nixcfg

Command line utility to query and modify .nix files.

Usage

nixcfg 0.1.0
Grégoire Geis <git@gregoirege.is>
Command line utility to query and modify .nix files.

USAGE:
    nixcfg [FLAGS] [OPTIONS] <SUBCOMMAND>

FLAGS:
    -h, --help        Prints help information
    -i, --in-place    Modify in place instead of printing result to stdout.
    -V, --version     Prints version information

OPTIONS:
    -f, --file <input>    Input .nix file to query or modify. [default: /etc/nixos/configuration.nix]

SUBCOMMANDS:
    get     Get the value at the given path.
    set     Set the value at the given path.

Examples

Let's consider the following file:

# file.nix
{ pkgs, config, ... }:

{
  environment.systemPackages = with pkgs; [ ];

  networking.firewall.enable = true;
  networking.firewall.allowedTCPPorts = [ 80 8080 8000 24800 ];

  nixpkgs.config = { allowBroken = false; allowUnfree = true; };
}

Querying values

• nixpkg -f file.nix get environment.systemPackages yields with pkgs; [ ].
• nixpkg -f file.nix get nixpkgs.config yields { allowBroken = false; allowUnfree = true; }.
• nixpkg -f file.nix get nixpkgs.config.allowBroken yields false.

Please note that nixcfg does not recognize values belonging to a same object.

• nixpkg -f file.nix get networking.firewall.enable yields true.
• nixpkg -f file.nix get networking.firewall.allowedTCPPorts yields [ 80 8080 8000 24800 ].
• nixpkg -f file.nix get networking.firewall fails to find a matching value.

Updating values

nixpkg -f file.nix set networking.firewall.enable false

yields

# file.nix
{ pkgs, config, ... }:

{
  environment.systemPackages = with pkgs; [ ];

  networking.firewall.enable = false;
  networking.firewall.allowedTCPPorts = [ 80 8080 8000 24800 ];

  nixpkgs.config = { allowBroken = false; allowUnfree = true; };
}

To do

• Add ability to insert the value, if the key did not previously exist.

Disclaimer

This project is very new, and has only been tested in limited test suites.
Use at your own risks.