Nix shell env template

shell.nix

# This shell defines a development environment for a c project.
{
  pkgs ? import (fetchTarball "https://github.com/NixOS/nixpkgs/archive/39e6bf76474ce742eb027a88c4da6331f0a1526f.tar.gz") {}
}:

# Override packages if necessary
#let
#  newExample = pkgs.example.override {
#    option = example
#  };
#in

# for changing the gcc environment use
# pkgs.mkShell.override {stdenv = pkgs.gcc10Stdenv;} {
pkgs.mkShell {
   buildInputs = with pkgs; [
       #packages
   ];

   shellHook = ''
      # start user default shell
      SHELL=$(awk -F: -v user="$USER" '$1 == user {print $NF}' /etc/passwd)
      $SHELL
  '';

   NIX_ENFORCE_PURITY=0;
}