Ensures that line has a control return / line feed (CRLF) and
writes it to the socket.
# File lib/net/ftp.rb, line 418
def putline(line) # :nodoc:
if @debug_mode
print "put: ", sanitize(line), "\n"
end
if /[\r\n]/ =~ line
raise ArgumentError, "A line must not contain CR or LF"
end
line = line + CRLF
@sock.write(line)
end