While rendering a scene from houdini (or just generating rib files) is there a way to specify the path where the shaders will be output? I can't seam to find where I can set this up. The same thing goes for mantra - it seams like everything is generated at the $HOME path (like texture conversion etc) Is there a way to setup paths for everything that is generated during rendering?

Not sure but I found this in hconfig:

HOUDINI_RIBSHADER_DIR
This variable specifies the directory where Houdini should put RenderMan
shaders compiled from VOP Networks. The default is $HOUDINI_TEMP_DIR.
Only the compiled shader is placed in this directory. The source code
for the shader is always put in $HOUDINI_TEMP_DIR.