Merge fort-nix/nix-bitcoin#399: examples: Fix shell on non-Linux systems

46af0b1a8d examples: fix shell on non-Linux systems (Erik Arvstedt)

Pull request description:

ACKs for top commit:
  jonasnick:
    ACK 46af0b1a8d

Tree-SHA512: bc3c24c75b2d26a30f9f4f88700da8a78d8276802b47ddaf3d52097ba6ed16a7b7ca662085e2775a2cd1654b07c1759c36918ee0ab05eb90fbfeac3265576510

examples/README.md

@@ -18,11 +18,11 @@ By default, [`configuration.nix`](configuration.nix) enables `bitcoind` and `cli
   Requires: [Nix](https://nixos.org/), a systemd-based Linux distro and root privileges
 
 - [`./deploy-qemu-vm.sh`](deploy-qemu-vm.sh) creates a QEMU VM.\
-  Requires: [Nix](https://nixos.org/nix/)
+  Requires: [Nix](https://nixos.org/nix/), Linux
 
 - [`./deploy-krops.sh`](deploy-krops.sh) creates a QEMU VM and deploys a
   nix-bitcoin configuration to it using [krops](https://github.com/krebs/krops).\
-  Requires: [Nix](https://nixos.org/nix/)
+  Requires: [Nix](https://nixos.org/nix/), Linux
 
 - [`./deploy-container-minimal.sh`](deploy-container-minimal.sh) creates a
   container defined by [importable-configuration.nix](importable-configuration.nix).\

helper/makeShell.nix

@@ -1,20 +1,20 @@
 { configDir, shellVersion ? null, extraShellInitCmds ? (pkgs: "") }:
 let
+  inherit (pkgs) lib;
   nixpkgs = (import ../pkgs/nixpkgs-pinned.nix).nixpkgs;
   pkgs = import nixpkgs {};
   nbPkgs = import ../pkgs { inherit pkgs; };
   cfgDir = toString configDir;
+  path = lib.optionalString pkgs.stdenv.isLinux ''
+    export PATH="${lib.makeBinPath [ nbPkgs.extra-container ]}''${PATH:+:}$PATH"
+  '';
 in
-with pkgs;
-stdenv.mkDerivation rec {
+pkgs.stdenv.mkDerivation {
   name = "nix-bitcoin-environment";
 
-  path = lib.makeBinPath [ nbPkgs.extra-container ];
-
   shellHook = ''
     export NIX_PATH="nixpkgs=${nixpkgs}:nix-bitcoin=${toString ../.}:."
-    export PATH="${path}''${PATH:+:}$PATH"
-
+    ${path}
     export NIX_BITCOIN_EXAMPLES_DIR="${cfgDir}"
 
     # Set isInteractive=1 if
@@ -111,7 +111,7 @@ stdenv.mkDerivation rec {
     }
 
     if [[ $isInteractive ]]; then
-      ${figlet}/bin/figlet "nix-bitcoin"
+      ${pkgs.figlet}/bin/figlet "nix-bitcoin"
       echo 'Enter "h" or "help" for documentation.'
     fi