Got HTTP status 404 Not Found for "http://roaringjelly.org/~jc/music/book/CR/JohnWalsh.abc"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-8421-JohnWalsh.ps) >>/Users/jc/w/tmp/Tune-8421-get.log 2>&1" returned status 256
http://roaringjelly.org/~jc/music/book/CR/JohnWalsh.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-8421-JohnWalsh.abc 144 ABC music file with the extracted tune(s)
Tune-8421-JohnWalsh.ps 6 PostScript
Tune-8421-JohnWalsh.txt 144 Plain-text file with the extracted tune(s)
Tune-8421-get.log 4033 Log file, useful mostly for debugging
Tune-84216-get.log 1489 Log file, useful mostly for debugging
These files should be available for 24 hours.