nixpkgs/nixos/lib/from-env.nix

# TODO: remove this file. There is lib.maybeEnv now
name: default:
let value = builtins.getEnv name; in
if value == "" then default else value
adding two new options: - system.copySystemConfiguration (requested by Ludovic Courtès) - system.extraSystemBuilderCmds svn path=/nixos/trunk/; revision=21406 2010-04-28 14:55:26 +00:00			`# TODO: remove this file. There is lib.maybeEnv now`
* Make eval-config.nix a bit more general to make it easier to build other kinds of configurations (like the installation CD). svn path=/nixos/branches/modular-nixos/; revision=15864 2009-06-05 13:19:39 +00:00			`name: default:`
			`let value = builtins.getEnv name; in`
			`if value == "" then default else value`