I dabbled in using Nix for this sort of thing, but it's rather painful to invoke the "Nix language" itself. In Nix 1.x we can evaluate a Nix expression (e.g. a

I dabbled in using Nix for this sort of thing, but it's rather painful to invoke the "Nix language" itself. In Nix 1.x we can evaluate a Nix expression (e.g. a templated string) like this: $ nix-instantiate --eval --read-write-mode -E 'Nix code goes here' That Nix code could be a file, or an import, or whatever. This is slightly improved with Nix 2.x: $ nix eval '(Nix code goes here)' Still, it's not particularly well suited to string processing from the commandline like this. We're closer to Nix's comfortable territory if we use it to build a config file, e.g. $ nix-build -E 'Nix code goes here' Or, more likely: $ nix-build myConfigFileDescription.nix In my experience this is more useful than trying to use Nix as a string processor. Still, if we're using Nix in a project or system, we might be better off using it to build the whole project (e.g. with a 'default.nix' file) or system (using a NixOS module or something). From what I've seen, Guix takes compatibility with non-Guix systems a little closer to heart, e.g. for generating standalone packages that don't require Guix to install/use.