in a strange quirk of fate, I happen to be experiencing the same problem, in Re: commandline ftpssl client ... a Tk frontend with Perl. I can plainly see the xterm is receiving more debug info than my Tk::Text widget watching the SDTOUT. In my case I think there is a low level system distinction between the tty output and stdout.

So I think the problem comes down to finding a way of tying STDERR to STDOUT, within the code. Googling for perl tying stderr to stdout is giving me some ideas.

For instance read: the basics of STDERR redirection especially the 1 reply.