Q Although many of my documents have useful QuickLook previews available, some do not. How can I check whether QuickLook should support them?
A QuickLook relies on plugins which are supplied with different apps (and sometimes other software), and usually installed within the app bundle or its supporting files. If an app developer does not provide a suitable plugin, and the format is not supported elsewhere, no preview can be offered.
To view active QuickLook previewer plug-ins on your Mac, open Terminal, type
qlmanage -m plugins
and press the Return key. Each entry gives the URL of the plug-in (revealing the file type supported), its location on your hard disk, and its version number.
Updated from the original, which was first published in MacUser volume 30 issue 5, 2014.