pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-20821-016_Quick_Step.ps) >>/Users/jc/w/tmp/Tune-20821-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/Stewart/SCAJMR/016_Quick_Step.abc

Error exit status 256; here are some files to check:
[P=tuneget V=1/1 B=0 scale=0.55 512x512 PNG]
filesizedescription
Tune-20821-016_Quick_Step.abc 583 ABC music file with the extracted tune(s)
Tune-20821-016_Quick_Step.ps 35432 PostScript
Tune-20821-016_Quick_Step.txt 583 Plain-text file with the extracted tune(s)
Tune-20821-get.log 4574 Log file, useful mostly for debugging
These files should be available for 24 hours.