flake shell example

.envrc

NIX_CONFIG="extra-experimental-features = nix-command flakes" use flake

flake.nix

{
  description = "My awesome flake";

  # update with `nix flake update`
  inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-23.05";
  #inputs.nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";

  outputs = { self, nixpkgs, ... } @ inputs: let
    forAllSystems = f: nixpkgs.lib.genAttrs nixpkgs.lib.systems.flakeExposed (system: f rec {
      inherit system;
      pkgs = nixpkgs.legacyPackages.${system};
      lib  = nixpkgs.legacyPackages.${system}.lib;
    });
  in {

    devShells = forAllSystems ({ pkgs, ... }: rec {

      default = pkgs.mkShell {
        packages = [
          pkgs.bashInteractive
        ];
      };

    });

  };
}

in response to https://lobste.rs/s/xc37sv/nix_shell_template