Recent ImageMagick update kicked a little in the nuts. I mainly convert PDF to PNG and then use them for OCR. Here is how it welcomed me after an update to 6.7.2:
sh: gs: command not found
convert: missing an image filename
It works ok from a command line, but fails from Java or any external environments. At first the error may look like a command line syntax change, but it isnt, dont start moving your flags places or in-front/after PDF file - this is not the problem here.
SOLUTION
1) # which gs
2) locate delegates.xml file in your system
3) open the file for editing (# nano /etc/ImageMagick/delegates.xml)
4) find all occurrences of "gs", which will be simply put in html quotes: <...>command=""gs" -q <..> and replace it with the output of you "which gs" result, in my case it looked like this: <..>command=""/usr/local/bin/gs" -q <..>. Leave the surrounding syntax intact.
After that just save the file and run you external command again. There will be around 10 occurrences, replace them all to be on the safe side, I suspect that its only PS configurations that had to be changed.
