.config/nixpkgs/helpers: Add mkShellPure.nix

2 files changed, 39 insertions, 2 deletions

diff --git a/.config/nixpkgs/helpers/mkShellMinimal.nix b/.config/nixpkgs/helpers/mkShellMinimal.nix
index dc339ec..057dd6e 100644
--- a/.config/nixpkgs/helpers/mkShellMinimal.nix
+++ b/.config/nixpkgs/helpers/mkShellMinimal.nix
@@ -33,8 +33,8 @@ derivation ({
     text = ''
       set -e
       PATH=
-      for p in ${toString packages}; do
-        export PATH=$p/bin:$PATH
+      for package in ${toString packages}; do
+        export PATH=$package/bin:$PATH
       done
       ${shellHook}
     '';
diff --git a/.config/nixpkgs/helpers/mkShellPure.nix b/.config/nixpkgs/helpers/mkShellPure.nix
new file mode 100644
index 0000000..de44c67
--- /dev/null
+++ b/.config/nixpkgs/helpers/mkShellPure.nix
@@ -0,0 +1,37 @@
+### Pure version of mkShellMinimal that clears all environment variables.
+### Derived Source:  https://github.com/NixOS/nixpkgs/commit/459771518d44f60b59a19381d07b12297908215d
+### Article: https://fzakaria.com/2021/08/02/a-minimal-nix-shell.html
+
+{ writeTextFile, writeScript, system }:
+
+{ shellHook ? "", packages ? [ ], ... }@attrs:
+derivation ({
+  inherit system;
+
+  name = "pure-nix-shell";
+
+  "stdenv" = writeTextFile rec {
+    name = "setup";
+    executable = true;
+    destination = "/${name}";
+    text = ''
+      set -e
+      for package in ${toString packages}; do
+        export NEW_PATH=$package/bin:$NEW_PATH
+      done
+      exec /usr/bin/env --ignore-environment /bin/sh -c "
+       export PATH=$NEW_PATH
+      ${shellHook}
+      /bin/sh
+      "
+    '';
+  };
+
+  builder = writeScript "builder.sh" ''
+    #!/bin/sh
+    echo
+    echo "This derivation is not meant to be built, unless you want to capture the dependency closure.";
+    echo
+    export > $out
+  '';
+} // attrs)