Forwarding stdout/stderr of a child process in batch mode

[Paul Pogonyshev]

Hi,

I'm using Emacs in batch mode. I need to invoke a child process that
is a longish operation (a few minutes). During this time, it writes to
its stdout, so user will see that it is working and what exactly is
being done. However, if I invoke it from Emacs (e.g. using
`call-process') I see no way of forwarding this output to the "real"
stdout. So, for a user this looks like the process (or batch Emacs on
top of it) is hung.

Am I missing a way to forward output?

Paul