On the Crash Course page you've made me double my understanding of
/batch/ system. When we used it years ago we meant as opposed to
interactive. You submitted your batch job with job control and all the
jobs got ran in batches with all the other jobs that were ready when the
operator got around to it or as the result of a certain time coming
around. We would have used lilypond in an interative system by typing
the command when we wanted it to run and having it run right then which
is what I think I do now. I never have to submit jobs for lilypond and
it runs interactively when I ask it to.