(PHP 7 >= 7.2.0)
ftp_append — Append the contents of a file to another file on the FTP server
$ftp
   , string $remote_file
   , string $local_file
   [, int $mode = FTP_BINARY
  ] ) : bool
This function is currently not documented; only its argument list is available.
ftp
remote_file
local_file
mode
   Returns TRUE on success or FALSE on failure.