[Axiom-developer] Check for item in PATH in Emacs?

[C Y]

Does anybody know of a way to check for, say, "axiom" in the PATH on a
particular system from Emacs?  Trying to run something via comint seems
to result in an error which stops everything.  I'm trying to first run
"axiom" if it's available (it turns out graphics do work when run from
the Emacs buffer) and if it isn't available fall back to "AXIOMsys".  I
know I could do some hackery with running "which axiom" on Linux but
I'm hoping for something more straightforward and portable.

Cheers,
CY

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