pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-37239-2Vproto.ps) >>/Users/jc/w/tmp/Tune-37239-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/Stewart/SCAJMR/2Vproto.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-37239-2Vproto.abc 658 ABC music file with the extracted tune(s)
Tune-37239-2Vproto.ps 30852 PostScript
Tune-37239-2Vproto.txt 658 Plain-text file with the extracted tune(s)
Tune-37239-get.log 4717 Log file, useful mostly for debugging
These files should be available for 24 hours.