[PD] Running external software from within a Pd external

[Jaime E Oliver via Pd-list]

Hi, 

I am trying to figure out how to call and run an external software from within a Pure Data external.

The specific case is that I have an external generating Lilypond scores, but I'd like the external to go further and open this score with the Lilypond software[1], compile the score and produce a pdf or ps document. All from within the same command in Pd. 

Any pointers?

J

[1] lilypond.org