mpxcall - multiplexor and channel interface
mpxcall(arg1, arg2, arg3, cmd)
Mpxcall supplies a primitive interface to the kernel used by the rou-
tines listed below. Each routine that uses mpxcall passes an integer
cmd as the fourth argument. These are defined in /usr/include/mx.h.
Mpxcall always returns an integer which is to be interpreted in accor-
dance with the definition of cmd.
group(2), join(2), extract(2), connect(2), chan(2), attach(2),
The value -1 is returned on error.