how to produce graphics from cli
i have just installed sage to ubuntu 15.10, and have been following along the 'tour of sage' and have been trying to get graphics to be produced from different functions, for example
sage: show(plot(sin(x) + sin(1.6*x), 0, 40)) Launched png viewer for Graphics object consisting of 1 graphics primitive
but not png viewer was launched. am i missing something?