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.

• 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
• Flexible filtering with -filter flag (dates, state, uuids)

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

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

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

Convert defaults for a specific domain:

# Output to stdout
defaults2nix com.apple.Safari

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

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

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.

Usage: defaults2nix [flags] [domain]

A tool for converting macOS defaults into Nix templates.

Flags:
  -all       Process all defaults from `defaults read`
  -filter    Comma-separated list of items to filter out (dates,state,uuids)
  -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 -all -filter dates -o all-defaults.nix
  defaults2nix -all -filter state,uuids -o all-defaults.nix
  defaults2nix -split -o ./configs/
  sudo defaults2nix -all -o all-defaults.nix  # for system configs

The -filter flag accepts a comma-separated list of items to filter out from the output:

# Filter out date values
defaults2nix com.apple.Safari -filter dates -o safari.nix

# Filter out UI state and UUIDs
defaults2nix -all -filter state,uuids -o clean-defaults.nix

# Filter out all supported types
defaults2nix -all -filter dates,state,uuids -o minimal-defaults.nix

# Works with split mode too
defaults2nix -split -filter dates,state -o ./configs/

⚠️ Warning: The filtering mechanisms are based on heuristics and pattern matching, which means they may occasionally:

• Filter out legitimate configuration values that happen to look like timestamps, UUIDs, or UI state
• Miss some values that should be filtered if they don't match expected patterns
• Be overly aggressive with timestamp filtering based on key names

Always review the filtered output to ensure important settings haven't been inadvertently removed. These filters are intended as a convenience for creating cleaner configurations, not as a precise data classification system.

• dates: Omits timestamp values

  • String dates: 2025-06-07 12:01:44 +0000, 2025-06-07T12:01:44Z, 2025-06-07
  • Unix timestamps: Integer values in timestamp-related keys (e.g., CKStartupTime = 1753218075)
  • CFAbsoluteTime: Floating-point values in timestamp-related keys (e.g., lastConnected@Display:2 = 774728050.470133)
  • Detects timestamps based on key names containing: time, date, timestamp, created, modified, updated, etc.

• state: Omits UI state and window geometry

  • Window frame positions and sizes
  • Split view configurations
  • Toolbar customizations
  • Table view settings

• uuids: Omits UUID keys and values

  • Standard UUIDs: A8604994-4D31-471E-B7F1-D60AC97A287C
  • Hashed identifiers: _19a3bc4999bddb89e1a44f4b87bdc37c (underscore + 32 hex chars)
  • Keys containing UUID patterns
  • Helps create more reproducible configurations

The -split flag processes all available domains and creates individual .nix files for each:

# Creates separate files for each domain in the specified directory
defaults2nix -split -out ./configs/

# For complete coverage including system-level configs
sudo defaults2nix -split -out ./configs/

This will create individual .nix files for each domain found:

• com.apple.Safari.nix
• com.apple.finder.nix
• NSGlobalDomain.nix
• loginwindow.nix
• etc.

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"
    );
}

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"
  ];
}

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"

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

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

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

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

# 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;

# 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

# 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;
    };
  };
}

# 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;
  };
}

• 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