After installing MarkUpsideDown, create a symlink so that markupsidedown is available in your PATH:
sudo ln -sf /Applications/MarkUpsideDown.app/Contents/MacOS/MarkUpsideDown /usr/local/bin/markupsidedownOpen a file:
markupsidedown README.mdOpen multiple files as tabs:
markupsidedown file1.md file2.md notes/todo.mdBoth absolute and relative paths are supported. If the app is already running, files are opened in the existing window.