Files
lix/doc/manual/src/command-ref/conf-file.md
T
eldritch horrors 725f5cd358 docs: redo content generation for mdbook and manual
manpages can be rendered using the markdown output of mdbook, the rest
of the manual can generated out of the main doc/manual source tree. we
still use lowdown to actually render manpages instead of eg mdbook-man
because lowdown does generate reasonably good manpages (though that is
also somewhat debatable, but they're a lot better than mdbook-man).

doing this not only lets us drastically simplify the lowdown pipeline,
but also remove all custom {{#include}} handling since now mdbook does
all of it, even for the manpage builds. even the lowdown wrapper isn't
entirely necessary because lowdown can take all wrapper arguments with
command line flags rather than bits of input file content.

This also implements running mdbook in Meson, in order to generate the
manpages. The mdbook outputs are also installed in the usual location.

Co-authored-by: Qyriad <qyriad@qyriad.me>

Change-Id: I60193f9fd0f15d48872f071af35855cda2a0f40b
2024-04-11 13:32:06 +00:00

2.8 KiB

Name

nix.conf - Nix configuration file

Description

Nix supports a variety of configuration settings, which are read from configuration files or taken as command line flags.

Configuration file

By default Nix reads settings from the following places, in that order:

  1. The system-wide configuration file sysconfdir/nix/nix.conf (i.e. /etc/nix/nix.conf on most systems), or $NIX_CONF_DIR/nix.conf if NIX_CONF_DIR is set.

    Values loaded in this file are not forwarded to the Nix daemon. The client assumes that the daemon has already loaded them.

  2. If NIX_USER_CONF_FILES is set, then each path separated by : will be loaded in reverse order.

    Otherwise it will look for nix/nix.conf files in XDG_CONFIG_DIRS and XDG_CONFIG_HOME. If unset, XDG_CONFIG_DIRS defaults to /etc/xdg, and XDG_CONFIG_HOME defaults to $HOME/.config as per XDG Base Directory Specification.

  3. If NIX_CONFIG is set, its contents are treated as the contents of a configuration file.

File format

Configuration files consist of name = value pairs, one per line. Comments start with a # character.

Example:

keep-outputs = true       # Nice for developers
keep-derivations = true   # Idem

Other files can be included with a line like include <path>, where <path> is interpreted relative to the current configuration file. A missing file is an error unless !include is used instead.

A configuration setting usually overrides any previous value. However, for settings that take a list of items, you can prefix the name of the setting by extra- to append to the previous value.

For instance,

substituters = a b
extra-substituters = c d

defines the substituters setting to be a b c d.

Unknown option names are not an error, and are simply ignored with a warning.

Command line flags

Configuration options can be set on the command line, overriding the values set in the configuration file:

  • Every configuration setting has corresponding command line flag (e.g. --max-jobs 16). Boolean settings do not need an argument, and can be explicitly disabled with the no- prefix (e.g. --keep-failed and --no-keep-failed).

    Unknown option names are invalid flags (unless there is already a flag with that name), and are rejected with an error.

  • The flag --option <name> <value> is interpreted exactly like a <name> = <value> in a setting file.

    Unknown option names are ignored with a warning.

The extra- prefix is supported for settings that take a list of items (e.g. --extra-trusted users alice or --option extra-trusted-users alice).

Available settings

{{#include @generated@/command-ref/conf-file.md}}