Got HTTP status 404 Not Found for "http://john-chambers.us/~jc/music/book/JamesOswald/CPC/21250_.abc/all"
pngcmd="(./ps2png 512 512 /Users/jc/w/tmp/Tune-24911-all.ps) >>/Users/jc/w/tmp/Tune-24911-get.log 2>&1" returned status 256
http://john-chambers.us/~jc/music/book/JamesOswald/CPC/21250_.abc/all

Error exit status 256; here are some files to check:
[get.cgi V=1/1 B=0 scale=0.55 512x512 PNG]
filesizedescription
Tune-24911-1809_Cahusac_FTM-001.svg 118133 Scalable Vector Graphics format
Tune-24911-1809_Cahusac_FTM-002.svg 112259 Scalable Vector Graphics format
Tune-24911-1809_Cahusac_FTM-003.svg 121118 Scalable Vector Graphics format
Tune-24911-1809_Cahusac_FTM-004.svg 14139 Scalable Vector Graphics format
Tune-24911-1809_Cahusac_FTM.abc 12029 ABC music file with the extracted tune(s)
Tune-24911-1809_Cahusac_FTM.txt 12029 Plain-text file with the extracted tune(s)
Tune-24911-all.abc 158 ABC music file with the extracted tune(s)
Tune-24911-all.ps 6 PostScript
Tune-24911-all.txt 158 Plain-text file with the extracted tune(s)
Tune-24911-get.log 22940 Log file, useful mostly for debugging
These files should be available for 24 hours.