macdefault

A macOS command-line utility for switching default file associations by file extension.

Overview

macdefault changes the default app for any file extension using macOS LaunchServices and duti. It also includes preset switches for common office suites.

What it does:

• Pick a default app for any extension interactively (--ext=mp3).
• Switch office presets in one command (--microsoft, --wps, --apple).
• Show current defaults and installed bundle IDs for troubleshooting.

Preset extensions (suite mode):

• doc, docx, xls, xlsx, ppt, pptx, rtf, csv

Requirements

• macOS
• Python 3.10+
• duti (brew install duti)

Quick Start with uv

brew install duti
uv tool install macdefault
macdefault --help

Installation

pip

python -m pip install macdefault
macdefault --help

From source (development)

git clone https://github.com/ac1982/macdefault.git
cd macdefault
uv sync
uv run macdefault --help

Usage

Set any extension

Choose a default app for a specific extension:

macdefault --ext=mp3

Show candidates without making changes:

macdefault --ext=mp3 --show

Interactive selection:

• Up/Down arrows to move
• Enter to confirm
• 1-9 to quick select
• q to cancel

Switch office suites

Switch all preset extensions to Microsoft Office:

macdefault --microsoft
# or
macdefault --office

Switch to WPS Office:

macdefault --wps
# or
macdefault --kingsoft

Switch to Apple iWork:

macdefault --apple

Diagnostics

Print a summary of installed suites:

macdefault --print-bundle-ids

Full diagnostic output (bundle IDs + current defaults):

macdefault --doctor

Additional options

Dry run (preview changes without applying):

macdefault --microsoft --dry-run

Disable verification (skip checking if changes succeeded):

macdefault --wps --no-verify

Fail fast (stop on first error):

macdefault --apple --fail-fast

How It Works

1. Discovery: scans common application directories (/Applications, etc.)
2. UTI matching: uses macOS Uniform Type Identifiers to find apps that support each extension
3. LaunchServices: registers apps with lsregister when needed
4. duti: applies defaults via duti -s <bundle-id> <extension> all
5. Verification: checks that changes were applied correctly

Special handling

• WPS Office: uses a stable path (/Applications/wpsoffice.app) since LaunchServices name lookup can be unreliable
• Microsoft Word .doc: includes repair logic if the default does not stick

Troubleshooting

"duti not found"

• Install via: brew install duti

"Microsoft Office apps not fully resolvable"

• Ensure Word, Excel, and PowerPoint are installed in /Applications
• Try running macdefault --print-bundle-ids to see what is detected

Changes do not stick for .doc

• The script re-registers Word with LaunchServices and tries multiple UTI identifiers

App not appearing in --ext list

• The app must declare support for that file type in its Info.plist
• Workaround: Finder right-click file -> Open With -> Other -> Change All

Project Structure

macdefault/
├── macdefault.py       # Main script
├── pyproject.toml      # Project metadata and dependencies
├── README.md           # This file
├── .python-version     # Python version specification
└── .gitignore          # Git ignore rules

Development

Running tests

# Add tests in the future
uv run pytest

Code formatting

# Add formatters as dev dependencies if needed
uv add --dev ruff black
uv run black macdefault.py
uv run ruff check macdefault.py

Technical Details

• Uses mdls for fast metadata queries when available
• Falls back to parsing Info.plist directly
• Filters out overly-generic UTIs (public.data, public.item, public.content)
• Supports wide Unicode characters in table output via wcwidth
• Interactive mode supports q to cancel

License

MIT License - See LICENSE file for details.