Nix Cookbook

Environment Tasks

Creating Shell Scripts

Arbitrary system shell scripts can be created with pkgs.writeScriptBin. It creates a derivation which you add to environment.systemPackages.

{ config, pkgs, lib, ... }:

with lib;

let
  helloWorld = pkgs.writeScriptBin "helloWorld" ''
#!${pkgs.stdenv.shell}
echo Hello World'';

in {
  config.environment.systemPackages = [ helloWorld ];
}

Debugging

Common Errors

Bad configuration option: gssapikexalgorithms

Found when using an SSH binary from Nix on typically RPM-based distros like CentOS, Fedora, Scientific Linux, Redhat, etc. The quick fix: Just comment out the configuration option in the ssh config file, you probably don't need it.

Desktop Environment does not find .desktop files

IF your DE does not look in $HOME/.nix-profile/share for .desktop files. You need to add that path to the XDG_DATA_DIRS, the position reflects precedence so files in earlier directories shadow files in later directories. This can be accomplished in various ways depending on your login manager, see Arch wiki: Xprofile for more information. For example using ~/.xprofile as follows:

$ export XDG_DATA_DIRS=$HOME/.nix-profile/share:/usr/local/share:/usr/share

Notice that you have to include the default locations on your system, otherwise they will be overwritten. Find out the proper paths using echo $XDG_DATA_DIRS. (Note: export XDG_DATA_DIRS=$HOME/.nix-profile/share:$XDG_DATA_DIRS did not work, XDG_DATA_DIRS ended up containing only $HOME/.nix-profile/share: which isn't even a valid path.)