...> abort [<session #>]
Abort an FTP session. This command works only on ftp sessions to terminate a "ftp get", "ftp put", or "ftp dir", operation in progress. If issued without an argument, the current session is aborted. NOTES:
When receiving a file, abort simply resets the data connection; the next incoming data packet will generate a "tcp reset" action to clear the remote server.
When sending a file, abort sends a premature end-of-file.
In both cases abort will leave a partial copy of the file on the destination directory, which must be removed manually if it is unwanted.