foo.nix

{ pkgs ? import <nixpkgs> { config.allowUnfree = true; } }:
let
  src = pkgs.writeTextFile {
    name = "Main.hs";
    text = ''module Main where
             main = print =<< readFile "/opt/cisco/anyconnect/lol.txt"
           '';
  };
  lol = pkgs.writeTextFile { name = "lol.txt"; text = "loooooool\n"; };
  app = pkgs.stdenv.mkDerivation {
    name = "anyconnect";
    inherit src;
    buildInputs = with pkgs; [ ghc makeWrapper ];
    buildCommand = ''
      mkdir -p $out/bin
      cp -v ${lol} $out
      ghc $src -o $out/bin/foo
      wrapProgram $out/bin/foo \
        --set LD_PRELOAD "${pkgs.libredirect}/lib/libredirect.so" \
        --set NIX_REDIRECTS /opt/cisco/anyconnect=$out
   '';
  };
   test = pkgs.writeScriptBin "runner" ''
      ${pkgs.strace}/bin/strace ${app}/bin/foo
      ${app}/bin/foo
   '';
in
  test