pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-17807-Niel_Gow.ps) >>/Users/jc/w/tmp/Tune-17807-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/abc/by/Niel_Gow.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-17807-Niel_Gow.abc 38244 ABC music file with the extracted tune(s)
Tune-17807-Niel_Gow.ps 411399 PostScript
Tune-17807-Niel_Gow.txt 38244 Plain-text file with the extracted tune(s)
Tune-17807-get.log 48468 Log file, useful mostly for debugging
These files should be available for 24 hours.