To abort a file transfer, use the terminal interrupt key (usually
C-c). Sending transfers will be immediately halted. Receiving
transfers will be halted by sending a FTP protocol ABOR command to the
remote server, and discarding any further data received. The speed at
which this is accomplished depends upon the remote server's support
for ABOR processing. If the remote server does not support the
ABOR command, an ‘ftp>’ prompt will not appear until the
remote server has completed sending the requested file.
The terminal interrupt key sequence will be ignored when ftp
has completed any local processing and is awaiting a reply from the
remote server. A long delay in this mode may result from the
ABOR processing described above, or from unexpected behavior by
the remote server, including violations of the FTP protocol. If the
delay results from unexpected remote server behavior, the local
ftp program must be killed by hand.