shell output immediately, not after closing an application

[PKHG]

Hello,
Some years ago, a was able to tell XEmacs to immediately put the
output of a programm running
in a shell (eshell) by adding somewhere something like -n or so ...
forgotten what exactly.

So afresh;
I want to run Blender.exe in a shell, works nice, but the output of
Blender into 'its' shell (what blender sends) is only seen if I kill
Blender. but I would like to see the output at once, without killing
Blender.

Who know what to put into custom.el or init.el which command?

Any help is welcome
Peter