Attempt fix with autoelfpatch

packages/linuxcnc-ethercat/default.nix

@@ -13,17 +13,28 @@ stdenv.mkDerivation rec {
     sha256 = "SjFkcNl/4AlsMeIw5Hg9Kp5mIIV9KFUYodXV6lAi3/A=";
   };
 
-  nativeBuildInputs = with pkgs; [ which expat ];
+  nativeBuildInputs = with pkgs; [
+    autoPatchelfHook
+    which
+    expat
+  ];
 
   buildInputs = [ linuxcnc ethercat ];
 
+  preBuild = ''
+    #addAutoPatchelfSearchPath ${placeholder "out"}/lib/linuxcnc/modules/
+  '';
+
   installFlags = [
+    "prefix=${placeholder "out"}"
+    #"RUN_IN_PLACE=YES"
     "DESTDIR=${placeholder "out"}"
     "EMC2_HOME=''"
     "LIBDIR=''"
     "RTLIBDIR='/lib/linuxcnc/modules'"
   ];
 
+
   meta = with lib; {
     description = "LinuxCNC ethercat interop";
     platforms = platforms.linux;

packages/linuxcnc/default.nix

@@ -1,4 +1,4 @@
-{ lib, stdenv, autoreconfHook, wrapGAppsHook, qt5, makeWrapper, fetchFromGitHub, libtool, pkgconfig,
+{ pkgs, lib, stdenv, autoreconfHook, wrapGAppsHook, qt5, makeWrapper, fetchFromGitHub, libtool, pkgconfig,
   readline_5, ncurses, libtirpc, systemd, libmodbus, libusb, glib, gtk2, gtk3, procps, kmod, sysctl,
   util-linux, psmisc, intltool, tcl, tk, bwidget, tkimg, tclx, tkblt, pango, cairo, boost, espeak, gst_all_1,
   python3Full, yapps, gobject-introspection, libGLU, xorg, libepoxy, hicolor-icon-theme, glxinfo, bash
@@ -36,6 +36,7 @@ stdenv.mkDerivation rec {
 
   nativeBuildInputs = [
     autoreconfHook
+    pkgs.autoPatchelfHook
     makeWrapper
     wrapGAppsHook
     qt5.wrapQtAppsHook