EINVAL being returned by shutdown() call

[jay dubb]

   I am posting this for a friend of mine who doesn't have access
to USENET, so please respond directly to mlevin at jade.tufts.edu.

   I am using shutdown(i,2) to close a socket whose descriptor was i.
For some reason, this call sets errno to 22 - EINVAL, which is not
listed as a possible errno return by the man page for shutdown(). Does
anyone know what causes shutdown() to set this?

					Mike Levin (mlevin at jade.tufts.edu)