the ^M separately. Some unix programs can interpret a single ^M as carriage control but the addition of "\n" (^J on unix) will force it to pick only the ^J for carriage control and to render the ^M.