mirror of
https://github.com/privatevoid-net/nix-super.git
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eb7d7780b1
This is needed to avoid this https://github.com/mesonbuild/meson/issues/13774 when we go back to making our subproject directory `src`.
230 lines
8.6 KiB
Markdown
230 lines
8.6 KiB
Markdown
# Contributing documentation
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Improvements to documentation are very much appreciated, and a good way to start out with contributing to Nix.
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This is how you can help:
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- Address [open issues with documentation](https://github.com/NixOS/nix/issues?q=is%3Aissue+is%3Aopen+label%3Adocumentation)
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- Review [pull requests concerning documentation](https://github.com/NixOS/nix/pulls?q=is%3Apr+is%3Aopen+label%3Adocumentation)
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Incremental refactorings of the documentation build setup to make it faster or easier to understand and maintain are also welcome.
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## Building the manual
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Build the manual from scratch:
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```console
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nix-build -E '(import ./.).packages.${builtins.currentSystem}.nix.doc'
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```
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or
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```console
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nix build .#nix^doc
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```
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and open `./result-doc/share/doc/nix/manual/index.html`.
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To build the manual incrementally, [enter the development shell](./building.md) and run:
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```console
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make manual-html-open -j $NIX_BUILD_CORES
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```
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In order to reflect changes to the [Makefile for the manual], clear all generated files before re-building:
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[Makefile for the manual]: https://github.com/NixOS/nix/blob/master/doc/manual/local.mk
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```console
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rm $(git ls-files doc/manual/ -o | grep -F '.md') && rmdir doc/manual/source/command-ref/new-cli && make manual-html -j $NIX_BUILD_CORES
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```
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## Style guide
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The goal of this style guide is to make it such that
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- The manual is easy to search and skim for relevant information
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- Documentation sources are easy to edit
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- Changes to documentation are easy to review
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You will notice that this is not implemented consistently yet.
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Please follow the guide when making additions or changes to existing documentation.
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Do not make sweeping changes, unless they are programmatic and can be validated easily.
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### Language
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This manual is [reference documentation](https://diataxis.fr/reference/).
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The typical usage pattern is to look up isolated pieces of information.
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It should therefore aim to be correct, consistent, complete, and easy to navigate at a glance.
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- Aim for clarity and brevity.
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Please take the time to read the [plain language guidelines](https://www.plainlanguage.gov/guidelines/) for details.
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- Describe the subject factually.
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In particular, do not make value judgements or recommendations.
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Check the code or add tests if in doubt.
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- Provide complete, minimal examples, and explain them.
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Readers should be able to try examples verbatim and get the same results as shown in the manual.
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Always describe in words what a given example does.
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Non-trivial examples may need additional explanation, especially if they use concepts from outside the given context.
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- Always explain code examples in the text.
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Use comments in code samples very sparingly, for instance to highlight a particular aspect.
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Readers tend to glance over large amounts of code when scanning for information.
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Especially beginners will likely find reading more complex-looking code strenuous and may therefore avoid it altogether.
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If a code sample appears to require a lot of inline explanation, consider replacing it with a simpler one.
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If that's not possible, break the example down into multiple parts, explain them separately, and then show the combined result at the end.
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This should be a last resort, as that would amount to writing a [tutorial](https://diataxis.fr/tutorials/) on the given subject.
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- Use British English.
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This is a somewhat arbitrary choice to force consistency, and accounts for the fact that a majority of Nix users and developers are from Europe.
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### Links and anchors
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Reference documentation must be readable in arbitrary order.
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Readers cannot be expected to have any particular prerequisite knowledge about Nix.
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While the table of contents can provide guidance and full-text search can help, they are most likely to find what they need by following sensible cross-references.
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- Link to technical terms
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When mentioning Nix-specific concepts, commands, options, settings, etc., link to appropriate documentation.
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Also link to external tools or concepts, especially if their meaning may be ambiguous.
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You may also want to link to definitions of less common technical terms.
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Then readers won't have to actively search for definitions and are more likely to discover relevant information on their own.
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> **Note**
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>
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> `man` and `--help` pages don't display links.
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> Use appropriate link texts such that readers of terminal output can infer search terms.
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- Do not break existing URLs between releases.
