nixpkgs/nixos/doc/manual/contributing-to-this-manual.chapter.md

Contributing to this manual

The [DocBook] and CommonMark sources of the NixOS manual are in the nixos/doc/manual subdirectory of the Nixpkgs repository. This manual uses the Nixpkgs manual syntax.

You can quickly check your edits with the following:

$ cd /path/to/nixpkgs
$ $EDITOR doc/nixos/manual/... # edit the manual
$ nix-build nixos/release.nix -A manual.x86_64-linux

If the build succeeds, the manual will be in ./result/share/doc/nixos/index.html.

There's also a convenient development daemon.

The above instructions don't deal with the appendix of available configuration.nix options, and the manual pages related to NixOS. These are built, and written in a different location and in a different format, as explained in the next sections.

Contributing to the configuration.nix options documentation

The documentation for all the different configuration.nix options is automatically generated by reading the descriptions of all the NixOS options defined at nixos/modules/. If you want to improve such description, find it in the nixos/modules/ directory, and edit it and open a pull request.

To see how your changes render on the web, run again:

$ nix-build nixos/release.nix -A manual.x86_64-linux

And you'll see the changes to the appendix in the path result/share/doc/nixos/options.html.

You can also build only the configuration.nix(5) manual page, via:

$ cd /path/to/nixpkgs
$ nix-build nixos/release.nix -A nixos-configuration-reference-manpage.x86_64-linux

And observe the result via:

$ man --local-file result/share/man/man5/configuration.nix.5

If you're on a different architecture that's supported by NixOS (check file nixos/release.nix on Nixpkgs' repository) then replace x86_64-linux with the architecture. nix-build will complain otherwise, but should also tell you which architecture you have + the supported ones.

Contributing to nixos-* tools' manpages

The manual pages for the tools available in the installation image can be found in Nixpkgs by running (e.g for nixos-rebuild):

$ git ls | grep nixos-rebuild.8

Man pages are written in mdoc(7) format and should be portable between mandoc and groff for rendering (except for minor differences, notably different spacing rules.)

For a preview, run man --local-file path/to/file.8.

Being written in mdoc, these manpages use semantic markup. This following subsections provides a guideline on where to apply which semantic elements.

Command lines and arguments

In any manpage, commands, flags and arguments to the current executable should be marked according to their semantics. Commands, flags and arguments passed to other executables should not be marked like this and should instead be considered as code examples and marked with Ql.

• Use Fl to mark flag arguments, Ar for their arguments.
• Repeating arguments should be marked by adding an ellipsis (spelled with periods, ...).
• Use Cm to mark literal string arguments, e.g. the boot command argument passed to nixos-rebuild.
• Optional flags or arguments should be marked with Op. This includes optional repeating arguments.
• Required flags or arguments should not be marked.
• Mutually exclusive groups of arguments should be enclosed in curly brackets, preferably created with Bro/Brc blocks.

When an argument is used in an example it should be marked up with Ar again to differentiate it from a constant. For example, a command with a --host name option that calls ssh to retrieve the host's local time would signify this thusly:

This will run
.Ic ssh Ar name Ic time
to retrieve the remote time.

Paths, NixOS options, environment variables

Constant paths should be marked with Pa, NixOS options with Va, and environment variables with Ev.

Generated paths, e.g. result/bin/run-hostname-vm (where hostname is a variable or arguments) should be marked as Ql inline literals with their variable components marked appropriately.

• When hostname refers to an argument, it becomes .Ql result/bin/run- Ns Ar hostname Ns -vm
• When hostname refers to a variable, it becomes .Ql result/bin/run- Ns Va hostname Ns -vm

Code examples and other commands

In free text names and complete invocations of other commands (e.g. ssh or tar -xvf src.tar) should be marked with Ic, fragments of command lines should be marked with Ql.

Larger code blocks or those that cannot be shown inline should use indented literal display block markup for their contents, i.e.

.Bd -literal -offset indent
...
.Ed

Contents of code blocks may be marked up further, e.g. if they refer to arguments that will be substituted into them:

.Bd -literal -offset indent
{
  config.networking.hostname = "\c
.Ar hostname Ns \c
";
}
.Ed