Okay, based on your instructions I’ve created a little helper module that copies the exec-port binary into the systems temp folder and it is currently working well:

defmodule ErlexecInit do
  @moduledoc """
  Responsible for starting Erlexec in a manner compatible with escripts. By
  default the exec-port binary is compiled into erlexec's priv folder, but since
  escripts don't have access to the priv directories we need to store the binary
  into the code and then on startup we need to write it out into the system's
  tempdirectory

  Reference: https://forum.elixirforum.net/t/unable-to-run-erlexec-in-a-escript/21603
  """

  use GenServer

  @exec_port_binary_path Application.app_dir(:erlexec, [
                           "priv",
                           :erlang.system_info(:system_architecture),
                           "exec-port"
                         ])

  @execport_binary File.read!(@exec_port_binary_path)

  def start_link(_, name \\ __MODULE__) do
    GenServer.start_link(__MODULE__, nil, name: name)
  end

  @impl GenServer
  def init(_) do
    port_exe_path =
      System.tmp_dir!()
      |> Path.join("tmp-exec-port-#{System.unique_integer([:positive])}")
      |> String.to_charlist()

    File.write!(port_exe_path, @execport_binary)
    File.chmod!(port_exe_path, 0o700)

    :exec.start(portexe: port_exe_path)

    {:ok, []}
  end
end

I haven’t looked at this code in a while but I think you’re referring to this part of the snippet above:

:exec.start(portexe: port_exe_path)

I’m calling that function in a GenServer that is part of my supervision tree but you would likely also be okay if you dropped that code directly into your application.ex file in the start/2 function.

Here’s the full code if you want to take a look ls_proxy/ls_proxy/lib/erlexec_init.ex at 2435d956f924813021493a9b292f81b81a7eb00d · axelson/ls_proxy · GitHub

axelson, thanks for your quick response.

That did indeed work, I misunderstood the purpose of that line of code, but it makes sense now.

Best Regards,