I can think of solving this a number of ways. Do you have distribution available? If not i would use a domain socket if you are on a Linux or OSx machine. (i think OSX supports unix domain sockets)
From an iex session:

{:ok, sock} = :gen_udp.open(0, [{:ifaddr, {:local, '/tmp/testsockin'}}])

and from a shell

echo 'Hello, World!' | socat - UNIX-SENDTO:/tmp/testsockin

Well, that was unexpectedly tediuous …

• Elixir port using named pipe via UNDOCUMENTED open_port/2 functionality
• Elixir port using named pipe with forwarding script
• Elixir port using named pipe with releasing script

I know how to setup a domain socket and not a named pipe in Elixir

Just in case, you can use something like config :kernel, inet_dist_use_interface: {127, 0, 0, 1} to bind only on localhost (loopback).