pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-29039-172.ps) >>/Users/jc/w/tmp/Tune-29039-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/abc/mirror/www.leeds.ac.uk/petrie/abc/172.abc

Error exit status 256; here are some files to check:
[P=get.cgi V=1/1 B=0 scale=0.60 512x512 PNG]
filesizedescription
Tune-29039-172.abc 81 ABC music file with the extracted tune(s)
Tune-29039-172.ps 31263 PostScript
Tune-29039-172.txt 81 Plain-text file with the extracted tune(s)
Tune-29039-get.log 4337 Log file, useful mostly for debugging
These files should be available for 24 hours.