Generating .jpg .pdf files and so forth

[rubyFeedback]

Is it possible to generate .jpg and .pdf files, via the commandline?

This would be quite interesting, kind of a "live .pdf builder" or so,
a bit like the programming language R is used to render a plot,
which is then used in e. g. a statistics paper. Would be cool if
flammarion can also cover that use case.