defaults2nix

A Go utility to convert macOS defaults output to Nix.

This tool makes it easy to convert macOS system preferences and application settings into declarative Nix configurations for use with nix-darwin or Home Manager.

Features

• Convert macOS defaults to Nix attribute sets
• Support for all standard data types (booleans, numbers, strings, arrays, dictionaries)
• Automatic binary data filtering (skips non-useful binary entries)
• Proper string escaping and quoting
• Preserve nested structures and key ordering

Installation

Using Nix

The easiest way to install is using Nix:

# Run directly from the flake
nix run github:joshryandavis/defaults2nix

# Or install to your profile
nix profile install github:joshryandavis/defaults2nix

Building from Source

Basic Usage

From file

git clone https://github.com/joshryandavis/defaults2nix
cd defaults2nix
go build -o defaults2nix

Usage

Note: For system-level configurations and certain global settings, you may need to run commands with sudo to access all preferences.

Basic Usage - Single Domain

Convert defaults for a specific domain:

# Output to stdout
defaults2nix com.apple.Safari

# Save to file
defaults2nix com.apple.Safari -o safari.nix

All Domains

Convert all system defaults at once:

# Output to stdout (may need sudo for system-level configs)
defaults2nix -all

# Save to file
defaults2nix -all -o all-defaults.nix

# For complete system settings, run as root
sudo defaults2nix -all -o all-defaults.nix

Split by Domain

Convert all domains into separate files:

# Creates individual .nix files for each domain
defaults2nix -split -o ./nix-configs/

# For system-level configs, run as root
sudo defaults2nix -split -o ./nix-configs/

# This creates files like:
# ./nix-configs/com.apple.Safari.nix
# ./nix-configs/com.apple.finder.nix
# ./nix-configs/NSGlobalDomain.nix
# etc.

Command Line Options

Usage: defaults2nix [flags] [domain]

A tool for converting macOS defaults into Nix templates.

Flags:
  -all      Process all defaults from `defaults read`
  -split    Split defaults into individual Nix files by domain
  -o, -out  Output file or directory path

Arguments:
  domain     The domain to convert (e.g., com.apple.dock)

Examples:
  defaults2nix com.apple.Safari
  defaults2nix com.apple.Safari -o safari.nix
  defaults2nix -all -o all-defaults.nix
  defaults2nix -split -o ./configs/
  sudo defaults2nix -all -o all-defaults.nix  # for system configs

Split Top-Level Keys

You can split all top-level keys (bundle IDs, NSGlobalDomain, custom preferences, etc.) into individual files using the -split flag:

Split from file

defaults export > all-defaults.plist
defaults2nix -split -output ./configs all-defaults.plist

Split from stdin

defaults export | defaults2nix -split -output ./configs

# For system-level preferences
sudo defaults export | defaults2nix -split -output ./configs

This will create individual .nix files for each top-level key found in the input:

• com-apple-Safari.nix
• NSGlobalDomain.nix
• Custom_User_Preferences.nix
• loginwindow.nix
• etc.

Command Line Options

• -split: Split top-level keys into individual files
• -output <dir>: Output directory for split files (default: current directory)
• -help: Show usage information

Input Format

The tool processes the standard output format from macOS defaults read commands:

{
    AutoFillCreditCardData = 1;
    AutoOpenSafeDownloads = 0;
    HomePage = "https://www.apple.com/startpage/";
    ExtensionsEnabled = 1;
    FrequentlyVisitedSites = (
        {
            Title = "Example Site";
            URL = "https://example.com/";
            Score = "42.5";
        },
        "Simple String Item"
    );
}

Output Format

Converts to clean Nix attribute set syntax:

{
  AutoFillCreditCardData = true;
  AutoOpenSafeDownloads = false;
  HomePage = "https://www.apple.com/startpage/";
  ExtensionsEnabled = true;
  FrequentlyVisitedSites = [
    {
      Title = "Example Site";
      URL = "https://example.com/";
      Score = 42.5;
    }
    "Simple String Item"
  ];
}

Type Conversions

macOS Format	Nix Format	Notes
1	true	Boolean true
0	false	Boolean false
42	42	Integers preserved
3.14	3.14	Floats preserved
"string"	"string"	Quoted strings
simple	"simple"	Unquoted identifiers become strings
(item1, item2)	[item1 item2]	Arrays to lists
{key = value;}	{key = value;}	Dictionaries to attribute sets
{length = N; bytes = 0x...}	skipped	Binary data filtered out

Key Handling

The tool automatically handles special cases for Nix attribute names:

• Numeric keys: 123 → "123"
• Keys with spaces: key name → "key name"
• Keys with dashes: key-name → "key-name"
• Keys starting with numbers: 1password → "1password"
• Nix keywords: with, let, in, etc. → quoted
• Keys with dots: com.apple.Safari → "com.apple.Safari"

Common Use Cases

Single Application Configuration

# Get Safari settings
defaults2nix com.apple.Safari -o safari.nix

# Use in nix-darwin
system.defaults.CustomUserPreferences."com.apple.Safari" = import ./safari.nix;

Multiple Applications and Global Settings (Split Mode)

# Get Finder settings
defaults2nix com.apple.finder -o finder.nix

# Use in Home Manager
targets.darwin.defaults."com.apple.finder" = import ./finder.nix;

System-wide Settings

# Get global domain settings (may require sudo)
defaults2nix NSGlobalDomain -o global.nix

# For complete system settings
sudo defaults2nix NSGlobalDomain -o global.nix

# Use in nix-darwin
system.defaults.NSGlobalDomain = import ./global.nix;

Complete System Migration

# Export all current settings (run as root for complete coverage)
sudo defaults2nix -split -o ./my-macos-config/

# Then selectively import the ones you want in your Nix configuration

Integration Examples

With nix-darwin

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

{
  system.defaults = {
    # Import converted settings
    NSGlobalDomain = import ./defaults/NSGlobalDomain.nix;

    CustomUserPreferences = {
      "com.apple.Safari" = import ./defaults/com.apple.Safari.nix;
      "com.apple.finder" = import ./defaults/com.apple.finder.nix;
    };
  };
}

With Home Manager

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

{
  targets.darwin.defaults = {
    "com.apple.Safari" = import ./defaults/com.apple.Safari.nix;
    "com.apple.finder" = import ./defaults/com.apple.finder.nix;
  };
}

Limitations

• This is a proof-of-concept tool focused on common use cases
• Some exotic macOS data types may need manual review
• Binary data is automatically skipped (by design)
• Complex custom objects may require additional handling
• System-level configurations may require root access to read completely