title: How can I install binary file into NixOS
body: <p>I'm trying to install external binary inside NixOS, using declarative ways. Inside nix-pkg manual, I found such way of getting external binary inside NixOS</p>
  <pre><code>{ pkgs ? import &lt;nixpkgs&gt; {} }:
  pkgs.stdenv.mkDerivation {
    name = &quot;goss&quot;;
    src = pkgs.fetchurl {
      url = &quot;https://github.com/aelsabbahy/goss/releases/download/v0.3.13/goss-linux-amd64&quot;;
      sha256 = &quot;1q0kfdbifffszikcl0warzmqvsbx4bg19l9a3vv6yww2jvzj4dgb&quot;;
    };
    phases = [&quot;installPhase&quot;];             
    installPhase = ''
    
    '';
  </code></pre>
  <p>But I'm wondering, what should I add inside <code>InstallPhase</code>, to make this binary being installed inside the system?</p>