vignette problem

Dear R People:

I'm using R-2.8.1 on Ubuntu Jaunty jackalope (or whatever its name
is), and having a problem with the vignette function:

vignette("snowfall")

sh: /usr/bin/xpdf: not found

Has anyone run into this, please?
Or is this for the Debian R list, please?

Thanks,
Erin

Erin Hodgess
Associate Professor
Department of Computer and Mathematical Sciences
University of Houston - Downtown
mailto: erinm.hodgess at gmail.com