Locales

Notes when setting supportedLocales and extraLocaleSettings

Beaware when setting up your locale variables. The setting i18n.supportedLocales requires a different format to i18n.extraLocaleSettings.

The setting i18n.supportedLocales requries the requires the language string with the added /UTF-8

"en_US.UTF-8/UTF-8"
"nl_NL.UTF-8/UTF-8"

The setting i18n.extraLocaleSettings, however, requires the language string without any suffix.

LC_MESSAGES = "en_US.UTF-8"
LC_TIME = "de_DE.UTF-8"

Otherwise, your locale settings will likely not work.

Troubleshooting when using nix on non-NixOS linux distributions

You may need to set the environmental variable LOCALE_ARCHIVE to point to your system's locale-archive. The following can be added to your .zshenv (zsh) or .profile (bash) and applies to Debian, Red Hat, and Arch derivatives:

export LOCALE_ARCHIVE=/usr/lib/locale/locale-archive

And if that file from the local system is somehow broken:

# May require a one-time installation with:
nix profile install nixpkgs#glibcLocales
# Using nix profile
export LOCALE_ARCHIVE="$(nix profile list --json | jq '.elements[] | select(.attrPath? and (.attrPath | type == "string") and (.attrPath | endswith("glibcLocales"))) | .storePaths[0]')/lib/locale/locale-archive"

# Legacy usage with `nix-env`: May require a one-time installation with: nix-env -iA nixpkgs.glibcLocales
export LOCALE_ARCHIVE="$(nix-env --installed --no-name --out-path --query glibc-locales)/lib/locale/locale-archive"

Enable locale support in Nix shell

To support locales within a Nix shell, for example to get localised command output, you need to do something similar:

pkgs.mkShell {
  # [other code omitted]
  LOCALE_ARCHIVE = "${pkgs.glibcLocales}/lib/locale/locale-archive";
}