I use Filezilla to do my FTP duties and I'm unable to copy files without making a copy to the my local computer.
I doubt Filezilla is bad software. Is this just an inherent quality of FTP?
The FTP Protocol does not define a "copy" command.
If your FTP client has a copy command, then it has to implement this itself using what's available through FTP. This works out to something like: GET/RETR , CWD , PUT/STOR .
Some FTP servers will implement proprietary extensions and offer a command like COPY. A client may or may not choose to implement these, in which case it doesn't involve a local file copy.
According to the error messages I get within WinSCP when I try and duplicate or copy.. apparently it is.
I'm guessing there's some FTP theory on it somewhere. Even to duplicate WinSCP wanted to temp dump stuff to my local machine.
There aren't any copy commands listed at the list of FTP commands, so it's not in the FTP definition. It's just something FTP clients add themselves to be more user-friendly.
来源：https://stackoverflow.com/questions/1123229/copying-files-to-a-remote-server-over-ftp-protocol