Lilypond command line syntax

[Phil Holmes]

I've got my shell-based Ubuntu regtest comparator working well, using 
comparison functions from imagemagick.  What I want to do now is make it use 
more CPUs by using job-count.  AFAIK, this works by processing multiple 
files in parallel, rather than using lots of CPUs for a single file.  The 
simplest way to pass lots of filenames to lily is a ls > dir.txt and 
then -dread-file-list="dir.txt".  However, if I do this, fails to find an 
include file, which is important to get rid of the tagline.  If I try 
running it from a lower level directory and use the -o flag to put the 
output files in the correct output directory, it puts the first one in the 
right place and then either names the others DirName.png or simply doesn't 
output them.  Here's a synopsis of what I want.

We're in dir Test.
Get a list of all lilypond files that are currently in Test/input
Use that list of files to run lilypond, with all output PNGs going to 
Test/Pix and including file Test/include.ly.  The .png files should use the 
root filename of each .ly file processed.

Sounds easy, but I couldn't get it to work.  If a determined command-line 
hacker could try to provide the right syntax, I would be very grateful.

--
Phil Holmes