How to add a file to /etc in NixOS?

To create a file in /etc on NixOS, use environment.etc in configuration.nix. Here's an example:

environment.etc = { # Creates /etc/nanorc nanorc = { text = '' whatever you want to put in the file goes here. ''; # The UNIX file mode bits mode = "0440"; }; }; 

Additionally, you can also add a file from a path with:

environment.etc = { somerc.source = /etc/somerc; }; 

Or a directory:

environment.etc = { aDir.source = ./aDir; }; 

Or a package path:

environment.etc = { "X11/xorg.conf.d/90-super.conf".source = "${pkgs.displayfix}/share/displayfix/data/90-super.conf"; };