nix-direnv

# nix-direnv

![Test](https://github.com/nix-community/nix-direnv/workflows/Test/badge.svg)

A faster, persistent implementation of `direnv`'s `use_nix` and `use_flake`, to
replace the built-in one.

Prominent features:

- significantly faster after the first run by caching the `nix-shell`
  environment
- prevents garbage collection of build dependencies by symlinking the resulting
  shell derivation in the user's `gcroots` (Life is too short to lose your
  project's build cache if you are on a flight with no internet connection)

## Why not use `lorri` instead?

Compared to [lorri](https://github.com/nix-community/lorri), nix-direnv is
simpler (and requires no external daemon). Additionally, lorri can sometimes
re-evaluate the entirety of nixpkgs on every change (leading to perpetual high
CPU load).

## Installation

Requirements:

- bash 4.4
- nix 2.4 or newer
- direnv 2.21.3 or newer

> [!WARNING]\
> We assume that [direnv](https://direnv.net/) is installed properly because
> nix-direnv IS NOT a replacement for regular direnv _(only some of its
> functionality)_.

> [!NOTE]\
> nix-direnv requires a modern Bash. MacOS ships with bash 3.2 from 2007. As a
> work-around we suggest that macOS users install `direnv` via Nix or Homebrew.
> There are different ways to install nix-direnv, pick your favourite:

<details>
  <summary> Via home-manager (Recommended)</summary>

### Via home-manager

Note that while the home-manager integration is recommended, some use cases
require the use of features only present in some versions of nix-direnv. It is
much harder to control the version of nix-direnv installed with this method. If
you require such specific control, please use another method of installing
nix-direnv.

In `$HOME/.config/home-manager/home.nix` add

```Nix
{
  # ...other config, other config...

  programs = {
    direnv = {
      enable = true;
      enableBashIntegration = true; # see note on other shells below
      nix-direnv.enable = true;
    };

    bash.enable = true; # see note on other shells below
  };
}
```

Check the current
[Home Manager Options](https://home-manager-options.extranix.com/?query=direnv)
for integration with shells other than Bash. Be sure to also allow
`home-manager` to manage your shell with `programs.<your_shell>.enable = true`.

</details>
<details>
  <summary>Direnv's source_url</summary>

### Direnv source_url

Put the following lines in your `.envrc`:

```bash
if ! has nix_direnv_version || ! nix_direnv_version 3.2.0; then
  source_url "https://raw.githubusercontent.com/nix-community/nix-direnv/3.2.0/direnvrc" "sha256-hW6NC1JHue3IjZN3uDM6l6I2PMaauqd2D7hXYJ1Zfr4="
fi
```

</details>

<details>
  <summary>Via system configuration on NixOS</summary>

### Via system configuration on NixOS

For NixOS 23.05+ all that's required is

```Nix
{
  programs.direnv.enable = true;
}
```

other available options are:

```Nix
{ pkgs, ... }: {
  #set to default values
  programs.direnv = {
    package = pkgs.direnv;
    silent