To run Yafray from the command line:
in the Yafray panel, make sure xml is checked. This option writes YBtest.xml in the path that you have specified in Blender file options.
start the render as you would normally. Once the render is under way, kill it. As far as I know, there is no way to export the xml without actually starting the render.
From the command line, type yafray (assuming it is in your path), then YBtest.xml.
I am on a Linux machine, so my command looks like:
Yafray will write YBtest.tga in the same location as the xml.
Just typing yafray at the command line gives the following info:
Starting YafRay …
Usage: yafray [options] <file to render>
-s Render using the specified strategy. Valid values are
“threaded”: Multi-threaded (default)
“mono”: Single process
-c N Number of threads/processes to use
-z Use Net optimized
-p <PATH> Specify alternative plugin path
-r min_x:max_x:min_y:max_y Render region, values between -1 and 1
whole image is -r -1:1:-1:1
-v YafRay Version
Best of Luck!