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There are countless links in the wild pointing to old versions of the manual.
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We want people to find up-to-date documentation when following popular advice.
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- When moving files, update [redirects on nixos.org](https://github.com/NixOS/nixos-homepage/blob/master/netlify.toml).
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This is especially important when moving information out of the Nix manual to other resources.
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- When changing anchors, update [client-side redirects](https://github.com/NixOS/nix/blob/master/doc/manual/redirects.js)
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The current setup is cumbersome, and help making better automation is appreciated.
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The build checks for broken internal links with.
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This happens late in the process, so [building the whole manual](#building-the-manual) is not suitable for iterating quickly.
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[`mdbook-linkcheck`] does not implement checking [URI fragments] yet.
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[`mdbook-linkcheck`]: https://github.com/Michael-F-Bryan/mdbook-linkcheck
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[URI fragments]: https://en.wikipedia.org/wiki/URI_fragment
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### Markdown conventions
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The manual is written in markdown, and rendered with [mdBook](https://github.com/rust-lang/mdBook) for the web and with [lowdown](https://github.com/kristapsdz/lowdown) for `man` pages and `--help` output.
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For supported markdown features, refer to:
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- [mdBook documentation](https://rust-lang.github.io/mdBook/format/markdown.html)
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- [lowdown documentation](https://kristaps.bsd.lv/lowdown/)
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Please observe these guidelines to ease reviews:
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- Write one sentence per line.
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This makes long sentences immediately visible, and makes it easier to review changes and make direct suggestions.
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- Use reference links – sparingly – to ease source readability.
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Put definitions close to their first use.
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Example:
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```
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A [store object] contains a [file system object] and [references] to other store objects.
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[store object]: @docroot@/store/store-object.md
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[file system object]: @docroot@/architecture/file-system-object.md
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[references]: @docroot@/glossary.md#gloss-reference
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```
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- Use admonitions of the following form:
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```
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> **Note**
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>
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> This is a note.
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```
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Highlight examples as such:
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````
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> **Example**
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>
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> ```console
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> $ nix --version
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> ```
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````
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Highlight syntax definitions as such, using [EBNF](https://en.wikipedia.org/wiki/Extended_Backus%E2%80%93Naur_form) notation:
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````
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> **Syntax**
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>
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> *attribute-set* = `{` [ *attribute-name* `=` *expression* `;` ... ] `}`
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````
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### The `@docroot@` variable
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`@docroot@` provides a base path for links that occur in reusable snippets or other documentation that doesn't have a base path of its own.
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If a broken link occurs in a snippet that was inserted into multiple generated files in different directories, use `@docroot@` to reference the `doc/manual/source` directory.
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If the `@docroot@` literal appears in an error message from the [`mdbook-linkcheck`] tool, the `@docroot@` replacement needs to be applied to the generated source file that mentions it.
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See existing `@docroot@` logic in the [Makefile for the manual].
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Regular markdown files used for the manual have a base path of their own and they can use relative paths instead of `@docroot@`.
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## API documentation
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[Doxygen API documentation] is available online.
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You can also build and view it yourself:
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[Doxygen API documentation]: https://hydra.nixos.org/job/nix/master/internal-api-docs/latest/download-by-type/doc/internal-api-docs
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```console
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$ nix build .#hydraJobs.internal-api-docs
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$ xdg-open ./result/share/doc/nix/internal-api/html/index.html
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```
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or inside `nix-shell` or `nix develop`:
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```console
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$ mesonConfigurePhase
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$ ninja src/internal-api-docs/html
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$ xdg-open src/internal-api-docs/html/index.html
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```
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## C API documentation
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Note that the C API is not yet stable.
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[C API documentation] is available online.
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You can also build and view it yourself:
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[C API documentation]: https://hydra.nixos.org/job/nix/master/external-api-docs/latest/download-by-type/doc/external-api-docs
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```console
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$ nix build .#hydraJobs.external-api-docs
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$ xdg-open ./result/share/doc/nix/external-api/html/index.html
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```
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or inside `nix-shell` or `nix develop`:
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```
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$ mesonConfigurePhase
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$ ninja src/external-api-docs/html
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$ xdg-open src/external-api-docs/html/index.html
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```
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