Converting .lyx to .ps

[Ryan Wahle]

How can I convert .lyx to .ps ??  I can do it from LyX, but I need to do
it automatically from another program. I don't know what utility to use. I
have tried serveral like latex but they give me an error for some reason..
Can someone give me the commands that LyX does to convert to a .ps file
from the .lyx file?