When you double-click on a file in Windows, it will automatically open a default program that is configured to manage these types of files. It is common, though, want or need to use a different ...

While you can manually enter the commands to edit files in Terminal editors, in OS X you can set up a service to open files in a desired terminal editor from the Finder's contextual menu.

Right-click on the DAT file you want to open and select Open with from the drop-down menu, then choose the text editor. If the DAT file is a video, you can open it with its associated video app.