Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/abc2/cont.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-9776-cont.ps) >>/Users/jc/w/tmp/Tune-9776-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/abc2/cont.abc

Error exit status 256; here are some files to check:
[P=tuneget V=1/1 B=0 scale=0.70 512x512 PNG]
filesizedescription
Tune-9776-cont.abc 141 ABC music file with the extracted tune(s)
Tune-9776-cont.ps 6 PostScript
Tune-9776-cont.txt 141 Plain-text file with the extracted tune(s)
Tune-9776-get.log 9472 Log file, useful mostly for debugging
Tune-97762-get.log 5686 Log file, useful mostly for debugging
Tune-97765-get.log 3743 Log file, useful mostly for debugging
Tune-97767-Kerr_MM4-V1.abc 148 ABC music file with the extracted tune(s)
Tune-97767-Kerr_MM4-V1.ps 6 PostScript
Tune-97767-Kerr_MM4-V1.txt 148 Plain-text file with the extracted tune(s)
Tune-97767-get.log 4133 Log file, useful mostly for debugging
Tune-97769-get.log 3474 Log file, useful mostly for debugging
These files should be available for 24 hours.