Hi Hippo
Using the other solutions as per http://www.perlmonks.org/?node_id=1155885 7zip still won't output each line it's zipping in real time. It could be a limitation of 7zip and how it works. Browser suggests that 7zip sends status updates via STDERR you listed an example with STDERR which I did try briefly but couldn't get it to work correctly either, I'll revisit your example if it is correct that 7zip outputs in realtime via STDERR.
Cheers