I was just browsing around in the LSR and found this very useful bit
that is just fantastic, I hadn't come across it in any docs - LM, NR, or
IR (I did a browser Edit/Find for output-suffix on all of those) -
#(define output-suffix "you-put-something-here")
It's for use in a multi-bookpart .ly file that generates multiple .pdf
files. Typically the file names are appended with -1, -2, -3, etc which
isn't very helpful. That little bit of code lets you append any bit of
text to the file name, so instead of
filename-1.pdf
you get
filename-you-put-something-here-1.pdf