Open Start. Search for Command Prompt, right-click the top result, and select the Run as administrator option. Type the following command to browse to the folder with the files you want to compare ...

Navigating and Opening Files with Command Prompt in Windows Using the Command Prompt in Windows can be a powerful way to manage and open files, especially when you need to perform tasks quickly or ...

The "open" program is specific to OS X and lets you basically drag and drop a file with the -a command onto an application. This way it overrides the per-user OBJ open-with settings.