Gallery of installed fonts

I want to view the fonts that are installed on my system. Specifically, I want the client-side (fontconfig) fonts, not the old-style X11 bitmap fonts on the server (for which xfontsel does an adequate job). I guess what I’m looking for would be called a font viewer or font gallery. I want to see a bit of sample text for each font, ideally configurable sample text.

How do I figure out which font file is chosen for a system generic font alias?

In Fedora 22, in KDE (plasma) System Settings -> Font -> Fonts, the setting for “General” is “Sans Serif 10”, for “Fixed width” is “Monospace 10”, for “small” is “Sans Serif 8”, for “Toolbar” is “Sans Serif 9”, for “Menu” is “Sans Serif 10”, and for “Window title” is “OxygenSans 10”.