Understanding `<nixpkgs>/modules`

modules/README.md

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# `<nixpkgs>/modules`

This directory hosts subdirectories representing each module [class](https://nixos.org/manual/nixpkgs/stable/#module-system-lib-evalModules-param-class) for which the `nixpkgs` repository has user-importable modules.

Exceptions:
- `_class = "nixos";` modules go in the `<nixpkgs>/nixos/modules` tree
- modules whose only purpose is to test code in this repository

The emphasis is on _importable_ modules, i.e. ones that aren't inherent to and built into the Module System application.

Chunks

b7752b94 (1st chunk of `modules/README.md`)

Title: Understanding `<nixpkgs>/modules`

Summary

The `<nixpkgs>/modules` directory contains subdirectories for user-importable module classes within the `nixpkgs` repository. These are modules that are not integral to the Module System application itself. Notable exceptions include modules of the `nixos` class, which reside in `<nixpkgs>/nixos/modules`, and modules whose sole function is to test code within the repository.