dex is a command-line utility for managing and executing Desktop Entry files (.desktop files) in Linux desktop environments. It implements the freedesktop.org Desktop Entry Specification to parse, validate, and act upon .desktop files. The tool provides functionality to execute applications from .desktop files, create new .desktop files, query properties of existing files, and manage autostart programs from standard autostart directories. The architecture centers around a well-designed DesktopEntry class that handles parsing and property access, with special attention to proper command-line string parsing in the Application._build_cmd method, which correctly handles quotes, escapes, and desktop-specific field codes. The tool has zero external dependencies, relying only on the Python standard library, and is actively maintained with recent commits and automated testing.