Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/slide/Straight_Skillern.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-8771-Straight_Skillern.ps) >>/Users/jc/w/tmp/Tune-8771-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/slide/Straight_Skillern.abc

Error exit status 256; here are some files to check:
[P=tuneget V=1/1 B=0 scale=0.70 512x512 PNG]
filesizedescription
Find_87710.log 1623 Log file, useful mostly for debugging
List87718.log 162 Log file, useful mostly for debugging
Tune-8771-Straight_Skillern.abc 155 ABC music file with the extracted tune(s)
Tune-8771-Straight_Skillern.ps 6 PostScript
Tune-8771-Straight_Skillern.txt 155 Plain-text file with the extracted tune(s)
Tune-8771-get.log 4221 Log file, useful mostly for debugging
Tune-87711-24CountryDances_1812_JGray.abc 163 ABC music file with the extracted tune(s)
Tune-87711-24CountryDances_1812_JGray.ps 6 PostScript
Tune-87711-24CountryDances_1812_JGray.txt 163 Plain-text file with the extracted tune(s)
Tune-87711-get.log 4448 Log file, useful mostly for debugging
These files should be available for 24 hours.