Nixpkgs Package Categories and Conventions

- **If it’s a _terminal emulator_:** - `applications/terminal-emulators` (e.g. `alacritty` or `rxvt` or `termite`) - **If it’s a _file manager_:** - `applications/file-managers` (e.g. `mc` or `ranger` or `pcmanfm`) - **If it’s for _video playback / editing_:** - `applications/video` (e.g. `vlc`) - **If it’s for _graphics viewing / editing_:** - `applications/graphics` (e.g. `gimp`) - **If it’s for _networking_:** - **If it’s a _mailreader_:** - `applications/networking/mailreaders` (e.g. `thunderbird`) - **If it’s a _newsreader_:** - `applications/networking/newsreaders` (e.g. `pan`) - **If it’s a _web browser_:** - `applications/networking/browsers` (e.g. `firefox`) - **Else:** - `applications/networking/misc` - **Else:** - `applications/misc` **If it’s _data_ (i.e., does not have a straight-forward executable semantics):** - **If it’s a _font_:** - `data/fonts` - **If it’s an _icon theme_:** - `data/icons` - **If it’s related to _SGML/XML processing_:** - **If it’s an _XML DTD_:** - `data/sgml+xml/schemas/xml-dtd` (e.g. `docbook`) - **If it’s an _XSLT stylesheet_:** (Okay, these are executable...) - `data/sgml+xml/stylesheets/xslt` (e.g. `docbook-xsl`) - **If it’s a _theme_ for a _desktop environment_, a _window manager_ or a _display manager_:** - `data/themes` **If it’s a _game_:** - `games` **Else:** - `misc` </details> # Conventions The key words _must_, _must not_, _required_, _shall_, _shall not_, _should_, _should not_, _recommended_, _may_, and _optional_ in this section are to be interpreted as described in [RFC 2119](https://tools.ietf.org/html/rfc2119). Only _emphasized_ words are to be interpreted in this way. ## Package naming In Nixpkgs, there are generally three different names associated with a package: - The `pname` attribute of the derivation. This is what most users see, in particular when using `nix-env`. - The attribute name used for the package in the [`pkgs/by-name` structure](./by-name/README.md) or in [`all-packages.nix`](./top-level/all-packages.nix), and when passing it as a dependency in recipes. - The filename for (the directory containing) the Nix expression. Most of the time, these are the same. For instance, the package `e2fsprogs` has a `pname` attribute `"e2fsprogs"`, is bound to the attribute name `e2fsprogs` in `all-packages.nix`, and the Nix expression is in `pkgs/os-specific/linux/e2fsprogs/default.nix`. Follow these guidelines: - For the `pname` attribute: - It _should_ be identical to the upstream package name. - It _must not_ contain uppercase letters. Example: Use `"mplayer"` instead of `"MPlayer"` - For the package attribute name: - It _must_ be a valid identifier in Nix. - If the `pname` starts with a digit, the attribute name _should_ be prefixed with an underscore. Otherwise the attribute name _should not_ be prefixed with an underline. Example: The corresponding attribute name for `0ad` should be `_0ad`. - New attribute names _should_ be the same as the value in `pname`. Hyphenated names _should not_ be converted to [snake case](https://en.wikipedia.org/wiki/Snake_case) or [camel case](https://en.wikipedia.org/wiki/Camel_case). This was done historically, but is not necessary any more. [The Nix language allows dashes in identifiers since 2012](https://github.com/NixOS/nix/commit/95c74eae269b2b9e4bc514581b5caa1d80b54acc). - If there are multiple versions of a package, this _should_ be reflected in the attribute names in `all-packages.nix`. Example: `json-c_0_9` and `json-c_0_11` If there is an obvious “default” version, make an extra attribute. Example: `json-c = json-c_0_9;` See also [versioning][versioning]. ## Versioning These are the guidelines the `version` attribute of a package: - It _must_ start with a digit. This is required for backwards-compatibility with [how `nix-env` parses derivation names](https://nix.dev/manual/nix/latest/command-ref/nix-env#selectors).

This section continues the categorization of Nixpkgs packages, covering applications like terminal emulators, file managers, video/graphics editing, and networking tools, as well as data types such as fonts, icon themes, and SGML/XML related items. It also includes categories for themes and games, with a 'misc' catch-all. The text then shifts to naming conventions in Nixpkgs, focusing on the 'pname' attribute, package attribute names, and filename conventions, emphasizing consistency with upstream names and valid Nix identifiers. Finally, it touches on versioning guidelines, requiring the 'version' attribute to start with a digit for compatibility reasons.