Well, the utility actually implies the presence of the bash shell on every platform different from Windows... Mac OS should not be a problem, but I cannot speak about Solaris...
I haven't checked throughly about zip command compatibility, because I assumed the options I've used would be there in every current zip tool one could download.
This said, your concerns are legit. The main problem is that we are wrapping a command here, and that this command lacks a feature so basic we have to build a little script every time... very unconvenient.
Didn't know about nx::zip. It would be far better of course! Maybe I could use the same trick we did on util::http and check for the platform: if Naviserver -> nx::zip, otherwise the command hack.